Engineering Productivity Kit -- Materials that improve design

DN Staff

September 8, 1997

19 Min Read
Engineering Productivity Kit -- Materials that improve design

Weather no match for these materials

Newton, MA--No one does anything about the weather! Right? Not true when it comes to major resin producers. In fact, several emphasized this point at the recently convened 1997 National Plastics Exposition (NPE '97) in Chicago. Here's a sampling of those weather-beating product announcements:

GE Plastics (Pittsfield, MA) got the ball rolling by introducing a new resin initiative called The WeatherablesTM resins portfolio. Developed in response to a growing demand for lower-maintenance outdoor products with long-term durability, the initiative groups several GE Plastics materials into one well-defined product family:

GELOY(R) ASA (acrylic-styrene-acrylonitrile) resin, commonly used in applications requiring good color property retention after prolonged outdoor exposure.

  • VALOX(R) thermoplastic polyester resin, available in flame-retardant and non-flame-retardant blends and unreinforced and reinforced grades.

  • XENOY(R) resin, which combines the impact resistance and toughness of polycarbonate resin with the chemical resistance and thermal stability of VALOX.

  • LEXAN(R) polycarbonate resin, offering very good transparency, gloss, ultraviolet (UV) light resistance, and impact strength.

The Weatherable portfolio offers increased resistance to light, considerable improvements in weather performance, and the high-quality physical properties of engineering thermoplastic, according to Bob Fines, GE Plastics general manager of marketing. It is targeted for applications in the automotive, electrical, and recreational and maintenance vehicle markets.

"We have state-of-the-art accelerated weathering testing facilities in which we continue to develop new test methods to provide accurate correlation of outdoor performance data," explains Scott Davis, manager of the GE Plastics Weather Lab. "Reliable tests that can predict resin performance are not only important in the development of new products, but also in ensuring the introduction of quality products."

"For the past 18 months GE has focused on creating advanced materials technologies for outdoor vehicle parts," adds Doug Apicella, industry manager for that market segment. One result: the cab of the Emergency-One, Inc. Concept 2000 prototype fire truck.

The cab features body panels thermoformed by Thermoform Plastics, Inc. using MilleniumTM sheet, a three-layer coextrusion from Spartech Plastics. The core layer of the sheet consists of glass-reinforced LEXAN resin, while the outer layers are made of unreinforced LEXAN. Emergency-One selected the material for its light weight, paintability, and durability.

Not to be outdone, BASF Plastics (Mt. Olive, NJ) highlighted its weather-resistant plastics at NPE, exhibiting how the resins meet design needs for unpainted, internally colored plastic applications. The weather-resistant materials include:

Luran(R) S ASA, a high-impact-resistant material for injection molding or extrusion.

  • Ultraform(R) N2320 U017 Red 40516 acetal copolymer, which allows a maximum weathering color shift.

  • Ultramid(R) B3GM35 UV black 23220, a high-strength nylon 6 for unpainted exterior applications.

A new non-polluting electric vehicle for street driving or golf-course use proved a good candidate for Luran S. The patented, lightweight design of the ovoid-shaped, 2-passenger vehicle produced by trans2(R) Corp. (Livonia, MI) features side panels, floor pan, and back body panel made of an ABS polymer base layer and an ASA polymer exterior layer. Able Body Corp. (Joplin, MO) formed the ABS/ASA panels using coextruded sheet from Allen Extruders (Holland, MI) that incorporates Luran S 797 SE UV ASA for its high-impact strength, rigidity, and surface hardness.

Mother Nature also met her match with a new ASA from Bayer Polymers Div. (Pittsburgh) called Centrex(R) 815. "The resin has higher heat and higher glass properties than previous materials," says Silvia Amirin Evans, product management. "It features better weatherability, which results in the excellent appearance of injection-molded parts." Applications include: recreational vehicle antennas, pool accessories, and cable enclosures.

Did you know... 82% of engineers who employ plastic components in their design work process them using injection-molding equipment. 38% use thermoforming, and another 37% rely on extrusion. Nylon (60%) is the preferred material among engineers when it comes to making plastic parts, followed by polycarbonate (54%) and ABS (53%). Source: Design News Market Beat survey

Centrex so impressed CIPA USA that it now uses the new 815 grade to mold its high-gloss mirrors for personal watercraft. "Our mirrors have to pass a 2,000-hr ultraviolet stability program with less than a 1% shift in color," explains Dave Landrith, CIPA vice president and general manager. "Centrex 815 is one of the few materials that will absolutely hold color without turning chalky."

The resin also possesses improved processing properties, says Landrith, including: better knitting characteristics; less gas flow; and the ability to operate in a wider band of moldability. Parts made with the resin do not require the added step of painting, resulting in cost and time savings.

Following suit, Montell Polyolefins (Wilmington, DE) announced at NPE the results of weathering tests on an experimental grade of Hivalloy W polymethyl methacrylate (PMMA) resin. "Due to the acrylic component of the resins, we expected excellent weathering characteristics," reports Ken Dargis, business director, "but the results against ASA indicate Hivalloy W resins may be one of the most weatherable engineering thermoplastics available today."

Specifically, when black samples were irradiated in SAE J1960 testing, Hivalloy W showed a shift in color only one-tenth that of ASA. At the same frequency, the resin retained 93% of its original gloss, compared to 31% for ASA and 0.9% for PC/PBT.

The resin recently got some "real-life" tests in the marine marketplace. Bombardier chose Hivalloy W for the storage hood on the company's newest Sea-Doo(R) watercraft, and Pompanette selected the material for marine deck hatches and bridge chair backs.

Even more recently, ICI Acrylics introduced a "new generation" of acrylic polymers, Lucite(R) AcrithermTM HS, for injection-molded applications that require "optimum weatherability performance, while imparting heat resistance, UV stability, optical clarity, and light transmittance." Tests demonstrate that the polymers "consistently outperform UV-stabilized Pc in resistance to both UV and haze, and allow better light transmission," says Bill Whitaker, polymer market manager.

Two of the HS polymer grades are available: HS3125 designed for parts requiring higher heat resistance than standard acrylic polymers, and KS-5125 for optimum heat tolerance and UV resistance, such as HID metal halide lamps.

Automated system cuts phenolic processing in half

by Dave Roedersheimer Enduron Market Manager Fiberite Inc. Winona, MN

Fiberite's Enduron consists of thermosetting phenolic resin and high-performance fiber. The compression- and transfer-moldable material is available with carbon, aramid, or fiberglass reinforcement. Enduron's high stiffness and inherent strength enable designers to specify wall thicknesses less than 1.0 mm (0.040 inch) for critical space and weight reductions. The material also permits production of complex electronic enclosure shapes requiring cores and slides. However, it was not the easiest material to process. That drawback has now been solved.

Recently, Fiberite partnered with press manufacturer Hull/Finmac Co. to produce an automated system for processing parts made from Enduron. Prior to the introduction of the new system, Enduron had been molded by a labor-intensive process that required hand lay up and hand deflashing. The process was not only slow, it was prone to human error. Hand deflashing, for example, was troublesome and contributed to an undesirable scrap rate. Cycle time was an unacceptable 120 to 140 seconds.

The partnership established a goal of cutting cycle time in half. To achieve this, Fiberite engineers decided to add preheating to the overall process. This would reduce time during the molding part of the cycle. Hull/Finmac engineers concentrated on eliminating manual intervention throughout the cycle by incorporating automation devices into the system.

Ultimately, the new system would have three pick and place mechanisms--one with accuracy to plus or minus 0.005 inch. It would also be equipped with an automated preheater and an automatic modular deflashing unit.

For information on Fiberite's Enduron material phone Dale Brosius, Sales and Marketing Manager, at (810) 220-5770
For information on Hull/Finmac Co.'s Model C150-SMC molding machine phone Jack Mac Innes, Marketing Manager, at (215) 441-8163

Die grinder sets a colorful tone

Houston--For its new 1/3-hp die grinder, INTOOL Inc. wanted a design that stood out from others in the line. The company did it by giving the tool a lightweight composite housing colored with bright neon hues. However, to ensure the housing could withstand the rigors of a typical die-grinding environment, INTOOL engineers settled on a long-glass, fiber-reinforced structural polypropylene.

The material of choice: Verton(R) MFX supplied by LNP Engineering Plastics (Exton, PA). "Verton structural composites gave us the strength and durability we needed," explains Maurice Enderle, INTOOL product manager. "Not only is our CLECO(R) die grinder lighter in weight than conventional cast aluminum models, it also offers excellent abuse resistance. The composite's internal long-glass-fiber matrix is the key to its exceptional toughness."

Verton MFX balances impact resistance and modulus not found in short-fiber-reinforced materials, according to Enderle. It also combines low cost, low specific gravity, toughness, and strength, making it a good replacement candidate for metal.

Another reason for choosing Verton MFX: "It can withstand exposure to a wide variety of lubricants and solvents that a die grinder encounters on the job," says Enderle.

PEEK puts more pizzazz in tubing

Glendale, CA--When it comes to aerospace, military, or commercial applications, protecting wires and fibers becomes critical. That's why Glenair Inc. wanted a material for its convoluted tubing that was not only crunch resistant, but was lightweight and had ultra-low halogen properties.

They found that material in PEEKTM from Victrex USA Inc. (West Chester, PA). "While most tubing materials can provide wire protection, PEEK (polyaryletherketone) polymer is the only material that offers a combination of strength, weight savings, and low outgassing," says Ralph Hays, conduit business unit director. "It's this combination that allows PEEK polymer to outperform other plastics."

The material's use in fiber-optic applications provides a good example. "One reason for using fiber optics is weight reduction, and PEEK polymer is very light in weight and has high tensile strength and crush resistance when compared to PTFE, ETFE, PFA, and FEP. This makes it a perfect encasing for fiber-optic filaments," Hays notes.

Another reason for specifying PEEK: low halogen properties. "This means the material will not emit toxic fumes if there is a fire," Hays explains. "This is a major reason customers specify it for vehicles and other enclosed spaces. We tested the polymer in a Jet Propulsion Laboratory facility and it proved to be a very low outgassing material." PEEK has a V-O flammability rating down to 0.057 inches without the use of additives.

Glenair produces the convoluted tubing in sizes ranging from 3/16 to 2 inches in inside diameter. It comes in a multitude of colors, including natural, black, and red.

Nylon gears quiet power screwdrivers

Towson, MD--Black & Decker produces four types of power screwdrivers that incorporate a planetary gear transmission with two stages, each of which features three nylon gears. The gears run against metal sun gears and an integral ring gear in a zinc transmission housing. But it wasn't always that way.

"When we introduced the first screwdrivers, we used metal gears in the second stage of the transmission," recalls William A. George, engineering manager at Black & Decker. "Now, with gears of Zytel(R) 101L, we get the same durability at lower cost. The gears also run more quietly than metal gears, and their low friction and lubricity makes for smooth operation and wear resistance." Zytel, an unreinforced resin based on nylon 66, is supplied by DuPont Engineering Polymers (Wilmington, DE).

The transmission has an 81:1 ratio to reduce the motor speed to turn the driving head at 180 rpm. Maximum torque on the transmission is 40 inch-lbs (4.5 Nm). The nylon gears each measure 9/16 x 5/32 inch (14.3 mm x 4.0 mm).

The ABA division of ABA-PGT Inc. (Manchester, CT) helped develop the gear design and made the molds. "Zytel provides the consistent properties we need to mold such high-precision gears," stresses ABA-PGT President Samuel Pierson.

Hot runner system injection molds high-temperature thermoplastic

Buffalo Grove, IL--ARUM thermoplastic polyimide resin from Mitsui Toatsu Chemicals (Purchase, NY) is believed to be the most extreme heat-resistant engineering thermoplastic and only polyimide to be conventionally injection molded using hot runner technology. Making this possible is a new externally heated, closed-loop, 5V hot runner system designed by GUNTHER Hot Runner Systems Inc.

When molding 30% carbon-fiber-reinforced AURUM, the hot runner system's nozzle temperatures reach 800 to 815F. These high temperatures are utilized with injection-molding machine temperatures that range from 725F at the rear zone to 770F at the machine nozzle.

HPG Powertrain Systems, a unit of Huron Plastics Group (Pt. Huron, MI) was one of the first companies to successfully injection mold AURUM using the innovative hot runner system technology. "For one particular AURUM component used in an automotive transmission, we reduced the cycle time from 25 to 15 seconds through the use of the 5V system," reports Jay Lockwood, HPG project engineer, "making part cost more attractive for the customer."

The GUNTHER design employs a heating system that requires no heater bands or cartridges. The systems come in 5, 24, or 230V configurations to meet specific applications.

AURUM provides heat resistance to 550F; robust mechanical properties, including tensile strengths to 39,000 psi; wear resistance under high loads and high velocities; resistance to chemicals and automotive fluids; and high purity, according to Mitsui Toatsu Chemicals spokesperson Jennifer Giuliano. The material has been adopted by such companies as United Technologies, GE, 3M, Xerox, and Kodak.

Styrenic makes Happy Meals happier

Terrace, IL--Here's some "food" for thought. In addition to serving 35 million customers around the globe daily, McDonald's Corp. is also the number-one manufacturer of plastic toys in the world.

Simon Marketing Inc., a full-service design engineering and marketing firm, assists McDonald's in developing products such as the ever-popular Happy MealTM toys. "As a supplier to McDonald's, we manufacture millions of the toys a month," says Abdiel Estrella, senior vice president, product development at Simon. "For this reason, we are concerned with the quality of material we use."

To help McDonald's reduce manufacturing costs, Simon began a search for new materials. It found that material in AIMTM advanced styrenic resins from Dow Plastics (Midland, MI) for the toys' housings.

Because of stringent safety standards set by McDonald's, ductile break being a key criterion, ABS (acrylonitrile-butadiene-styrene) had been the material of choice. "However, Dow representatives explained to us that AIM resins exhibit ductile break much like ABS," recalls Walter Kocur, director of research and development at Simon. "After talking with Dow, we understood the kind of performance we could expect from the resins, and that items like the housing could be produced from these materials."

After initial trial production runs, Dow helped Simon overcome technical challenges and optimize the use of the resins for the Happy Meal toys.

Plastic blade gives mower a cutting edge

Newton Aclisse, County Durham, England--A broad range of performance properties offered by a single polymer has enabled Electrolux Outdoor Products U.K Ltd., a major garden-tool maker, to launch a "revolutionary" Flymo rotary lawn mower with a plastic blade.

Flymo experimented for some time with the production of a non-metal blade for its mowers. Plastics offered potential advantages of lighter weight, as well as being less expensive and rust-proof. In addition, plastic blades would enable a lighter motor to be used, reducing the overall weight of the mower.

Blades made from traditional plastics tend to wear easily, however, and, although relatively inexpensive to purchase, Flymo found customers had to replace the blades frequently. The solution: aliphatic polyketone CARILON Polymers from Shell Chemical Co. (Houston).

By contrast, CARILON Polymers offer good friction and wear characteristics, high resistance to water and chemicals, and they process easily, with the added benefit of good mold definition. Encouraged by this, Flymo molded a number of prototype blades from the polymer. In comparative tests with blades made from Flymo's existing polymer, a modified acetal, the CARILON blade lasted an average of 10 times longer. Flymo subsequently reproduced these results in the field.

As a result, Flymo developed a CARILON blade for its new MC30 rotary mower. Impressed by this initial success, Flymo also used the polymer as the material for a new type of blade in their popular edge-trimming tool, the Minitrim Trimmer. Now, the mower and the trimmer sport the new, durable plastic blades that give both products a distinct performance advantage.

Plastic gives snowboard binding a competitive edge

Sun Valley, CA--Aastro Molds Inc. has introduced a snowboard binding aptly named Price BreakTM. The single-piece binding provides users with the high-performance characteristics of expensive bindings, but at a price comparable with bindings at the lower end of the market.

"We were using an impact-modified, super-tough nylon for this product," says Randy Smith, plant manager for Aastro. "However, that material was a little bit soft. The snowboard riders who used the previous binding were experiencing some toe and heel lift when they performed trick maneuvers, and that's not acceptable."

Smith talked with Amoco Polymers (Alphretta, GA) about using a stiffer material that wouldn't "cost an arm and a leg." They suggested AMODEL(R) polyphthalamide (PPA) not only because of its performance properties, but also for its appearance. "Glass-filled materials don't usually have good surface appearance, but AMODEL does," Smith adds.

Changing to the new material required some mold modifications. "Our first test didn't work out well because the mold was designed for nylon, and AMODEL flowed differently," Smith explains. "We changed our gating system and the vent locations, and the result was a product that passed all our in-house tests."

Aastro sent 25 pairs of bindings into the field for testing; two of them developed hairline cracks. So the company redesigned the binding by changing some of the radii, with no problems in subsequent tests.

"This new Price Break binding design is our attempt to satisfy snowboard riders' needs for performance and economy," says Smith. "Inexpensive snowboard bindings are notorious for problems, but riders buy them anyway, because they like the price. Our binding is competitively priced, but offers excellent performance."

Productivity Kit: Materials that improve design

Soft magnetic alloy

Carpenter Technology Corp. has developed a new soft magnetic alloy, Chrome Core(R) 18-FM stainless, with more corrosion resistance than 18% Cr Type 430 stainless and with similar magnetic properties. The material is designed for use with fuels containing ethanol or methanol and the contaminants associated with these fuels. It is offered as a candidate for automotive applications, such as fuel injection, antilock braking systems, and automatically adjusting suspension systems, as well as for solenoid valves, pumps, fittings, and other parts for the appliance industry. In the magnetically soft condition, the alloy requires only machining for production of solenoid parts.

Semiconductor polyimide

EGC Corp. has introduced a material designed specifically for the semiconductor industry. Called Xytrex(R) 574 HP, the polyimide can withstand abrasion without requiring additives that could contaminate the process environment. The material resists temperatures up to 550F (288C), while maintaining tensile strength (20,000 psi), flexural modulus (550,000 psi), and compressive strength (34,800 psi).

Modeling paste

Monolite, a monocomponent epoxy modeling paste from Axson, rapidly creates or modifies models, mock-ups, and prototype designs. The single epoxy-based component requires no mixing equipment. Supplied in frozen form and available in a range of hardnesses, the non-toxic materials can be applied over a rough model, subform, or armature, then vacuum-cured at low temperature in an oven before final tooling.

Mold-grade aluminum

A. Finkl & Sons Co. has introduced Alu-XTM Premium Forged Aluminum, "the first fully forged and thermal-treated aluminum designed to provide superior results in a variety of plastics applications." The aluminum provides thermal conductivity 12% better than 7075-T651 commonly used in mold applications, claims the company, as well as superior hardness and surface strength at working temperatures. The material is fully forged to a minimum 4-to-1 reduction to provide a structure free of micro-voids and porosity. Thermal stabilization minimizes distortion encountered when machining.

Insulation protection

Bentley-Harris Inc. has introduced THERMFLEX(R) 1250, a high-temperature sleeving designed to provide improved insulation protection when installed on Exhaust Gas Recirculation (EGR) tubes. The sleeving is recommended for use in environments where EGR gas inlet temperatures reach up to 1,800F. Made entirely of fiberglass, the material incorporates four knitted cords integrally braided into the corner of the sleeve. The inner cords create a partitioned insulating air gap to enhance the sleeve's effectiveness.

Powder metal potpourri

Catalog describes current and new publications published or distributed by the Metal Powder Industries Federation. Listed are proceedings of international conferences and technical meetings, text books, manuals, lectures, standards, educational videos, and new electronic products. Publications cover advances in particulate materials, cutting tools, ferrous powder metallurgy, cemented carbides, metal and ceramic injection molding, tungsten and refractory metals, high-temperature behavior of ceramic composites, sintering theory and practice, sintered machine elements, liquid phase sintering, and handling of powders and dusts.

Sign up for the Design News Daily newsletter.

You May Also Like