Engineering News 7489

CAD, rapid prototyping power design time

Chrysler continues to beat the clock by combining CAD software with rapid prototyping to create a continuous, paperless design process

by Anna Allen, Staff Editor

Auburn Hills, MI--Decrease design time. Engineers at Chrysler have done just that, consistently, from the development of the 1993 Intrepid/Concorde/Vision--which took 39 months, to one of their more recent automobiles, the 1998 Dodge Durango, which took 23 months.

And now, using a combination of 3D CAD software and rapid prototyping machines, Chrysler continues along this paperless path--creating models for power-train components in half the time and saving an estimated $5 million in development costs.

The most dramatic example is the cylinder head for a new 1.6l engine for use in future small cars--currently being developed by Chrysler for the Chrysler-BMW joint venture. The model for the cylinder head was developed in four months, five months faster than any other cylinder head Chrysler has developed. Engineers also reduced prototype tooling time from 16 to eight weeks.

The tools that made this possible: CATIA 4.1.9 3D software from IBM Dassault Systems and the FDM Quantum rapid prototyping machine from Stratasys Inc. (Eden Prairie, MN), which includes QuickSlice software. Both allow engineers to travel from the early design stages of product development through to final production and assembly-line layout with a single workstation that accommodates both QuickSlice and CATIA.

Previously, computer development of parts was limited to points, lines, and surfaces. Now, through solid modeling, Chrysler engineers can create mathematical data for solid, 3D parts. Computer images are then transferred in mathematical data to a rapid-prototyping machine, where the parts are made in hours rather than days or weeks.

"Using 3D solid modeling packages, such as CATIA, allow us to include the draft of the part and tool parting lines into the component design," says Laura Rosenbaum, product engineer of the Joint Venture Engine Engineering Dept. at the Chrysler Technology Center. She comments that the benefits of this include shorter tooling development time and more accurate tool-to-part representation.

After part modeling is completed, QuickSlice data is programmed into the FDM Quantum workstation where the part is directly created. "As you can imagine, these parts are much more exact and that means better quality for our customers," says Doug Livermore, executive engineer, Small Car Platform Engine Engineering. "We can create 3D models in half the time, and we can get that information to tooling suppliers up to five times faster, depending on the model size."

Says Rosenbaum, "The benefit of having this rapid-prototype part is having a physical part for evaluation." For example, when doing assembly trials engineers can physically try out the assembly and see the interface. Rosenbaum says that this complements what can be discovered or designed in 3D solid packages.

"The use of 3D solid-modeling programs, such as CATIA, in conjunction with rapid prototyping, yield several benefits," says Rosenbaum. "Most significantly, the rapid prototypes serve as a visual communication tool for team members and allow the illustration of a design issue to those who do not have the 3D solid-modeling capability."

Using this technology combination, Chrysler was able to deliver the cylinder head to machine shops and production machine tool builders 14 weeks ahead of schedule. Rosenbaum also says that the use of both solid modeling and rapid prototyping has improved communication between engineers and Chrysler's many overseas customers.

As far as the future of design is concerned at Chrysler, Rosenbaum comments that "the intent is to roll this process into more Chrysler programs."

What this means to you

Rapid Prototyping System Passes the Test

Engineers at Chrysler beta-tested the FDM Quantum rapid prototyping system for use in developing powertrain components for its automobiles.

"Chrysler was an ideal choice for beta-testing the FDM Quantum," says Jon Cobb, Stratasys vice president of marketing. "The Chrysler Technology Center has embraced rapid prototyping as an integral element to its digital design and manufacturing process, along with CATIA(R) software."

The system incorporates MagnaDrive technology, which the company says allows fast throughput and superior part quality, and features a build envelope of 600 3 500 3 600 mm. The FDM Quantum maintains accuracy of plus or minus 0.127 to 127 mm, and plus or minus 0.0015 mm/mm to 60 mm. In addition, the models can be used as functional prototypes, tooling patterns, and masters.

MagnaDrive uses the same technology as used in high-accuracy, pick-and-place machines for semiconductor manufacturing. An extrusion head, containing an electro-magnetic motion-control unit, is pulled toward a steel plate above (see diagram). The head is simultaneously pushed away from the plate's surface by a cushion of air. This type of air bearing allows the head to move at a high velocity, as friction approaches zero.

According to Paul Williams, manager of body-design verification engineering in Chrysler's vehicle engineering operations, "The FDM Quantum was installed and up and running very quickly. We were able to start using Quantum to reduce our backlog immediately. And our internal customers have been very satisfied with the ABS parts we have built."

Novel rebuildable lip seal lets users replace worn parts

Laguna Niguel, CA--Would you throw away your car if you needed new tires? Of course not. However, engineers routinely throw away metal-cased lip seals when the sealing elements, or "lips," wear away--case and all.

To solve this problem, the Furon Co. has responded with the OmniLip-RS rebuildable lip seal. It consists of a reusable metal seal case; one or more replaceable sealing elements or lips, typically made of PTFE; mechanical spacer or spacers which are made of the same material as the seal case; screw fasteners that hold the seal case or body in place; and rubber O-rings on the assembly's outside diameter.

The way users typically install a metal-cased seal involves force-fitting it into a board, so the seal is bigger than the housing, which means it takes an arbor press or hammer to install the seal, says Jim Goodman, senior design engineer for Furon.

"Any time you have to replace a seal, you have to take the unit apart, then remove the seal from the housing," he adds. "Because the seal was under a press fit, and possibly under a sealant which prevents leakage, it is difficult to get out. It is very common to scuff up or damage the housing."

When the OmniLip-RS seal's lips, the parts of the seal that wear from frictional heat and rubbing, need replacement, the user unbolts the face plate of the rebuildable seal portion, takes the worn PTFE components out, replaces them with new components, and bolts the assembly back together, Goodman says.

With the rebuildable seal, once the user installs the seal body for the first time, it does not have to be removed from the housing ever. Downtime is minimized, and housing rework does not exist. "You never have to remove the metal seal portion from the metal housing it's installed in," he adds.

The lips are typically made of PTFE, a material that Furon chose, Goodman says, because, unlike rubber materials, it is "inert to just about everything."

"You'd have to go a long way to find something that degrades PTFE," he adds.

Components made of PTFE can also handle higher system pressures than those made of rubber materials, have large diameters, and can run at higher velocities. PTFE can run in a dry-type application, because it is non-stick.

Designers can select several materials for the seal's metal case, including low-carbon steel, aluminum, or stainless steel compositions 304, 316, and 321. Typically, the casing is made of the same material as the hardware so there is no thermal mismatch, Goodman says.

Specific applications sometimes call for other metal casing materials. "We can make the housing out of just about any material that can be machined," Goodman says.

Because the user only has to buy the metal portion of the seal once, more exotic materials, such as inconel which is corrosion-resistant and features high-temperature capability but is expensive, can be used. "It's a one-time buy," he adds.

Because of the seal's rebuildability, it is suited for applications such as the robotics industry, where machines are difficult to take apart. Other applications include equipment mixers, where parts have to be replaced periodically.

Goodman says Furon is not going into an area that is unknown. "The sealing portion remains the same. It just gives you options you didn't have in the past, such as easy disassembly of the seal, and it's a lower-cost product in the long haul."

Virtual company sells paperless products

by Laurie Ann Toupin, Associate Editor

Medinah, IL--A virtual company producing paperless products--if this is the engineering company of the future, then the future is here. Meet Visualize Inc., where mechanical engineers Michael Pelland and Thomas Wozny, software developer David Sprowls, and solution expert Raymond Pawlowski help people manufacture complex, compound shapes which are otherwise difficult, if not impossible, to produce.

Using the Internet's fullest capabilities, ftp sites, web browsers, plus multiple CAD packages, and the expertise of a multitude of small companies, Visualize produces toolable electronic models, guaranteeing immediate manufacturability.

Visualize is the outcome of the world's emphasis on appearance. "Form is a dominant feature in the nineties and will be on into the next century," says Pelland, owner of Visualize. But what looks good on paper or in a graphics program may not be easy to tool.

Take the Skip Doctor music CD Polisher, for instance. When the CAD company hired by Digital Innovations failed to produce a functional prototype of the Skip Doctor due to its complex design, Digital called Visualize.

Using Solid Designer from CoCreate, Pelland nailed the design in one week. Pelland included details such as drafts, blends, even parting lines. The surfaces have to be drafted at the proper angle, he says, to produce a smooth textured surface. "This is so when the tool opens, the piece part easily pops out," he says. The blends are important so when the pieces are cut, the tooler knows exactly what mill size to use to machine or hog out parts.

Pelland built other features, such as trigger mechanisms, ribs for the gears, and the rotating axle shaft into the design. "We are trying to control part manufacturing based solely on solid models," says Pelland. "This way, you get exactly what you see on the screen."

The end product: an electronic file that contains all of the information required for the person who will tool the part. Visualize will even provide the tooling company if the customer requests.

Visualize often works with other companies, via cyberspace, to complete a job. "We use all modern technology, such as an ftp site, to transfer all our data electronically," he says. "Not a single drawing is generated, unless the customer asks for it." Even for the Skip Doctor, where part of the tooling was done in the Far East and part in Portugal, not a single drawing exchanged hands. "We are basically using the Internet and the web as a PDM tool for people to view and approve our design," Pelland says.

To help customers with the transition to electronic production, Visualize wrote a software package that allows clients to log on with their laptop, palm pilot, or other computer system via a web browser and view the product development process. With Product Development Viewing or PDV software, the customer can download and examine all the pertinent project data independent of the CAD system used by either themselves or the design developers. PDV also encapsulates other aspects of the product design process, such as note taking, vendor selection, and data exchange.

Visualize asks its customers to sign off on designs with VRML files generated from solid modeling packages. These are viewed and inspected via a web browser.

For one bottle design, Visualize generated 16 VRML files in a day. By evening, the model was complete. If the changes had been communicated via mail or fax, the pertinent information wouldn't have been exchanged and "it would have taken us seven times as long to finish the project," says Pelland.

Hybrid/electric minibus delivers clean urban transport

Gretz-Armainvilliers, France--Faced with stringent air-quality laws and centuries-old urban centers with narrow, twisting streets, the French may have a solution to both problems. Working with coachbuilder Gruau (Laval, France), the French engineering company Ponticelli Freres has designed and produced a special hybrid/electric minibus that offers clean, quiet urban transport.

The minibus, called the Oreos 55, comes in two versions--an all-electric model and one that runs on either electricity or LPG gas, making both nearly emission-free. The bus measures just 25.3-ft (7.7m) long and 7.2-ft (2.2m) wide, yet can hold from 53-55 passengers. Power steering gives the bus a curb-to-curb turning radius of only 21.4 ft (6.6m). Its low ground clearance of just more than 13 inches enables easy access for passengers entering or exiting the bus.

The 520V, 80 A-hr, nickel-cadmium battery allows the bus to reach a maximum speed of 55 km/h (34 mph). The bus has two LPG tanks that hold 80l each (21 gal). The LPG motor recharges the battery so that the bus never has to stop for recharging. If the bus runs only on the LPG engine, it would have a maximum speed of 25 km/h (15.5) mph. The combination of the two power sources gives the minibus its intra-urban capability.

The design focuses on both passenger and driver comfort. For example, the driving station features an easy-to-read dashboard design and excellent vision ahead and behind. Liquid-crystal panels on the front and side also make destinations easy to read.

The all-electric version weighs 12 metric tons, the hybrid version 13 metric tons. Depending on accessories, the minibus costs from 2 to 3 million French francs, or about $364,000 to $545,000.

CATIA Version 5 takes the Windows NT Stage

by Katherine Tyrka, France

Paris--Dassault Systemes has announced its commitment to Windows NT with its next-generation software Catia Version 5. Positioned as both a UNIX and native NT application, the software will deliver exactly the same functionality on both platforms, says Dassault Systemes.

First releases of the software line are scheduled this month and will include the core mechanical and surface design, and assembly and drafting applications. Subsequent releases of Version 5 are planned at a more than biannual rate.

Previewed at MICAD and CeBIT last March, Catia Version 5 uses standards such as C++, object-oriented programming, STEP, and OpenGL. Catia Version 5 is designed to seamlessly join Dassault Systemes' ENOVIA Product Development Management lines and CATweb, for a completely digital enterprise.

Catia Version 5 will be completely compatible with Catia Version 4, allowing users to take on Version 5 gradually, application by application.

"The launch of Catia Version 5 on Windows NT is an important move for Dassault Systemes," says Marc Halpern of computer research and consulting company D.H. Brown (Port Chester, NY). "While UNIX will remain important over the foreseeable future, Windows NT is winning the desktop and Dassault cannot afford to miss the opportunity."

Dassault Systemes plans to continue the biannual software releases of Version 4 even after the new version has been launched.

Color sensor keeps figure heads facing forward

Schaumburg, IL--Picture your child opening a new LEGO set and finding a miniature figure with his head facing backwards. At LEGO Systems Inc. (Enfield, CT), this scary scenario was exactly what the company wanted to avoid.

LEGO produces upwards of 31 million miniature figures a year, which are packaged along with LEGO sets. Making sure the heads face forward was not a major problem when the heads were opaque.

LEGO introduced transparent and translucent heads, which the existing system, which incorporated a servo, was not designed to detect. The automation challenge became making sure the heads face forward when placed on the bodies. The company tried vision and laser solutions, but these technologies were not able to detect the transparent and translucent heads as they looked directly through the heads, according to Rick Passaro, controls engineer for Omron Electronics Inc.

Passaro brought LEGO Omron's newest optic sensor, the E3MC red, green, and blue (RGB) sensor. LEGO was able to teach the sensor the difference between whatever the head background was and whatever the background was including the face, and adjust how tightly to measure this difference, he says.

The E3MC sensor LEGO uses is a fiber version, so a remote fiber head is placed into the machine. The sensor is mounted out where engineers have access to it, and is connected fiber-optically to where they can see the heads inside the machine, Passaro adds.

The bodies and heads come down the assembly line separately. A rotating device spins the heads until the sensor picks up the head facing forward. The machine then places the head onto the body and moves on to the next figure, Passaro says.

"We averaged out the color with the RGB sensor and taught it the face against the background, so as long as some part of the face comes in there, it's going to change the average color enough on the detecting spot to trigger an output," he adds.

LEGO engineers can teach new face combinations by using a teach button on the front of the sensor. "They can control at what point the output will come on versus the return signal from that face," he adds.

The body of the amplifier, the sensor part in the control area, features a teach function. The function uses free-angle optics, an Omron-patented process, which is a series of filters that measures the change in the amount of red, green, and blue light filtered back versus the red, green, and blue light sent out, he adds.

"The engineering makes the process of setting up simple; it's literally the press of a button," Passaro says. "If LEGO is running one line, and needs to change and do different heads on different bodies, it's quick changeover. The engineers teach the new face, adjust the control output, and they run."

Since switching to the sensor, LEGO has had no slowing down of production. "The sensor actually operates faster than the machine needs to go, so there is zero slowing down because of it," Passaro says.

Cyberpage

Direct from www.designnews.com

One of the greatest aspects of the Internet is that information can be updated rapidly. And now the Design News OEM Directory can be found online, updated regularly to include the latest information. Users can search by category, product, or company name. In many cases, email addresses are included to contact the manufacturer directly. To get to the new directory, go to www.designnews.com and click on the button at the top that says "OEM Directory."

Troubleshooting TPEs

Take a TPE guided tour, visit a TPE trouble-shooting section, and review technical data sheets at GLS Corp.'s web site. Also available on the site is information on composite materials, including regulatory and compliance information pertinent to the composites industry. Go to www.glscorp.com.

Hot Spots in Cyberspace -Go with the flow

Computational Fluid Dynamics is an emerging technology and now has its own website, CFD101 at www.flow3d.com. One of the issues addressed is how to grid a flow problem. The site explains the differences between major gridding approaches and shows several methods to get better geometric representations. Also covered is free surface modeling, turbulence in CFD analysis, and the conservation of mass, momentum, and energy.

Calculate with Java

Square D's web site now hosts a motor calculator page that provides real-time information for users specifying motor controls. The calculator is a Java-based tool in which the user can enter the desired horsepower and voltage and review conductors, short circuit protection devices, and motor controls. Check it out at www.squared.com/motodata/calcmotor.html.

You've got the power

If you're in power transmission, you'll have to bookmark the Power Transmission Home Page at www.powertransmission.com. The site features a buyer's guide where users can order price quotes and information from the vendors, feature stories, and industry news.

Strange but true...

Find out who invented the electric chair (a dentist of course!), how many calories are in a stamp, and how old the world's oldest piece of chewing gum is at the "official" strange-but-true web site: http://sbt.bhmedia.com/main.shtml.