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Articles from 1998 In October

Three ways to break data gridlock

1. Cable modems: That's entertainment

Cable modems allow high-speed Internet access via a cable TV network. A splitter lets users watch cable TV while still being

Cable modems take advantage of the cable TV network to connect a PC to the Internet. Today's fastest analog modems operate at 56 kbps bidirectionally; cable modems permit downstream data rates up to 27 Mbps and upstream rates of up to 786 kbps.

Like all modems, cable modems work by modulating and demodulating signals. Because most cable networks are not now bidirectional, some cable modems today use standard telephone lines to transmit upstream information.

Two-way cable modem system connects IP (Internet protocol) network via hybrid fiber coax to a home

Motorola's (Mansfield, MA) Cable Comm technology uses the CyberSURFRTM cable modem at the subscriber premises and the Cable Router at the headend. The system offers downstream rates up to 30 Mbps, of which 10 Mbps is available to an individual modem. The upstream data rate is 768 kbps. This downstream rate is faster than a T1 line commonly used in office buildings.

2. Dense wave-division multiplexing (DWDM): Exponentially increasing fiber capacity

DWDM turns a single fiber-optic cable into a "virtual" cable with dozens of strands. It's a lot cheaper than laying more cable across the country.

Wave-division multiplexing (WDM) lets multiple data channels at different wavelengths share a common optical fiber. Dense WDM increases fiber capacity by assigning signals to specific frequencies within a designated frequency band and then multiplexing the resulting signals out onto one fiber.

Wave-division multiplexing doubles the capacity of a fiber by making possible the simultaneous transmission of two optical signals at two discrete wavelengths. Dense WDM combines multiple optical signals so that they can be amplified as a group and transported over a single fiber to increase capacity. The signals can be different formats and running at different data rates.

GigaMuxTM from Osicom Technologies (Santa Monica, CA) is a 32-channel dense wavelength division multiplexer that transforms existing fiber-optic cable from a dedicated single-application medium into a conduit that can simultaneously transport multiple optical channels. The device supports multiple data formats including: SONET, ATM, G-Ethernet, fiber channel, and switched digital video. The technology increases a single fiber's bandwidth from 2.5 to 80 Gbps.

Future DWDM terminals will be able to carry up to 80 channels, or wavelengths, for a total bandwidth of 200 Gbps, or 40 wavelengths for a total of 400 Gbps.

3. Splitterless ADSL: Fast technology gets less complex, expensive

ADSL (asymmetric digital subscriber line) technology allows traditional voice and digital data to coexist on the same copper telephone line. The technique delivers high-bandwidth, multimedia applications such as streaming video, interactive gaming, and fast Internet access.

Splitterless ADSL uses modems with a high-pass filter to block interference from voice-range frequencies. A low-pass filter attached to telephones prevents data traffic from interfering

Splitterless ADSL eliminates the need for an external splitter to separate voice traffic from high-speed data traffic. Practically, it means service providers won't have to physically install the splitter outside a customer's home. This reduces cost and complexity of ADSL, which--without the splitter--can deliver up to 1.5 Mbps downstream and 512 kbps upstream.

Texas Instruments (Houston) this year announced a splitterless ADSL implementation that uses its 1,600-MIPS TMS320C6000 DSP technology, as does TI's full-rate ADSL implementation, which provides data transfer rates up to 8 Mbps. Thus, the chip supports both full-rate ADSL and reduced rate splitterless options G.lite and Universal ADSL.

The DSP-based chipset is a programmable solution, so manufacturers and consumers using TI's splitterless ADSL can upgrade via software to the G.Lite standard once it is fully defined and approved next year. Once that occurs, TI will use the 'C6000 core to build a custom programmable chipset that conforms to the standard.

Rugged design takes test electronics anywhere

Time may wait for no one, and neither do the needs of manufacturing plants or remote field sites when a piece of equipment goes down. But troubleshooting equipment must not only stand up to the rigors of harsh environments. It must also allow operators to get to the heart of a problem without worrying about the integrity of their diagnostic tools.

So just how do designers build ruggedness, and thus peace of mind, into their products?

When anything electrical or containing electronics gets squirrelly, whether it's in the design test lab, the plant, or even at home (an engineer's that is), most people bring out the multimeter first. Modern versions of the digital multimeter (DMM) range from simple current/voltage/resistance units to devices that can display waveforms on large LCD display screens.

Frequently used in confined spaces, a DMM can be easily dropped on or banged against unfriendly surfaces. Displays, switches, and connections have to be able to take such poundings, and the meter itself may be subjected to inadvertent electrical overloads.

No fluke. Chuck Newcombe, product planner for DMMs for Fluke Corp. (Everett, WA)--long known for the durability of its products--says there are several keys to designing robustness into test equipment.

An understanding of the user's environment, including the physical conditions, such as dust and water, and the electrical loads and electromagnetic interference, is critical, he emphasizes. "The conditions a design-test engineer on a workbench encounters are quite different than those an electrician on a catwalk in a steel mill (heat), pulp mill (humidity), or cement plant (dust) runs into," he notes. "For some time, we have put designers into the customers' shoes, getting them into the field, whether it's a steel mill or a repair truck."

When it comes to high electrical energy concerns, not only ruggedness but also safety come into play (see DN, 4/20/98, p. 96). Ideally, the test instrument should be able to continue to take measurements, or at minimum survive and be reset, after an overloading. Sturdy switches and proper fusing help ensure electrical safety and avoid failures. In any case, Newcombe explains, "You don't want the instrument contributing to a fault, and if it should fail, you want it to fail safe."

The European IP standards and tests are part of the world-wide environmental specifications being adopted, according to Newcombe, for device seal quality (dust and moisture integrity, per IEC 529). These standards specify, for instance, the contaminants that can enter a device's case and at what levels. Corrosion and oxidation concerns have lead to use of gold-plated contacts to prevent open circuits.

After designers account for the environment, they need to consider accidental dropping and other abuses. The IEC standard for hand-held devices specifies that they must survive a 1m drop onto a 50-mm layer of oak on concrete. Fluke sees the standard as a minimum and guarantees that some products can be dropped twice that distance and still maintain calibration and usefulness.

To improve the robustness of its products, the company does six different axes orientations at each drop test distance. Newcombe adds that the products are dropped from progressively higher heights onto a concrete surface until they fail, which helps to improve future designs.

Analysis software provides insight into the packaging of test instruments so they withstand high loads. Commercial design packages used by Fluke for geometry configuration and finite element analysis include Pro/ENGINEER® from Parametric Technology Corp. (Waltham, MA) and ANSYS/Pro from ANSYS Inc. (Canonsburg, PA). With the software, designers can try out different case shapes and explore the resultant stress development under loading.

Yellow jacket. Years ago, a removable rubber holster protected Fluke's multimeters. That has been supplanted by a protective jacket or boot, in familiar yellow. Integral to the case, this bonded layer is stronger than the rubber holster, according to Newcombe, and more effective in preventing impact damage. The design also allows for better stress distribution and eliminates velocity differences between the boot and the hard case underneath.

Protecting the instrument display, such as a DMM LCD, under shock is a prime concern. Depending on the specific device, "You may not want to 'float' the display, and maybe 'tying it down' would be better," notes Newcombe. Designers make radius and clearance changes to the case in order to produce the lowest g forces on the glass. Elastomeric strips connect the LCD glass to the circuit boards, avoiding contact breakage. Analysis results are proven out by dropping ball-bearings onto the LCDs.

Tektronix (Beaverton, OR) was also concerned with screen ruggedness in designing its new TX-DMM. Engineers stabilized the LCD by supporting it across the entire back surface using both the chassis and light diffuser. By effectively locking the display into place, the design minimizes bending and twisting motions. A plastic bezel surrounding the front of the display adds protection.

Fluke's Newcombe says the low mass of these small, hand-held devices means less impact energy, resulting in lower stress levels. In fact, the spring pressure on internal connector pins produces friction much greater than any inertial forces tending to pull them apart.

Larger devices, on the other hand, can contain more massive independent internal components, such as batteries. Likewise, big, desktop instruments require internal components, such as transformers, that under some loads (typically in transit) may even bend the chassis. To prevent damage, engineers design transport packaging to directly support these bulk masses. For example, removable bolts attached to the instrument case, housed in a padded shipping box, prevent inertial loads from entering the chassis.

Recessed switch handles that prevent direct shock loading of the switch also contribute to ruggedness, adds Newcombe. The use of surface mount components eliminate the problem of g loads bending or destroying fragile leads. Probe connectors now have integral rubberized shrouds to allow leads to flex without breaking.

Locking LEDs. When coming up with the design for their DMM, Tektronix engineers were also concerned about the LEDs for display lighting. The diffuser panel conforms to fit around each LED, which together provide even backlighting. Designers were worried that if the meter was dropped repeatedly, these light sources would begin to fatigue, ultimately shearing right off their mounting board. The amount of light available would then start to decrease. The solution: allow the diffuser and board to move together, by beefing up the pins holding them together. Eliminating the motion reduced the stress between them.

The Tektronix DMM window is a single part molded from Lexan® polycarbonate film from GE Plastics (Pittsfield, MA). Featuring greater strength and stiffness than the three separate components it replaced, it functions not only as the window for the display but as a covering for the infrared port.

Finally, the blue rubber boot encasing the DMM has a built-in, swing-out stand. Tektronix views even this as an enhancement, as not only can the instrument be set up on a bench, it also can be hung from a shelf or hook. Either setup minimizes the actual chance of dropping the instrument.

In the end, it's a combination of all three--design software, packaging experience, and materials--that put ruggedized testing into go-anywhere packages.


Some standards to meet

Safety tests to specs:
IEC 1010-1, ANSI/ISA S82.01, CSA 22.2
No. 1010.1

EMI compatibility:
RF Emissions - EN 50081-1
RF Susceptibility - EN 50082-1

Environmental (dust and moisture):
IEC 529

Product news

Electro Forms

Baffled electroforms and other custom-electroformed components requiring close inside tolerances, precision internal finishes, and thin walls can be made to print. Diameters as small as 0.035 inch and as large as 6 inches can be produced in either nickel, copper, gold, or silver. Lengths up to 6 inches can be readily produced, as can closed-end tubes. Flexible components can also be manufactured by combining a formed unity with a flexible bellows section. Nickel components can be furnished in weldable or solder grades to enable assembly.
Servometer Corp.
501 Little Falls Rd.
Cedar Grove, NJ 07009
FAX (973) 785-0756.


The SEI Series one-piece connector on 1-mm pitch features an ultra-low profile of 1.65 mm and low system cost achieved by processing one connector. Phosphor bronze contacts provide high normal forces with a large constant deflection of 0.020 inch when the boards are mated together. These interfaces are surface-mount soldered to one board and fastened to the mating board.
Samtec Inc.
Box 1147, New Albany
IN 47151
FAX (812) 948-5047.

LED assemblies

The 5681G Series of two-high T1-sized multiposition LED assemblies are gangable from two to eight positions and provide versatility as well as performance specifications for LAN, telecommunications, and electronic equipment applications. The assemblies are available in standard red, green, and yellow. Low-current 5 and 12V and bi-color options are available. The assembly features press-in pins to hold the array to the board during soldering.
Chicago Miniature Lamp Inc.
147 Central Ave.
Hackensack, NJ 07601
FAX (201) 489-6911.

Gear boxes

The "Z" Series spiral-bevel gear boxes have been streamlined to increase the number of common parts. Two- and three-shaft, forward, neutral, and reverse models with solid through-shaft or hollow-bore designs, and cubic housings machined on all six faces for integration into designs combine to offer 30 possible mounting configurations.
Andantex U.S.A. Inc.
1705 Valley Rd.
Wanamassa, NJ 07712
FAX (732) 493-2949.

Touch screens

Touch screens are transparent glass substrates coated with polyester film and transparent conductive coatings. The screens are used in manufacturing environments, point-of-sale terminals, and public information systems to acquire information and input data. Touch screens are available in capacitive and resistant matrix and resistive analog form.
The Bergquist Co.
1600 Orrin Rd.
Prescott, WI 54021
FAX (715) 262-3738.


Precision cold-drawn seamless hard aluminum alloy tubing is available in a variety of special shapes, including ovals, rectangles, squares, and others. Alloys available are 2024, 5052, 6069, and 7075, in a variety of tempers to meet formability and strength requirements. Round tubing is also available in 6061 alloy.
Plymouth Tube Co.
6573 W. Willis Rd.
Chandler, AZ 85227
FAX (520) 796-0596

Desktop workstation

The COMPstation® U236064-bit desktop workstation uses dual 360-MHz UltraSPARC-II processors to provide a SBus-based computing solution. The system offers up to 2 Gbytes of memory and features SMP capabilities. SMP, available as a standard feature, distributes the operating system and applications across multiple processors for faster execution.
Tatung Science & Technology Inc.
1840 McCarthy Blvd.
Milipitas, CA 95035
FAX (408) 383-0886.

Color displays

Model ECT-VGA 10.4-inch diagonal passive color operator interface and ETT-VGA active-matrix TFT color display helps improve data entry while reducing operator error by allowing the user to display a visual picture of the entire process on the 10.4-inch color screen. The display features 11 front-panel membrane push buttons. Encased in a rugged housing, both VGA models are suited for a harsh industrial environment, and feature CE, UL, CSA, and NEMA 4/12 ratings. Model ECT-VGA and ETT-VGA feature full 16-color graphics capability with three ports for controller, printer, and high-speed FIELD BUS networks.
3460 Fairlane Farms Rd., Suite 12
Wellington, FL 33414
FAX (201) 842-0039.


The VP150 LCD monitor features 250 units of luminance and an extended backlight life rated to remain operational for up to 50,000 hours under normal usage standards. With SmartPanel resolution management technology, this flat panel display produces crisp, vivid, sharp screen images at all resolutions up to 1,024 3 768. The display also supports a true 16.2 million colors. The VP150 also features a 15-inch viewable screen and wide 14-degree horizontal viewing angle.
Viewsonic Corp.
Walnut, CA
FAX (909) 468-3756.

Visual modeling software

Software through Pictures version 2.6 features full support for Validator/Req. 1.2, a testing tool. Software through Pictures is a component-based, visual-modeling toolset that, combined with Validator/Req. 1.2, enables requirements-driven validation and testing. The suite provides code generation and reverse engineering for many popular languages, including Java, C/C++ Ada, Forte, and IDL, and offers full integration with the Dynamic Object Oriented Requirements System requirements-traceability tool.
595 Market St., 10th Floor
San Francisco, CA 94105
FAX (415) 543-0145.

Effector set

Director Xtra Effector Set Vol. II for AlphaMania gives macromedia director developers interactive special effects like blur, ripple, drop shadow, bevel, and roil. The Effector Sets work with AlphaMania, an Xtra that gets rid of the "jaggies" and allows developers to position their graphics on top of any background without the fringe that appears when moving bitmapped castmembers in Director.
Media Lab Inc.
31 S. 80th St.
Boulder, CO 80303.


ACIS® 4.1 features modern, open C++ architecture that enables developers to incorporate advanced 3D modeling functionality into their applications rapidly. An Interactive Hidden Line (IHL) function quickly generates hidden line information based on the faceted representation of the model. IHL generates views of large, complex models. A definitive error-handling feature provides more detailed information to developers, enabling them to provide more visual information to users about failures.
Spatial Technology Inc.
2425 55th St.
Boulder, CO 80301
FAX (303) 442-5921.

Single-board computer

The ILH-386V half-sized single-board computer features VGA/flat panel display support, as well as the optional PROMDISK-Chip Disk emulator. The VGA display port is compatible with a number of flat-panel displays. Along with the standard I/O features, the ILH-386V includes a 1K-bit E2Key memory for storing user data such as critical system parameters and terminal addresses. The ILH-386V is equipped with an infrared data port for wireless communications, a PC/104 expansion port, and four serial ports including an RS-422/485-compatible port.
2598g Fortune Way
Vista, CA 92083
FAX (760) 598-2450


Tol-O-MotionTM software is for the sizing and selection of electric motion systems. Used with its expanded Axidyne® electric linear motion product line, Tol-O-Motion software provides complete electric motion solutions, eliminating the time and hassle of mixing, matching, and integrating components.
Tol-O-Matic Inc.
3800 Country Rd. 116
Hamel, MN 55340.

2D software program

AutoDetailer 2D software program works with AutoCAD and automatically produces detail drawings from assembly Wblocks or part drawings. The software reads the Dxf file of part drawings to determine which views are available and their relationships, and knows what is milled, drilled, tapped, or turned. From this data, the program determines the necessary dimensions, correct paper size and scale, the hole, and corner call-outs. AutoDetailer then writes a script file that AutoCAD understands to produce the detail drawing.
Wikoff Concepts
5221 Creek Rd.
Cincinnati, OH 45242

Prototype controller

RCS+ advanced machine controller combines CNC, soft logic, and general motion control in a single control architecture. It uses off-the-shelf components and the Windows NT operating system, with no proprietary motion boards. Standard Windows NT interfaces provide integration of business, engineering, and plant floor information systems. The controller combines CAD/CAM with a shop floor programming system on Controller HMI.
Advanced Technology & Research Corp.
RCS Automation Div., 15210 Dino Dr.
Burtonsville, MD 20866
FAX (301) 989-8000.

Optical design software

CODE V® Version 8.30 optical design software is for Windows 95/NT and Sun Workstation platforms. Code V 8.30 features optimization, thin-film coatings, user-defined macros, illumination system analysis and output plotting, as well as better integration into the Windows environment. The Global Synthesis® optimization algorithm has been improved for zoom lenses, and the number of variables allowed during optimization has been nearly doubled to facilitate the design of complex systems.
Optical Research Associates
3280 E. Foothill Blvd., Suite 300
Pasadena, CA 91107
FAX (626) 795-0184.

Data acquisition system

The AD128 ReadyTecTM pocket-sized data acquisition system is a complete stand-alone system, which includes all of the features of the Model AD128 and the full-featured configuration and analysis software, but with reduced data storage capacity. The software runs on Windows 95, NT, or 3.1, and ensures that data can be recorded and quickly downloaded into a built-in spreadsheet. The software enables users to configure the logging unit and visualize and analyze data just recorded.
Valitec Inc.
5115 Crispy Dr.
Dayton, OH 45440
FAX (937) 291-9148


The 68HC16Z3 16-bit microcontroller features a RTECTM operating system kernel on-chip and is for real-time control applications. A streamlined version of the RTEK kernel fits into the 68HC16Z3's 8 Kbytes of ROM, and provides 94 services to manage program tasks and resources such as the CPU, memory, and time. The kernel also enables real-time data manipulation and provides a common application programming interface (API) for all related tasks. Included with the RTEK developers kit is RTEKgenTM, a graphical system generation program that simplifies system configuration.
Box 13026
Austin, Texas, 7871

Memory products

High-density memory products are for Digital Personal Workstation Models 433, 500, and 600. The products are available in 64, 128, 256, and 512 Mbyte sizes and are fully tested to be compatible with both the au-series and the a-series.
Camintonn Corp.
22 Morgan, Irvine
CA 92618
FAX (949) 830-4726.


F3348 and F4108 Series ultra-miniature surface-mount oscillators offer frequency stabilities of ±20 PPM inclusive of tolerance and temperature range. Series F3348 oscillators measure 5 3 7.5 mm, and offer a frequency range between 1.544 to 50 MHz. Series F4108 oscillators are available in 3.3V, and offer a frequency range of 1.544 to 50 MHz. The tight stability of these oscillators target them for use in wireless communications and similar demanding applications requiring high precision and performance.
Fox Electronics
5570 Enterprise Pkwy.
Fort Myers, FL 33905

Membrane monitor and manager

The im3 intelligent membrane monitor and manager increases membrane life and system efficiency and reduces labor. The im3 optimizes the process and clean cycle first by tracking the clean cycle permeate flow. As the filter is cleaned, the permeate flow increases. When the flow does not increase for a predetermined period of time, this indicates the filter's peak flow and that it has been cleaned as well as it can be. The value of the peak flow is recorded and displayed on the front panel.
Edjean Technical Services Inc.
22036 Fairgrounds Rd.
Wellington, OH 44090
FAX (440) 647-2400

Mass-flow measurement system

The Promass 60 with HART® mass-flow measurement system offers the flexibility to program any full-scale value for the current and/or frequency output. The system can be set up using DIP switches or the HART hand-held. An additional setup option employs the Commuwin II configuration software. Promass 60 with HART offers free programming of low-flow cutoff, noise suppression, and empty pipe detection.
2350 Endress Pl.
Greenwood, IN 46143
FAX (317) 535-8498


Model MFE timer is 22.5 mm wide and performs six most widely used industrial timing functions, including on delay, off delay, single pulse on on, flasher starting with on, flasher starting with off, and non-retriggerable one shot for pulse-forming applications. UL-approved, CSA-certified, and CE-marked, the timer snaps onto a DIN rail or may be panel-mounted. The timer offers eight timing ranges from 0.05 sec to 100 hours.
Entrelec Inc.
1950 Hurd Dr.
Irving, TX 75038
FAX (800) 862-5066.

Heat-transfer fluid

Oxidation-resistant (ORTM) heat-transfer fluid features unusual oxidation resistance and high flash and fire points. The fluid precisely and uniformly controls process temperatures in closed-loop, liquid-phase heat transfer systems to 600F. The fluid is non-fouling, and will not coat the system's heated surfaces with hard, baked-on carbon deposits when severely overheated.
Paratherm Corp.
1050 Colwell Rd.
Conshohocken, PA 19428

Chart recorder

The WekslerTM ECR153 chart recorder is microprocessor-based to record pressure or temperature in one- or two-channel configurations. Versatile input modules provide the ability to record 4/20 mA, 0/1, 0/5, and 1/5V dc output devices as well as standard RTD and thermocouples. Custom colors and logos are available for applications. The chart recorder's features can be accessed from the front panel. A four-button keypad simplifies paper change, setpoint programming, and zero adjustment.
Instrument Div.
250 E. Main St.
Stratford, CT 06497.


The Pocket-Probe® sealed pyrometer allows the user to measure temperatures from -280 to 2,000F/C equivalent under any adverse condition. This pyrometer is impervious to water, gas, oil, dust, cleaning solutions, and hot splashes up to 300F. The Pocket-Probe handles high impact and pressure without affecting its 1-degree accuracy or inherent sealed characteristics.
Electronic Development Labs Inc.
244 Oakland Dr.
Danville, VA 24540
FAX (804) 799-0847.


The LC584AXL high-performance color oscilloscope features technology for capturing multiple waveforms in an Analog PersistenceTM display mode and the ability to make precision calculations using the data in the persistence map. The oscilloscope extends the ability of high-performance DSOs to accurately capture complex signals and make precise measurements concerning their characteristics. To do so, it offers 4 Mbytes of data-acquisition memory per channel and the ability to cascade the memory to offer 16 Mbytes of acquisition memory when using a single input.
700 Chestnut Ridge Rd.
Chestnut Ridge, NY 10977

Remote monitoring chassis

The 7724 Series rack-mounted remote monitoring chassis is for factory automation, building security, and other demanding, high-reliability applications. The chassis monitors all functional system aspects, and is capable of performing its monitoring and notification functions even in the event of a total power failure, as it is functionally self-contained and internally battery-backed.
Industrial Computer Source
Box 910557
San Diego, CA 92191.

Test gauge

Model AK digital-pressure test gauge attains 0.05% full-scale accuracy for pressure ranges from 15 to 10,000 psi. This enhanced-resolution, 41/2-digit display eliminates parallax and interpolation errors and makes this gauge a transfer standard for calibrating pressure-measuring equipment, including other gauges and transducers. The series features high/low capture and an update speed field-adjustable from three to 10 times/sec.
DCT Instruments/Sensotec Inc.
2080 Arlingate Lane
Columbus, OH 43228
FAX (614) 850-1144.

Color camera

The Memrecam Ci/RX-2 color camera features a detachable, compact camera head and is a ruggedized, high-speed image capture system that can fit in small places. The camera can withstand high acceleration to as high as 150 Gs. The system, including processor and removable camera head, weighs 11 lb and is self-contained with no moving parts. The Memrecam Ci/RX-2 captures 500 color frames/sec for up to 4.3 sec of record time at a full resolution of 508 3 480 pixels with maximum memory.
Eastman Kodak Co.
Motion Analysis Systems Div.
11633 Sorrento Valley Rd.
San Diego, CA 92121.

Pump-down control

The 4052 pump-down control features five setpoints and provides total control for duplex pumping systems up to a depth of 34.6 ft. Features include adjustable universal On Delay to prevent outputs from closing due to input fluctuations caused by turbulent conditions, heavy-duty output contacts for pump control and alarm activation, high and low alarm outputs, and an SPDT power loss relay. The 4052 also features duplex pump alternation, dual run-time meters, and hand-off-auto operation for both pumps.
Time Mark Corp.
11440 E. Pine St.
Tulsa, OK 74116
FAX (918) 437-7584.

Hourmeter-counter module

Series T1100 LCD hourmeter-counter module features a six-digit, seven-segment LCD display. This small-size product has high shock and vibration specifications. The hourmeter model displays hourglass and decimal points. The accumulated hours are stored on powerless, non-volatile data back up using CMOS EEPROM technology where small space and reliable instruments are required with memory that does not rely on a battery.
5617 Northwest Hwy.
Chicago, IL 60646
FAX (773) 775-5968.


Model 612-TX tri-axial accelerometer weighs 8 gm with a volume of 0.082 inches3. The sensor is equipped with a micro-miniature detachable cable assembly. Complete mechanical and electrical isolation of the transducers minimizes ground loop problems and spurious signals from cable whip.
Columbia Research Laboratories Inc.
1925 Mac Dade Blvd.
Woodlyn, PA 19094
FAX (610) 872-3882.

Test stand

Model BG-1 micro-dilution test stand is an automated sampler for diesel exhaust particulates and improves measurement accuracy, repeatability, test-lab throughput, and data management capabilities. Flow monitoring and proprietary calibration functions are available. All dilution air conditioning and cooling is accomplished in a compact, portable package. The unit is a "full flow fractional sampler," where all flow extracted from the exhaust stack is diluted and filtered.
Sierra Instruments Inc.
5 Harris Ct., Building L
Monterey, CA 93940
FAX (408) 373-4402.


The Power Check pull-force gauge measures the drawbar pull force of steep taper and HSK machine tool spindles. The gauge can be used on other tool standards by changing the ad

PDM gets PDQ

Despite PDM's relative slow start and some bad press along the way, industry analysts expect sales of Product Data Management software to keep chugging along right into the next century.

The reason? Efforts by vendors to improve the ease-of-use and extend the flexibility and interoperability of their PDM offerings appear to be paying off. The average implementation time to full deployment, for example, ranges from a mere 120 days to 18 months. That's down significantly from just a few years ago, according to PDM software vendors surveyed for this article.

Similarly, as PDM gains more of a foothold in industry, vendors now have experience in interfacing their software with more CAD applications in the field and other, varying sources of data (see chart at end of article). Moreover, many companies now even offer a full-functioning, open Application Programming Interface (API), so that users can more easily integrate to any software package they may desire.

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Ease-of-use, greater experience, and rapid implementation times help spur sales of PDM software. The basic PDM market more than doubles when services are factored in.

Relatively new to the field are Windows-based offerings by companies like Agile Software and SmartSolutions. Not designed to compete with the full-blown, enterprise-wide PDM solutions, these economical, out-of-the-box solutions boast quick implementation times. Designed to resemble the Windows-based environment most engineers work within, the templates available with these packages are usable as is, or they can be customized by the user.

The bottom line for companies contemplating PDM today? As the following success stories illustrate, they can more quickly achieve the benefits of PDM--including shortened product development cycles, fewer engineering changes for released parts, less paperwork, and fewer part counts to name a few. And that time savings--as every good engineer and accountant knows--is as good as money in the bank.

Product data management

User: Raytheon Aircraft Co.

Location: Wichita, KS

Product line: Aircraft parts and assemblies


Operating platform: UNIX and Windows95

Number of seats installed:>1,200

Types of data sources tied in and specific applications:
Rosetta Preview for viewing; CATIA CAD information; host-based MRP system; bills of materials

Implementation time: 12 months

Goals and requirements: Reduce product development cycle by 40%

Specific benefits:
Raytheon has been able to reduce the product development overall cycle because parts and assemblies fit more accurately the first time. They have also experienced a 10:1 reduction in engineering changes for released parts, which also is a factor in reducing the overall development cycle.

Reasons for selecting ENOVIATM:
Functionality; Strength and breadth of services capabilities; Domain expertise in product development; Ability to implement on an enterprise scale.

User: Motor Coach Industries

Location: Winnipeg, Manitoba, Canada

Product line: Motorcoaches

PDM package: IMAN from Unigraphics Solutions

Operating platform: HP UNIX

Number of seats installed: 25

Types of data sources tied in and specific applications: Production, sales engineering, field services

Implementation time: 48 months, including technology selection and complete implementation

Goals and requirements:
To produce a state-of-the-art motorcoach to recover lost market share through leading edge use of people, process, and technology and to cut product development time in half

Specific benefits:
Reduced build hours by 47%; Slashed assembly stations from 68 to 16; Eliminated seven levels in the bill of materials; Trimmed suppliers from 53 to 48; Increased generic part count from less than 70 to more than 90%; Reduced parts count from 37,000 to 17,000; Reduced product cycle time from 60 to 34 months

Reasons for selecting IMAN:
MCI selected Unigraphics Solutions both for its technology strengths and implementation track record and its capability to deliver Virtual Product Development, leading-edge technology, and a quick response time.

User: Danfoss Drives

Location: Graasten, Denmark

Product line: Variable frequency converters to control motors, fans, and pumps

PDM package: Metaphase Enterprise PDM, will also use e!Vista, Metaphase's Java-based client interface in the near future

Types of data sources tied in and specific applications:
SAP (for managing ERP); CAD/CAM/CAE drawings; EPROM (erasable programmable read-only memory) files, labeling systems, manuals, and documentation

Goals and requirements:
To integrate up-to-date product data and product structure information into the ERP system; to reduce cycle and delivery time from weeks to two days. (Both goals were met.)

Specific benefits:
Two-day product configuration, manufacture, and delivery; Ability to access a Java-based Web catalog, configure products on-line, and submit the order directly into Danfoss's Enterprise Product Data (EPDM) system

Reasons for selecting Metaphase Enterprise 3.0:
Danfoss needed bottom-up control of product structure information such as CAD/CAM/CAE drawings; EPROM software files, manuals, and documentation; labeling systems; and other areas. This control had to integrate with the parts, planning, and logistical views provided by SAP in one seamless system. The answer was an advanced EPDM solution with a SAP interface. Metaphase was the only EPDM supplier that "saw the project from the perspective of our business processes."

User: Gencorp/Aerojet

Location: Sacramento, CA

Product line: Propulsion, electronics, and weapon systems

PDM package: Sherpa/IPD

Operating platform: UNIX

Number of seats installed: 200 plus at two sites

Implementation time: 3-6 months of conversion and new data load for specific program

Goals and requirements:
Already a Sherpa PDM user, Aerojet wanted to remove all dependency on customization and take advantage of technology improvements and increase user acceptance.

Specific benefits: Deliver critical data speedily; Gained the ability to work with varied platforms; Better teamwork

Reasons for selecting Sherpa/IPD:
Aerojet emphasizes that the ability to purchase an "out-of-the-box" solution from Sherpa was very attractive. "We're not a software company, we're an aerospace products company," a representative said. Aerojet looked at a variety of vendor PDM solutions, "many of the other offerings were simply PDM toolkits that would have required us to configure the software to our particular needs--a major undertaking," he stated. "With Sherpa's solution we were able to get to work on this new project almost immediately. And that means we'll be able to significantly reduce our time-to-market." "We also found that many solutions were operated like managed CAD systems. While these will probably be developed into more robust systems, we felt that Sherpa was the best, truly enterprise-level solution available today."

User: Harmon Industries

Location: Grain Valley, MO

Product line: Mechanical and electrical products for railroad, freight, and transit industries

PDM package: WGT's CMS 6.5 and CMS Workflow

Operating platform: SGI server with PC clients

Number of seats installed: 300

Types of data sources tied in and specific apps:
100k files from 15 different types of files, including AutoCAD, Word, SolidWorks, PAD, Tango, and Myriad

Implementation time: Varied, implemented in three phases, based on business requirements and site locations

Goals and requirements:
Improve document distribution, speed-up access to engineering drawings for manufacturing, and eliminate microfiche

Specific benefits:
Drawings instantly accessible at all 13 company locations, and greater flexibility at manufacturing locations

Reasons for selecting CMS 6.5 and CMS Workflow:
Out-of-box features and functionality that best met requirements.

Servo fluid injection streamlines cardiac catherterization

To effectively treat coronary disease, physicians need to see how blood flows through the arteries and heart. To accomplish this, an intervential cardiologist injects radiographic material (contrast) into the patient, then views images of the coronary anatomy on overhead monitors. Acist Medical Systems (Eden Prairie, MN) claims to have developed the first angiographic-fluid-delivery system to combine programmable computer and motion-control technology with physician-interactive control for precise fluid delivery.

While the last decade has seen many breakthroughs in the devices used to treat coronary artery disease, angiographic-fluid-delivery systems have lagged behind. Most intervential cardiologists today use a confusing array of stopcocks, a maze of tubing, and an awkward hand syringe to inject contrast. Motorized injectors emerged several years ago for use in ventriculargrams that demand higher contrast volumes and rates. But they don't let the physician control and vary the flow rate during these injections.

With more than 2 million cardiac angiograms performed in the U.S. every year (Source: The Cowen Group), the opportunity to find a better method presented itself to visionary Robert Wilson. A noted University of Minnesota cardiologist, Dr. Wilson envisioned this new system would overcome the limitations of current angiography. "My colleagues and I joked about how we would like to perform angiography as simply as we pump gas in our cars--just squeeze a hand controller; the more you squeeze, the more you get."

Setting out to use as much off-the-shelf computer technology to semi-automate the process, Wilson teamed up medical and technical experts and founded Acist Medical Systems with the goal of providing the cardiologist with total control over every element of the procedure. "Competitive contrast systems are simply an on/off switch that delivers the entire amount of contrast programmed, with no variable control over the injection whatsoever," says Acist's Vice President of Marketing Mark Gillick.

"Additionally, manual systems have complicated setup requirements that take longer than our method. Our design simplifies the physician's work using an interactive, power-assisted control handpiece. The physician controls all aspects of the procedure with the AngioTouchTM controller while viewing injection data on the system's control monitor. The system's preset parameters help facilitate reproducible injection of coronary arteries. And allow the physician to choose more or less aggressive parameters with the touch of a finger."

The Acist system injects either contrast or saline fluids at the discretion of the physician during the cardiac procedure. It automatically aspirates and purges. "Because the injection process is more precise, shorter imaging times are possible, which means less radiation exposure for the patient and physician. And because it is a simpler system to set up and operate, fewer personnel may be required. It also conserves contrast media, and most important, new built-in safeguards maximize patient safety," says Gillick.

Sensors for safety. The automatic syringe is equipped with sensors to monitor the amount of available contrast, and the entire refilling process--including automatic purging of air--to ensure a continuous, uninterrupted supply of contrast media. The system automatically detects air as contrast is dispensed. Other safety features include a backlit automatic syringe and high-pressure tubing for enhanced visibility in the low light of the cath lab, along with a hand controller lockout to prevent unintentional actuation of the hand controller trigger.

Audible indicators alert the user of button depressions, system messages, and touch screen commands. The ACIST Injection System also provides the ability to automatically switch between high- and low-pressure ports so that the patient's blood pressure is monitored any time fluid is not being dispensed.

"Aside from a custom rod-type actuator from Tol-O-Matic (Hamel, MN), we use mostly off-the-shelf components," explains Acist's Vice President of New Product Development Doug Duchon. Leveraging technologies already proven in the field cut development time. "We designed custom electronics, consisting primarily of a dual-processor logic board and an analog power board, to support the motion-control hardware." Advanced Motion Controls supplies the AMC BE25A20 servo amplifier that runs in encoder-velocity-feedback mode. And a 2,000-line, incremental, digital, quadrature encoder system from U.S. Digital supplies feedback.

After receiving U.S. Food and Drug Administration clearance to market in December 1997, it was introduced at the March 1998 American College of Cardiology conference in Atlanta. And most recently, at the Tenth Annual Symposium on Transcatheter Cardiovascular Therapeutics, an estimated ten thousand physicians eagerly observed live-case demonstrations via satellite from hospitals in Washington D.C. and New York.

Injection system overview. The ACIST Injection System increases the efficiency and control of the cardiac catheterization procedure. First to combine fully programmable computer technology with physician-interactive control of fluid delivery into one complete system, it provides precise control of contrast flow into the coronary arteries while replacing all of the stopcocks and maze of tubing with a single line and the patented AngioTouch Hand Controller.

AngioTouch Hand Controller.The hand controller replaces the manual syringe, and is the only system to offer singlehanded, variable flow-rate control of all contrast and saline injections. No compromise in visualization under fluoroscopy is seen when injecting around PTCA balloons or intracoronary stents, allowing the use of smaller catheters for diagnostic (4 French) or interventional (6 French) procedures.

Touch screen monitor.Designed to provide precise injection and procedure information, the touch screen monitor provides a continuously updated display of total contrast delivered, the actuals of the last injection, and automatically refills the contrast syringe when needed. Moreover, it offers default parameters for the left coronary artery, the right coronary artery, or the left ventricle/aorta, based upon physician preference and patient weight.

Automated manifold. The system's automated manifold eliminates the need for a completely separate system for injecting coronary arteries or the left ventricle. Aspiration of contrast injection and saline flushing is controlled automatically and the system deposits waste material in a disposable bag. The system automatically switches the pressure transducer off/on, both before and after each injection, to support patient safety and physician control over the injections.

The pressure waveform signal instantly reappears once the injection is completed. This gives the physician total control of the procedure, and provides immediate access to the patient's vital signs without having to look down at the table to manipulate manifolds, stopcocks, etc.

"The physicians who have used the ACIST Injection System have been extremely impressed with the control they have over the entire angiographic procedure," explains Acist Vice President Mark Gillick. "Rather than looking down at the table to manipulate manifolds and stopcocks, physicians can now focus their full attention on the diagnosis and treatment, allowing them to deliver contrast at the touch of a button and accurately place a balloon or stent without ever taking their eyes off the monitor."

"ACIST moves beyond the limitations of both manual and motorized devices to set new standards for catheterization performance," says Gillick. The system's modular design easily fits various cath-lab configurations. It simplifies delivery of contrast media into the patient's arteries, while increasing the procedure's efficiency, productivity, and patient management. ACIST offers single-hand control, touch screen convenience, complete procedure monitoring, and continuous optimal/variable fluid-injection control.

That was then, this is now...

Manual and Power Injections

Continuous turning of stopcocks for injecting, refilling, or monitoring pressures

  • Mechanical injection system also used (with additional disposables)

  • Inability to vary the rate of injection with power injectors

  • Wide variety of disposables (multiple stopcocks, tubing, and syringes)

  • Contrast waste

  • Cumbersome maze of tubing

  • Injections limited by the physician's hand strength

ACIST Injection System

Total physician control over the entire procedure

  • Precise control of contrast media delivery with the AngioTouch hand controller

  • One standardized system to inject contrast, saline, aspirate, and purge

  • Touch screen monitor for precise injection and procedure information

  • Preset or customized parameters for reproducible injection of coronaries

  • Simplifies procedure allowing greater focus on the patient and diagnosis

  • Facilitates use of smaller catheters without compromising performance or image quality

Rod-type actuator frees physician's hands

Key to Acist's fluid-injection control is Tol-O-Matic's electrically powered, screw-drive actuator. "While the actuator's design is straightforward," explains Acist's VP of R&D Doug Duchon, "Tol-O-Matic's ability to prototype rapidly and give us exactly what we needed made the choice easy. Moreover, because we are a small company, many of the firms we contacted gave us a "lukewarm" reception, while Tol-O-Matic engineers expressed genuine interest in the task at hand. In fact, Tol-O-Matic actually built a custom extrusion for this actuator."

It was evident when Acist design engineers started developing early prototypes of the system that a custom actuator was needed. Enter Tol-O-Matic engineers, with new and exclusive electric linear-actuator products and a willingness to provide customization as needed on challenging projects. "We looked at using a standard Tol-O-Matic BC3 cylinder body and a standard lead screw and ball nut for the actuator," said Derek Wise, Tol-O-Matic design engineer, "but because of Acist's special requirements, we needed to work off a clean sheet of paper to build a prototype with all of the special features they wanted.

Acist's engineers defined the requirements of the actuator and the design evolved as the system developed. Design targets included:

A rugged and reliable design

  • A belt drive

  • 2,000-lb axial force capability

  • 2.8-inch/sec rod velocities

  • 5.1-inch stroke length

  • 0.010-inch positioning accuracy

  • 0.002-inch lead-screw backlash

  • 250,000 inches of lifetime travel

The cylinder body is a custom aluminum extrusion which allows component mounting from all four sides. This configuration accommodated design changes along the way, plus it furnished a versatile design platform for future product models which Acist is planning for radiology and ultrasound applications.

Unlike many actuator applications where carrying and moving a load are the primary requirements, the Tol-O-Matic rod-type actuator carries no load, but is designed to provide movement and thrust force to a syringe in the injection system. As a result, the actuator was more compact because it uses no radial bearings. A custom-designed, stainless-steel rod end transmits the actuator's motion and force to the syringe plunger and provides consistently smooth straight-line motion.

To power the actuator, Acist specifies Electrocraft (Eden Prairie, MN) brushless-dc servo motors. The NEMA-34 frame (E3629) servo motor ships directly from Electrocraft to Tol-O-Matic, where it's mounted onto the backing plate of the actuator. It provides a peak torque of 575 inch-oz.

Tol-O-Matic integrates another ten-turn, boron-wound, precision potentiometer supplied by Riverside, CA-based Bourns Inc., for extra safety. Mounted in the drive area, it provides position feedback data, and shuts the system down in the event of problems such as a broken belt. "To insure high accuracy, Tol-O-Matic calibrates each unit individually prior to shipment," explains Wise.

Two gears drive the potentiometer system. Originally designed of aluminum, one gear was redesigned with an aluminum/acetal composite to reduce the possibility of system contamination due to wear and to operate with less noise. And hard-coat, anodized belt pulleys reduce system contamination due to belt wear.

The actuator lead nut incorporates special Delrin AF antirotation keys. A new design feature for Tol-O-Matic actuators, these keys prevent the thrust rod from rotating, and they also actuate micro-switches which provide position data to the system controller. These switches shut the system down to prevent the unit from travel past end of stroke. The actuator motor mounting plate has a special access port which allows easy drive-system removal and adjustment when calibrating the actuator and performing maintenance. Finally, actuator components include special finishes such as nickel plating some steel components, and anodizing all aluminum components.

In addition to assembling the actuator and motor components for Acist, Tol-O-Matic provides three separate operating tests of the final assembly. A runout test verifies system tolerances. A second test with a dynamometer confirms current stability so there is no potential for electrical surges. A final test checks the potentiometer gears for system backlash.

"Even with all of the modifications, the final actuator design is relatively simplistic," says Wise, "but the best designs are straightforward and easy to operate. We liked it so much that we just released the RSA series of rod screw actuators. With six new sizes, we've got all kinds of new applications lined up including: third axis in gantry systems, indexers, platform tables, and others."

Other Applications

Servo-fluid injection

  • Positioning tables

  • Hydraulics and pneumatics

Engineering analysis will enter the future hand-in-hand with design

Finite element analysis should not stand apart from design because the two are intertwined, Weingarten says. When analysts and designers work together they are more efficient and more productive.

Design News: What's truly new in finite element analysis?

Weingarten: The basics haven't changed. What's new is that the majority of engineers are using Windows. More engineers are using PCs for CAD and analysis. Meanwhile, both iterative and direct solvers have improved. Many automotive users of FEA did not want to use a PC and solve their problems several times using iterative solvers--even though iterative solvers like our FFE have solved design analysis problems with more than one million degrees of freedom on a PC. So, improved direct solvers now handle their problems. Some direct solvers are up to 100 times faster than before, and that means, among other things, that engineers can solve problems as fast or faster on PCs than on Unix. Meanwhile, PC prices have dropped. In analysis, we take advantage of those trends.

FEA can't live as an island. More often than not these days, it is integrated into the mid-range CAD products engineers are increasingly using. We are primarily devoted to developing products for the mid-range field. We are bringing the capabilities of an FEA system to CAD systems. For example, we have had shells in our high-end product for use with Pro/ENGINEER. Now, we have shells for SolidWorks, and we expect to add beams, gaps, optimization and sensitivity, and other capabilities normally found in standalone FEA. This is the way of the future. We are integrating our high-end capabilities into design products, and that makes it much easier for users.

Q: Are design engineers trained to do analysis?

A: Not specifically, but that's not important with today's products. Analysis training used to be difficult, but our product is so easy to use that it's easier than developing a CAD model for basic analysis. For example, for static analysis, a user only needs to know loads and boundary conditions. Pick them and click to apply them to the model, and the program does the meshing for the basic analysis. Of course, for complicated analyses like complex assemblies or non-linear problems, you still need a specialist who is well trained, but you don't need as many as in the past.

Q: Just what does an engineer need to know to perform analysis?

A: Engineers need to know basic structural principles and how to use CAD. To help train upcoming engineers, we join with SolidWorks in donating software to universities for engineering classes. Bentley Systems and other CAD developers have also approached us to do something similar with them. As freshmen move through the curriculum, they would take courses in strength of materials, then structural analysis or dynamics or thermal, and use these tools to solve real-world engineering problems.

Q: Will design and analysis ever merge?

A: I believe that in the future analysts and designers won't be on separate islands. They shouldn't be, and the truth is that we moderns have built an artificial separation between the two functions. Analysts should be in the design group, and they should understand design just as designers should know something about analysis. When they are together, communications will be better. Working as a group, they will be more efficient than they are working separately.

Q: Do you see any breakthroughs on the horizon in analysis?

A: Windows-native CAD has been very successful. SRAC is developing Windows-native FEA. Actually, we are demonstrating such a program. It incorporates the Parasolid modeler, and shortly will include the ACIS modeler. Users with a couple of CAD products will be able to use this design-analysis tool with all their CAD products. We'll develop an API for the product. Through the API, fluids, electromagnetics, and injection-molding companies can tie into the product. Our first partner in this venture will be Unigraphics Solutions' Solid Edge. I think this will be a new dawn for design analysis.

How to chose between hydraulics and electromechanics

The case for electromechanical motion

by  Christopher Griffin, Product Sales Manager-Electromechanical Parker Hannifin Corp., Automation Actuator Div.

The idea of controlled force and motion has long been the domain of the fluid power industry, in particular hydraulics. Servo motor technology, however, has reached a stage of development where it is both cost effective and relatively easy to learn and apply. Servos, step motors, ac and dc motors are all well suited to drive lead screws, ball screws, belts and pulleys and racks and pinions. Where they excel is in the speed, repeatability and positional accuracy they can achieve.

The generally smaller form factor of electromechanical systems has opened doors to opportunities in many industries. On the smallest scale, servo-driven linear and rotary actuation systems have been important to the development of semiconductor manufacturing and testing, medical manufacturing, packaging and testing, and small electronics manufacturing. In addition to being small, these systems may be manufactured to meet clean room specifications, low noise requirements and micron-level positioning requirements.

On a larger scale, electromechanical solutions have increased the throughput and quality of a feast of packaging applications, from palletizing and box-forming to product marking, labeling and filling. The key to success in the packaging industry is a combination of the speed, torque and accuracy of electromechanical systems. This success is augmented by the growing sophistication of control systems, which extend from simple hard switch logic to PLCs and microprocessor-based multi-axis motion controllers.

The automotive industry has integrated electromechanical systems to automate many of its manufacturing and material handling processes. These systems have typically improved the achievable part or process quality.

Electromechanical solutions typically do not produce much more than 20 hp, which ultimately limits the thrusts and payloads that can be positioned. There are, however, emerging technologies that will broaden the application envelope.

Comparing hydraulics and electomechanics. We need to understand that these are two fundamentally different disciplines. Hydraulic systems produce linear motion naturally, while electromechanical systems produce rotary motion naturally. The application overlap does not enclose the extent of either technology's capabilities.

When comparing these two technologies, two aspects stand out: cost and complexity. Hydraulic systems are generally purported to be lower cost, while electromechanical systems are thought to be prohibitively expensive and require a control systems degree to figure out. For the application designer to be most effective, he or she really needs to gauge the needs of the application and select the most suitable technology. Both technologies can move loads from position to position. The differences lie in cost, load, environment and accuracy.

Cost. Hydraulic systems, in fact, can be more expensive in lower power applications, due mainly to infrastructure costs, such as power units, hoses and valves. Electromechanical systems, obviously, require only a power supply, although the wiring involved is no less complex than a hydraulic circuit. As horsepower increases, hydraulic systems become more cost-effective, as the infrastructure doesn't change. This is often referred to as "power on demand." Electromechanical systems require increasingly expensive power electronics and mechanical components, such as ball screws and bearings.

Load. The power density of hydraulic systems makes them extremely efficient. Hydraulics can produce tremendous amounts of thrust and generate considerable power without transmitting power from one mechanism to another. Electromechanical systems must by design transmit power from device to device, such as rotary motor to lead screw. The reduction in efficiency, the need for a coupling, and the prohibitive cost of high power mechanical components limit the feasibility of the electromechanical solution in high power applications.

Complexity. Multiple position applications, where a position feedback device is necessary, require a competent understanding of the control system and the mechanics it is tied to. Hydraulic position control normally centers itself on a position transducer and proportional valve. Producing thrust and hence motion in a hydraulic system is non-linear, due to fluid dynamics. Tuning such a system to reach a position quickly and in a repeatable fashion requires experience. Tuning an electromechanical system, where thrust ( in the form of motor torque ) is linear, might require a half day of training and a good grasp of the particular needs of the application. Step motor systems in fact require no tuning, although they still provide reliable and repeatable positioning. Newer servo system products almost invariably include an 'auto-tuning' feature that accepts system parameters and calculates tuning gains automatically.

Accuracy. Digital position feedback in the form of optical encoders and scales makes micron-level positioning possible in electromechanical systems. With variable displacement transducers onboard, hydraulic control systems typically cannot achieve much more than 0.003-inch repeatability.

Environment. Pressure vessels, such as hydraulic products, are inherently rugged. They find themselves in the harshest environments: extreme temperatures, outdoors, and in mobile applications. Unlike electromechanical systems, they are unaffected by dirty environments and can operate where explosion-proof motion is needed. Electromechanical systems run quieter, require less infrastructure, and can be designed to operate in clean room environments.

As servo technology costs fall, certain products are becoming more accessible. Brushless servo motors are becoming more common in applications typically held by brush motors and step motors. Linear servos are viable alternatives to screw-driven positioners, offering higher speeds and higher throughput without the lead error of the screw. While screw technology isn't new, there have been advances in design that enhance performance. High lead ball screws allow for high linear speeds without increasing the screw diameter. Roller screw technology, in which a set of planetary screws replaces the ball nut, can produce thrusts well over 1,000,000 lb-ft.

The case for hydraulic motion

by  Richard H. Woodring Electrohydraulic Business Unit Manager, Parker Hydraulic Valve Div.

Today's controls engineer enjoys the benefit of a variety of methods for generating mechanical motion and/or force in his machine design. Included in these are pneumatic, hydraulic, and a number of electromechanical actuator devices. The options available to a designer can create confusion over which provides the optimal solution for a given application. Recently the industry has given significant publicity to advances in electro-mechanical control technology. The author has encountered many machine designers who select electromechanical options because they believe they're smaller, quieter, cleaner, more reliable, more controllable or simply more "state of the art."

If one critically evaluates the variety of motion control requirements available, he will see that there is no "one-size-fits-all" solution. Every technology has advantages and limitations. The intent of this article is not to focus on the weaknesses of any competing motion control technology, but rather to explore the attributes that make hydraulic motion control an attractive option for the controls engineer.

Hydraulic control systems have gained a reputation for being noisy, dirty, and--in some circles--old-fashioned. In recent years, the hydraulic control component industry has made numerous advances in addressing these issues. A properly designed and maintained hydraulic system can be quiet, clean, efficient and relatively easy to maintain.

Without a doubt, the most significant advantage of hydraulic motion control is its ability to concentrate high levels of horsepower, torque and/or force in a small package. As a rule of thumb, a hydraulic motor will deliver 1 hp per lb of weight compared to only 1/16 hp per lb for an electric motor. The rotary actuator--a simple device that converts the linear motion of a hydraulic cylinder into a rotary motion via an integral rack and pinion arrangement--can deliver 900 inch-lb of torque in an 11-lb package compared to 30 inch-lb for a dc motor drive of similar weight.

Hydraulic control's advantages become readily apparent when one looks at linear motion or the generation of force or thrust. In today's market, it's very common to find hydraulic pumps, control valves and actuator components that are rated at operating pressures of 5000 psi (350 bar). At this pressure level, a relatively compact 2-inch diameter hydraulic cylinder will generate over 7 tons of force. By the laws of geometry, this force generation capability grows by the square of the increase in its diameter, leaving the electromechanical solution in the dust.

In addition to the raw force generation of the hydraulic actuator, the hydraulic actuator also exhibits linear velocity capabilities that approach 2 meters/second compared to less than one meter per second for its electromechanical cousin. The actuator's high thrust-generation capability allows it to accelerate and decelerate heavy loads much more effectively than can an electromechanical actuator.

The positioning capabilities of an electrohydraulic actuator system vary significantly from application to application. Factors like load mass, frictional characteristics, load velocities, machine frame stiffness, control valve bandwidth, hydraulic plumbing compliance and sophistication of the control electronics all interact to affect the application's positioning accuracy. We are, however, aware of electrohydraulically controlled machine tool feed stations that are maintaining positional tolerances of ± 0.0002 inches, which is comparable to typical electromechanical solutions with a similar stroke capability.

The hydraulic actuator is also self-lubricated by the hydraulic fluid used in the system, another inherent advantage. When proper filtration techniques are used to maintain fluid cleanliness, one can expect the actuator to provide tens of thousands of hours of wear-free, trouble-free service. The electromechanical actuator typically incorporates a lead-screw or ball-screw mechanism that is susceptible to lack of lubrication, external contaminant ingression and ball-screw loading.

In the past decade there have been numerous advances in motion profile control capability for electrohydraulic actuators. The advent of high bandwidth proportional valves and solenoid operated servovalves has significantly advanced the application of electronic motion control for hydraulic actuator systems. Admittedly, developments in the electromechanical controls industry have had a significant, positive impact in improving control capability levels of electrohydraulic systems. Today's state of the art high-bandwidth solenoid servo proportional valves use high-speed electronic switching solenoid drive techniques developed and perfected by the electric servomotor industry. In fact, the sophisticated microprocessor based motion and force controllers used today for electrohydraulic profiling can trace their roots to devices designed for the control of servo and stepper motors.

Yet, having acknowledged that the electromechanical industry has provided some tips on how to "fight," we might put the gloves back on and go a couple of more rounds in our friendly match. In addition to the advances in electronic- and hydraulic-control technology discussed above, the industry has made other improvements to remain in fighting form. Designers have continued to improve the hydraulic pump's control features, efficiency and sound levels. Variable volume pumps are now available with a full compliment of electronic flow and pressure controls. Volumetric efficiencies are in the mid- to upper-90 percentile range, and well-designed hydraulic power units operate in the 65-70 dB sound level range. The hydraulic control system now also has an added advantage when heat and noise are an issue. The power unit can be located remotely from the hydraulic actuator. This effectively isolates hydraulic noise and also allows for any heat generated at the actuator location to be removed through the exchange of fluid in the actuator. By contrast, electromechanical actuator installations require control electronics to dissipate any heat generated by the actuator's braking action.

The hydraulic controls industry has also addressed the problem of external fluid leakage. The commonly used tapered pipe thread is gradually being replaced with straight thread fittings fitted with elastomeric seals. Wherever feasible, dynamic seals are being eliminated in hydraulic component designs. Effective use of electrohydraulic control devices is reducing the hydraulic shock that often results in external leakage at fittings and hydraulic line connections. Finally, expanding use of the popular hydraulic integrated circuit has significantly reduced the number of potential leak points in the systems. In addition, we must credit the machine designers and manufacturers; in recent years, we have seen a rededication to the design of clean, leak-free, hydraulically operated machines.

You should realize, however, that we do not advocate hydraulic actuation as the optimum solution for all motion control applications. It is, however, the solution of choice in those environments subject to temperature extremes and high levels of dirt and/or moisture. In such environments, the hydraulic solution is equal to the electromechanical in terms of motion profiling and position control. Throw in a requirement of providing high levels of torque, force, power or thrust in a small, reliable package, and hydraulic control technology wins hands down. Moreover, a properly designed system can overcome the frequently cited problems of external fluid leakage and operating environment noise pollution.

Hot products

Non-contact sensors unaffected by echo

HiTECH Technologies' new line of compact, non-contact ultrasonic proximity sensors are based on echo pulse technology. The SonicLaserTM Ultrasonic Proximity Switches come in 18 different models and feature a patented, concentrated narrow beam angle of only 2.5 degrees off-center axis for reliable operation unaffected by interference from false echoes caused by surrounding objects. Measuring ranges vary from 3.28 to 26.25 ft depending on the model selected. The sensors operate in temperatures from -20 to 140F. Accuracy ranges from 0.08 to 0.2 inch. Applications include non-contact sensing of height, distance, continuity, presence, or absence of objects on trucks or railcars, or lift trucks and assembly lines and conveyors.
HiTECH Technologies Inc., Product Code 4453

Transducer works in tough environments

Setra Systems Inc. introduces the Model GCT-225, a low-cost, ultra-high-purity pressure transducer for pressure-measurement applications that require insensitivity to environmental extremes, including high purity gas delivery systems, gas cabinets, and semiconductor process tools. The GCT-225 offers accuracy of ±0.25% FS and full scale pressure output of 0.2 to 5.2V dc or 4-20 mA output. The transducer measures gauge and absolute pressures from 0-25 to 0-3,000 psig or psia and compound pressures of -14.7-25 to -14.7-3,000 psig. A reduced height of 4.25 inches enables the GCT-225 to fit many applications, and its low cavity volume of 0.22 inch3 means the device is easily purged.
Setra Systems Inc. Product Code 4449

Steady, dry pressure gauges

Pressure gauges are getting a whole new look as Dresser Industries introduces a dry pressure gauge steady as a liquid-filled gauge--the Ashcroft Duragauge® PLUS! Liquid-filled gauges have been the standard for tough applications for 20 years, due to their reliability under high pulsation and vibration. But, says Dresser, they are harder to maintain than dry gauges and more expensive. The Duragauge handles vibration and pulsation better than standard dry gauges and fills a performance gap for those whose dry gauges may not last as long due to wear. The company reports that beta testing shows the gauge can last 100% longer than the conventional dry gauges. In addition, Duragauge PLUS! provides a steady pointer just as liquid-filled, but costs less. The patent-pending Duragauge PLUS! pressure gauge is certified at ±0.5% full-scale accuracy. Ranges include: 0/60 to 0/100,000 psi, 0/100 to 0/400,000 kPa, and 0/4 to 0/6,000 kg/cm2. Tube materials include phosphor bronze, 4130 alloy steel, 316 SS and Monel 400.
Dresser Industries, Instrument Div., Product Code 4447

Say cheese for new uncooled IR cameras

Inframetrics (North Billerica, MA) introduces three new uncooled infrared focal plane array (FPA) thermographics cameras--Models PM 195, 295, and 395 of the ThermaCAM® X95 Series. The uncooled FPA detector technology includes what the company says is the first microbolometer detector designed specifically for precision temperature measurement in an uncooled IR imaging system. The ThermaCAM ULTRA X95 Systems provide long wave (8 to 12 micron) response, which makes them useful for general predictive and preventive maintenance work and outdoor inspections in sunlight. The cameras use a temperature-controlled detector radiation shield (patent pending), allowing extremely stable operation, expanded measurement ranges, and a significantly reduced need for internal image uniformity corrections. The device is palm-size and weighs just 4.4 lb.
Inframetrics Inc., Product Code 4450

Ready-to-use test software for wireless manufacturers

From a joint development with Hewlett-Packard and CommQuest Technologies comes the Total System SolutionTM for wireless manufacturers. The software offers what CommQuest says is the industry's first turnkey in-line production testing solution. The system bundles CommQuest custom test software, optimized for its chipsets, with Hewlett-Packard test equipment. The company claims the ready-to-use software package cuts up to 50% of cost from the testing process, and shaves months from design cycles by eliminating the need for custom software design.
CommQuest Technologies, Product Code 4451

Digital phosphor oscilloscope

Tektronix Inc. introduces a digital phosphor oscilloscope (DPO) that enables engineers to see, store, and analyze complex electronic signals. Tektronix's DPO is based on patented DPXTM technology. The company says DPX provides up to 1,000 times more signal data than digital storage oscilloscopes (DSOs), giving engineers more insight into the subtle patterns and behavioral variations of signals. DPOs differ from analog real-time oscilloscopes (ARTs) and DSOs, in that the digital phosphor oscilloscopes display, store, and analyze in real-time, using three dimensions of signal information: amplitude, time, and the distribution of amplitude over time. The benefit of this third dimension is an interpretation of the signal dynamics, including instantaneous changes in the signal and the frequency of occurrence. ARTs can display these three dimensions, but they cannot store or analyze them. Traditional DSOs only work with amplitude and time information, capturing infrequent snap-shots of less than 1% of the available signals.
Tektronix Inc., Product Code 4448.

Rubber know-how nutures plastic peer

When an industry-leading provider of precision-made rubber, plastic, and die-cast components decides to spin-off its plastics operations into a separate entity, it usually does so with a vision for innovation and growth. That's the scenario for QMR Plastics (River Falls, WI).

The firm had its birth as a division in 1995. Since that time, it has doubled its sales volume through a combination of leading-edge technology, factory-of-the-future manufacturing operations, and highly motivated employees. The newcomer follows in the footsteps of its companion division, Minnesota Rubber (Minneapolis), which built its reputation on 50 years of experience in engineering, designing, compounding and manufacturing custom-molded rubber and plastic components.

QMR Plastics and Minnesota Rubber form part of Quadion Corp., also headquartered in Minneapolis. Tool Products, a manufacturer of aluminum and ZA die-cast parts, comprises the third spoke of the corporate wheel.

The spin-off of QMR Plastics from Minnesota Rubber into a separate operating company makes sense, both from Quadion's standpoint and for the customers. In many instances, molding components of either plastic or rubber can provide a distinct advantage in function and economics. The expertise provided by the sister companies enables the customer to select the optimum material for the application. Such a choice gave Quadion an opportunity for increased profits. Hence the symbiotic split.

Early in 1995, QMR Plastics moved into a 35,000-sq-ft, state-of-the-art facility. Housing two dozen automated presses with capacities from 28 to 200 tons, the company designed its operations and processes with QS 9000 and ISO 9002 certification in mind. Both were achieved last year.

"We had a goal of defect-free, on-time performance, so our facilities and the people operating them had to be the best," says Darwin Nogelmeier, director of sales.

Design engineering aid. But QMR Plastics offers customers much more than a nice facility and modern machinery to produce their components. Customer services include: engineering design support, on-site mold repair and maintenance, multiple-part assembly, and hot runner/manifold tooling.

Customers include world-class OEMs in the appliance, agricultural, automotive, and fluid power industries. Alphabetically speaking, they run the gamut from AlliedSignal and Kodak to Square D.

For these customers, QMR Plastics' technical personnel provide in-house system and manufacturing engineering assistance. These technicians can lend engineering support for assemblies, subassemblies, custom seals, rubber-to-thermoplastic (TPE) conversions, and metal-to-plastic conversions.

At the customer's disposal are high-end CAD/CAM systems that can receive 2D and 3D file formats geared to reducing the customer's part-design cycle time. Functional and life-cycle part testing services are available, as are complete tool design and construction specialties. This includes the entire management of all tool-making steps from design to sampling. In addition, the company has 18 technical sales support personnel strategically located in 12 regional offices to further assist customers. (Visit on the Internet.)

In addition, QMR Plastics has as one of its strengths a great deal of experience in hot-manifold and hot-runner technologies. The hot-manifold process in particular has a huge potential for growth. It offers increased production due to faster cycle times, as well as minimal regrind generation and less chance for material contamination.

The hot-runner technology adapts especially well to PEEK (polyetheretherketone) processing, The semi-crystalline polymer won't dissolve in common solvents and resists a wide range of organic and inorganic liquids. Properly compounded, the material's friction properties make it a good candidate for bearing-type applications. For instance, the material can remain in service for thousands of hours at temperatures in excess of 250C in steam or high-pressure water environments. It also has a V-O flammability rating down to a cross section of 0.057 inch--without the need for an additive.

A seal ring for an automatic transmission offers a good example of PEEK's capabilities. The double-step joint ring (one of four designs) costs less than the metal ring it replaces. The gap in the joint accommodates thermal expansion, with the overlapping section maintaining a controlled seal. In addition, the gap maintains the critical flow of oil through the transmission, providing more precise control in shifting.

Such designs have helped QMR Plastics enjoy a robust growth in its short lifetime. But it's only a sampling of even greater things to come, according to Director of Sales Nogelmeier.

Star status. QMR Plastics' new facility got rave reviews in "Factories for the Future," an article that appeared in the November 1995 issue of Progressive Architecture (PA). "The interior...exudes the vitality of a great railroad station--airy and expansive, with long-span exposed trusses supporting the roof," the story reads. "Simple shed dormers, 88 ft long, let light wash down on the white-painted metal structure."

From a strictly practical point of view, the factory features high-quality metal-halide lamps for good color rendition of its plastics products. The PA editor also notes that "the most impressive thing about QMR Plastics is that employees working at the plastic injection molding machines can look straight out through generous expanses of glass to a slope planted with wildflowers, with a stand of trees at its crest."

A tunnel 6-ft wide and 7-ft deep houses utilities, allowing quick hookups to machinery, air handling, sprinkler systems and lighting. Structural support (pre-engineered trusses) are concentrated in the 12 ft between the overhead crane and the ceiling.

The PA reporter adds that such facilities hold lessons for today's businesses that are tempted to cut initial building costs to the bone. Cheap buildings, the article argues, hobble companies that wont to get the best out of their tools and their employees. QMR Plastics has done just that to the satisfaction of their growing list of customers.

Custom designs drive QMR Plastics' success

If a quick start is your goal, it'll happen with the aid of a primer bulb…providing you're starting a small gasoline engine for a weed trimmer, snow blower, or some other type of lawn and garden equipment. Pressing on the bulb causes pressure that forces gasoline into the intake of the engine, aiding in quick starting. A thermoplastic urethane (TPU) was the only material that met the stringent requirements of the application, including:

Enabling the bulb to withstand repeated flexing without distortion.

  • Good ozone and weather-resistant characteristics.

  • Excellent compatibility with gasoline.

An added benefit: the consumer sees the gasoline as it flows.

Although finding a chemical bond between a thermoplastic elastomer (TPE) and metal has been an ongoing challenge in the elastomeric world, QMR Plastics developed a TPE-to-metal bonding agent with superior performance for a quick-disconnect coupling used in natural gas utility vehicles. The coupling acts as the female end of the handle in the quick-disconnect application. It consists of Santoprene® chemically and mechanically bonded to a stainless-steel sleeve. The mechanical bond is achieved through knurling on the O.D. of the sleeve. In a continuous effort to improve the quality of the bond, a QMR engineer developed a unique process that successfully provides an incredibly strong bond between the Santoprene and the metal.

Also, consider the push-button component for Eastman Kodak'sTM Fun SaverTM Sport one-time-use camera. QMR Plastics custom-colored the Santoprene material to Kodak's specifications. Because of the camera's underwater use, the push button had to achieve sealing capabilities of 12 psi. To accommodate this, the part was formed with an enlarged bead on the O.D. This design, in combination with the TPE's relatively good compression set, provided Kodak with a flawless seal.

Show stoppers

Show stoppers

With 1,450 exhibitors from 50 countries and 120,000 attendees, the century's final Int'l Machine Tool Show served as proof that the industry is stronger than it's been for two decades. The show, which ran from September 9-16 at Chicago's McCormick Place, also proved that advanced motion control technology has taken a firm grip on the industry. Five-axis systems, high-speed machinery, linear motors, and data buses headed the list of key technologies at the show. Cincinnati Milacron, for example, was one of several exhibitors that rolled out a five-axis machining center. Milacron's Lancer V5-2000, a five-axis, five-sided CNC machining center, joins the company's Magnum H5-800, another five-axis system that offers five-sided contouring capability ...The high-tech motion control theme also took a unique turn at the Wisconsin Machine Tool booth, where the company introduced its R665 machining center. The system was designed and built in partnership with Bosch Automation Technology, which provided CNC controls, servo drives, motors, hydraulics, pneumatics, and technical expertise.

Getting on the bus

Data bus technology also took a significant turn as Ormec announced its new ServoWire Drive Network, which uses the open standard IEEE-1394 to create a 200-Mbps digital network for industrial servodrives...GE Fanuc introduced the Series 15i, said to be the highest performing CNC in the world. Designed for high-speed, high-precision milling applications, it accommodates up to 24 axes ...Mitsubishi Electric Automation announced the availability of six CNCs with 64-bit processor architecture, designed to speed machining operations. Known as the M600 CNC family, the units can be used in applications ranging from 11 to 21 axes ...Rockwell Automation showed the 9/PC, the first PC-based CNC offering open interface. The unit is SERCOS and DeviceNet compatible ...Indramat showed off its ECODRIVE-03, a compact ac servo drive that integrates motion control, spindle control, amplifier, power supply, and I/O in a single, compact unit ...Star Linear displayed a ball screw unit with a stationary screw and rotating nut. The inherent stiffness enables it to be operated at speeds up to 4,000 rpm, versus 2,500 rpm for conventional ball screws ...Rimtec rolled out the ADS servo coupling for digital drives. Its unit eliminates resonance problems that sometimes occur during fast acceleration and deceleration associated with servo drives.

Added life, lower maintenance

THK America displayed its SSR LM Guide, which isolates bearing balls in an elastomeric cage to reduce maintenance and noise ...Parker Hannifin introduced Fulflo Trubind Absorbent Cartridges that extend machine tool life in point-of-use coolant applications ...Nook Industries demonstrated its Power-Trac internal return ball nuts, which offer a compact profile for linear motion in machine tools ...Firestone Industrial Products showed an air-over-water table made in conjunction with Lee Engineering Co. The table is less costly than comparable hydraulic tables.

Bearing down on competition

Thomson Industries announced its Super Smart Ball BushingTM bearing line in sizes that meet all metric and inch standards. The company says the bearings have six times the travel life of conventional bearings. Small bearing sizes allow downsizing motion control equipment or increased load or life ...Versatility for cost effectiveness is the key to Carboloy's new Multi-Directional Turning (MDT) tools. Different MDT toolholders combine with a single indexable carbide insert, available in several widths. Patented serrated teeth on both insert and holder pocket provide stronger insert retention. ...The Heidenhain Specto ST 12 incremental length gauge's small size allows grouping several together for multipoint inspection. Measuring length is 12 mm with an accuracy of plus or minus 1 micron. The grating-on-glass-based device provides stable measurement over longer time, eliminating recalibration ...Softech introduced Prospector 3.0, which permits mold and die shops to move decisions from the CAM room to the shop floor--from product design analysis to toolpath verification and optimization--speeding mold fabrication. Machinists can adapt a cutting project to real-time consideration, reducing or eliminating human error. Knowledge-based software allows digital development of moldmaking, using industry "best practices" in creating cutting paths ...A unique machine-tool spindle force sensor allows OptiMil version 3.0 from OMAT Control Technologies to automatically adjust the cutting feed rate, reducing cycle times and extending tool life. ...Hydromat noted the speed and flexibility of its new WindowsTM NT CNC control. Change-overs for quick-response, just-in-time short production runs, as well as high-volume machining applications, can be accommodated via fully programmable speed and feeds, quick-release collets, and presettable toolheads ...Completely software-based OpenC(R) from MDSITM was highlighted. This single Intel processor PC package does not require any proprietary hardware for retrofitting of any CNC machine tool or integration into manufacturing execution systems ...Gradient Lens Corp. showed its Hawkeye(R) SuperslimTM borescope. Key to the inspection tool's low cost are reduced numbers of optical elements, thanks to gradient-index (GRIN) optical materials. These bend light continuously within the entire length of material ...SDRC introduced the third version of its I-DEAS Artisan Series with its new CAM component, Artisan ManufacturingTM. In addition to Manufacturing, the package includes modules for Sheet Metal, Mechanisms, and a Fastener Catalogue. ...Lumonics Laserdyne(R) 790 BeamDirector(R) permits specifying fewer parts for complex assemblies. Its five axis laser beam motion, rigidity, and automatic focusing allow a part to remain stationary during processing for greater accuracy, repeatability, and reduced set-up time.