Coming down the line: five emerging technologies for automotive.
Commercialization of promising "cutting-edge" technologies for manufacturing automotive components, with all their potential for high-volume business opportunities, could be critical to survival domestic processors facing strong global competition. For molders in other sectors, automotive commercialization could represent a crucible in which the manufacturing economics of these processes - some quite new, and others still on the early part of their growth curve - will be refined and clarified to a degree that will benefit many other markets.
Advanced structural thermoset and thermoplastic composites, large-part blow molding, and gas-assisted and lost-core injection molding techniques are the emerging automotive processing methods that have gripped the attention of materials and machinery suppliers, as well as car makers, in the last few years. But is anyone in North America actually making car parts using these methods?
On the following pages, our editors have compiled a status report on both the commercial and technical viability of these five processes. The thrust is to identify those involved in vanguard development efforts here in North America and to chart the progress of the process in terms of real-world manufacturing programs.
The two liquid composite molding (LCM) technologies of structural reaction injection molding (SRIM) and resin transfer molding (RTM), having achieved the capability to automate the glass-preform process, are now embarking on new applications and finally beginning to demonstrate their full commercial viability for structural automotive components. Thermoplastic composites, both compression molded sheet and reinforced injection molded parts, continue to penetrate automotive niches, highlighted by a fully commercial, high-speed automated system for producing bumper beams.
Large-part, 3-D blow molding technologies are still mainly in the development phase, despite some commercial applications. But proponents are establishing ambitious near-term goals, with research work now under way to deliver a blow molded dashboard for a 1995 vehicle platform.
Gas-assisted injection molding, a 10-year-old process in which gas is injected into a mold along with resin to create hollow sections; and lost-core molding, a relatively new process based on a centuries-old idea in which a core is encapsulated with plastic and then melted away, are both finally coming of age in U.S. automotive molding.
The holdup for gas injection, which is said to bring many structural and cost improvements to interior and exterior trim parts, is ongoing threats of patent litigation. The holdup for automotive lost-core molding, which has no patent or license restrictions, is the six to eight years of development time required for applications big enough to justify the extremely high capital investment.
Liquid Composite Molding
Precise automated production of glass preforms, improved tool and part designs that reduce scrap, and faster-curing resin chemistries are making structural reaction injection molding (SRIM) technology a viable option for high-volume manufacturing of structural automotive parts.
One of two liquid composite molding (LCM) methods, SRIM technology is now being used for high-volume production of bumper beams, with additional applications such as cross-car beams under development. The other LCM technology - resin transfer molding (RTM) - is also heading for full commercialization, but for lower-volume (3000 to 20,000 units) auto and truck applications such as on the new Viper sports car from Chrysler Corp. Only some of the RTM applications, such as the underbody pan for the Viper, may be considered structural, while others are more decorative (i.e., exterior body panels).
In addition to new commercial programs by individual firms, major technology objectives for LCM techniques are being achieved through the cooperative development efforts of Detroit's Big Three via the Automotive Composites Consortium.
CONSORTIUM REACHING GOALS
Substantial progress in advancing automotive structural composites - especially via LCM - is being made by the Automotive Composites Consortium (ACC), Troy, Mich., the technology group formed by Ford Motor Co., General Motors Corp., and Chrysler Corp. in August 1988 (see PT, July '88, p. 94; Sept. '89, p. 108).
When interviewed by PLASTICS TECHNOLOGY two years ago, ACC officials listed these four areas as being among the key initial goals of the program: development more rapid, automated fabrication of preforms to meet automotive production rates; creating a synergy between design, processing, and assembly phases of operations; development of a standardized "test plaque" and related software program for statistical analysis of mechanical data such as creep, fatigue, impact stress and environmental durability; and obtaining quantitative data on part performance during actual 30-mph crash tests. The group now reports all of these goals have been achieved.
By forming a research partnership with the National Institute of Standards & Technology (PT, May '91, p. 29), and bringing together design and manufacturing engineering data, the ACC recently was able to compile a formal test manual, establishing standards for test methods and mechanical performance of composites.
The ACC also is putting together a standard engineering database for part suppliers by developing a composite test plaque and tool, and related software programs. The consortium now can provide composite parts vendors with a floppy disk that can format and analyze statistical test data, based on the performance of the 24 x 24 in. test plaque. This should give automotive designers and engineers greater confidence in the reproducibility of test and quality information.
Elio Eusebi, ACC chairman and director of the Polymers Department at the GM research center in Warren, Mich., says testing and development work for the group continues on front-end vehicle rails, produced by RTM, as test bed to demonstrate technological capabilities of the process (see Pt, Sept. '89, p. 111). (Front-end rails are the structural members located beneath a car's fenders that support the engine and manage the energy absorbed in a frontal collision.)
Production of the composite front rails for an actual commercial automotive platform would have been impossible to consider just two years ago, given the time required to assemble the glass preform according to Eusebi. Now, by automating the process, preforms can be assembled in minutes, approaching the rates required for high-volume automotive production, he says. Vinyl ester currently is the matrix resin employed by the consortium in the LCM process for producing composite front rails, although other resin systems will be sampled in the future, Eusebi says.
While RTM research on front rails continues as an important program for the consortium, Eusebi says the group has even greater interest in developing SRIM for commercial applications. Last year, the ACC entered into agreements with six molders and materials suppliers to conduct joint studies on SRIM and RTM (PT, Oct. '90, p. 94).
The consortium also is involved in a development effort to fabricate a structural cross member through the SRIM process. (A cross member is a front-end component that supports the transmission and is tied the vehicle's suspension system). As in the RTM effort, automating the fabrication process for SRIM glass preforms is a key development focus.
Manufacturing technology supplied by Admiral Equipment Co., Akron, Ohio, for the automated production of SRIM glass preforms is currently being used for high-volume production of structural composite front and rear bumper beams. Admiral's parent firm, Dow Chemical Co., Midland, Mich., identifies General Motors Corp.'s Buick Roadmaster sedan and station wagon as the platform utilizing the SRIM technology.
Admiral executives say production will be above 100,000 parts for 1992, and is slated to exceed 300,000 parts by the 1993 model year. Production of glass preforms as well as molding bumper beams will be performed as a captive operation at the RIMIR facility in Matamoros, Mexico, of GM's Inland Fisher Guide Div. Dow's Spectrim MM310 polycarbamate urethane is the resin being used in the system. The bumpers are designed to withstand 5-mph impacts and represent a 40% weight savings over the same design in steel.
The essential technical challenge of the SRIM bumper beam is automated production of the glass-mat preform, according to M.K. (Ken) Mitchell, Admiral president and general manager. Admiral's modular, automated system, driven by programmable logic controllers (PLCs), can fabricate preforms using up to eight different layers of glass. Depending on part specifications, the system can incorporate various orientations of glass reinforcement (unindirectional, random fibers, woven mat, etc.) into a single glass charge.
The multiple glass layers are unwound and joined in laminate form and automatically forwarded to a sheeter and preheating oven, where the mat is cut to size. The glass has a thermoplastic binder, which accounts for about 7% of total preform weight. The pre-heated charge, weighing up to 14 lb, is placed in a press, where the glass is formed, cut and cooled. Part-to-part cycle time between oven and press to form the glass charge is about 90 sec. For molding the finished bumper beam, the SRIM system makes use of a low-viscosity polyurethane matrix resin. Each bumper beam has a total molding cycle time of about 3 min.
Admiral says target goals for this process are to produce glass preforms in under 1 min, and bring the resin molding process to under 2 min. These reduced cycle-time goals already are achievable on a limited, short-term basis, given optimum processing conditions, Admiral says.
Tary L. Schumacher, director of marketing, explains that PLCs in the automated preforming system give processors the ability to program exact length, configuration and shape of the charge to be used as a bumper beam. This control capability makes it possible to drive down scrap or "offal" rates as low as 10%, compared with typical scrap rates of nearly 50% in manual preform operations. "A typical SRIM process requires a high volume of excess glass on the preform," he says. "Our process allows engineers to reduce scrap through accurate part design. We can form the glass charge very close to the exact part size." He says the tool used in forming the glass charge has slide cores and other proprietary features that can form the closer to the cut edge of the actual part.
Besides its work on automating and quickening the preform cycle, Admiral also is developing equipment and processes to handle faster-curing SRIM systems in conjunction with Dow. The test bed for this effort is a vertical 1000-ton RIM press located at Admiral's facilities in Freeport, Texas. Research developments on this machine include a shuttling bottom platen that permits tool-change flexibility; capability for pumping up to 40 lb/sec; and utilization of Dow's patented "cut-and-shoot" technology, where a RIM part is both molded and trimmed in the same tool (PT, March '91, p. 49).
SRIM CROSS-MEMBER BEAMS
SRIM research work for the Automotive Materials Group of Dow Plastics includes developmental programs for structural cross-car beams and instrument-panel carriers. This R&D work could potentially result in components on 1995 or 1996 vehicles. (Cross-car beams are bolted to a vehicle's A-Pillar, resting behind the front cowl. The instrument panel carrier is the structural under-skeleton of the IP, which in turn hangs on the cross-car beam.)
The benefits of parts consolidation, built-in functionality, and weight reduction are the main drivers in this SRIM effort, according to Dick Giba, Dow's advanced marketing manager for interior systems. Giba reports Dow is currently involved in several joint development programs with automotive OEMs and tier-one level custom processors. Dow's automotive development center in Southfield, Mich., is the site spearheading the research.
As is the case with structural bumper beams, a major focus of the development efforts for cross-car beams and instrument-panel carriers is automating and refining the glass-preform process. Development of these two structural components is distinct from work being carried out at Dow's Admiral subsidiary. Urethane resin systems are also being used in these programs.
NEW VIPER HIGHLIGHTS RTM
Production on Chrysler Corp.'s new Viper, a low-volume, specialty sports vehicle that will feature body panels and various structural components fabricated via the RTM process, is slated to begin in mid-1992. The RTM components will be attached to a steel space frame. The initial volume is expected to be 3000 vehicles.
Aero Manufacturing, div. of Aero Detroit Inc. in Sterling Heights, Mich.; Rockwell International, Troy, Mich.; and ETM Enterprises Inc., Grand Ledge, Mich., will be tier-one custom processors for the components on the Viper platform. The RTM process will utilize a calcium carbonate-filled thermoset acrylic - Modar 824LTS from ICI Acrylics/K-S-H Inc., St. Louis.
A spokesman for ICI Acrylics says the development effort for the Viper program features close cooperation between Chrysler, the custom molders, and ICI. The process will feature an automated glass-preform system. The preform glass rolls will be supplied by Vetrotex Certain Teed Corp.; Maumee, Ohio. The Modar acrylic will be injected into heated molds.
Key to the successful implementation of the Viper process technology will be the rapid cure of the acrylic RTM parts. An ICI spokesman says parts typically will be demolded at the peak of exotherm, reportedly achieving high green strength and a Barcol Hardness rating of 45 within 10 min after demolding. Compared with traditional polyester RTM chemistry, the acrylic resin system will provide lower shrinkage and higher dimensional stability, greater strength and stiffness, resistance to cracking in resin-rich areas, higher gloss and smoother finish, according to ICI.
RTM TRUCK HOOD ASSEMBLY
Executive of Rockwell International say they are now in the launch phase for the production of a new RTM hood assembly for Ford Class 8 tractor trailers. Because of the relatively low annual volume of the application - under 10,000 units - the cost/performance of RTM tooling, compared with SRIM or SMC, is a decisive factor, according to Nate Ustick, technical director for Rockwell Plastic Products, and Ajay Kharod, materials engineer.
The new program for Ford will encompass 12 components forming both the outer and inner structure of the hood. A polyester resin system will be used for the process, which has only limited automation in secondary bonding/assembly operations and some automation in the glass reinforcement preforming. It was learned the automated glass-preform fabrication system was supplied to Rockwell by Cannon U.S.A., Mars, Pa.
ICI Acrylics will also supply Modar 824LTS thermoset acrylic resin for production of new one-piece RTM tractor-trailer hoods for Kenworth T600 and Mark RD trucks. Rene Fiberglass, Saint Ephrem, Quebec, will fabricate the glass preforms and mold the parts.
Structural Thermoplastic Composites
Compression and injection molding of structural thermoplastic composites continue to find application im bumper beams, load floors, seats and knee bolsters, and some smaller structural parts. All indications are that TP composites will be limited mainly to existing commercial applications for the near term.
However, this could change with the advent of more automated molding systems and more versatile materials utilizing., chopped and unidirectional glass reinforcements, improved sizing chemistries, and higher-performance engineering resins. Improved coupling and long-glass fibers are also making injection molding more competitive with sheet stamping.
AUTOMATED SHEET STAMPING
High-speed, computerized and automated compression molding of glass mat/TP composite front and rear bumper beams for GM's 1992 Buick LeSabre may represent a breackthrough in productive for thermoplastic composites that could helpp them break new ground in automotive. As previously reported in PLASTICS TECHNOLOGY, Wickes Manufacturing Co. in Grand Rapids, Mich., is the first-tier manufacturer of the bumper beam.
Production is ramping up on a single, fully automated stamping line, which includes a proprietary process for bonding the compression molded glass-mat TP sheet to a preformed nickle/chrome-plated stainless-steel cladding (PT, Dec. '90, p. 31; Sept. '89, p. 95). The system is totally automated from oven loading through programmed charge stacking, press loading, molding, parts removal, cooling, trimming, routing and drilling.
Wickes executives say only that cycle times run in excess of 1 min, declining to elaborate further on the operation. Although this is the first system of its type in North America, four fully automated thermoplastic sheet-stamping lines are in operation at Volkswagen AG im Wolfsburg, Germany, supplied by Hoesch MFD, which recently was acquired by Deiffenbacher of Germany (represented here by Marvel Equipment Corp., Farmington Hills, Mich.). Those lines are said to operate on 30-sec cycles.
Annual volumes for the Buick bumper beam are slated to be about 200,000 units, according to Wickes executives. The beams, believed to weigh 15-20 lb each, are designed to wiethstand 5-mph impacts. Finished parts are shipped to GM's Buick installations in Flint, Mich., for final assembly.
TRENDS IN SHEET MATERIALS
Several recent developments in reinforced thermoplastic sheet stamping materials are opening up new applications potential. One is the use of resins other than PP. GE Plastics, Pittsfield, Mass., has commercialized Azloy polycarbonate/ PBT alloy-based sheet for rocker-panel reinforcements on the BMW Z-1 roadster,a nd Azmet PET-based sheet for higher temperature uses such as engine and exhaust heat shields on two Porsche Carrera models (PT, May '91, p. 179).
Another is the use of unidirectional glass fibers in the sheet material. This was true of the Azmet applications noted above; and the Plastics Products unit (formerly Butler Polymet) of Rockwell International, Troy, Mich., combines a layer of unidirectional Azdel PP sheet with standard random-fiber glass mat in molding front and rear bumper beams for the Honda Accord.
Both GE Plastics and Exxon Chemical Co.'s automotive group in Farmington Hills, Mich., believe more complex structural shapes will require the improved flowability of chopped-fiber composite sheet in place of the traditional continuous-strand mat. Both firms also have introduced new coupling agents into their PP/glass formulations to achieve 10-25% improvements in mechanical properties at the same glass loading (see PT, April '91, p. 31).
New coupling agents are making lower cost polyolefins competitive with more expensive engineering resins in conventional short-glass injection molding compounds. Earlier this year, Himont Advanced Materials, Lansing, Mich., brought out HiGlass BJ44AC, a high-flow, impact-modified PP with 10-50% coupled glass (see PT, April '91, p. 31).
Dan Kult, Himont market development manager for automotive exteriors, says this new material is being injection molded by coptive operations of unnamed auto builders for two structural applications. One is a headlamp retainer, which this year appeared on three car models. The second and more developmental applications involves internal structural door members, slated to be launched on a vehicle platform in the second quarter of next year.
The injection molded headlamp retainer spans the full which of the car. Kult says the part was previously molded in glass-filled PBT. By changing to PP, Kult says part weight was reduced by 25%, cycle time was reduced by 17% (from 48 to 40 sec), and processing temperature was lowered by 70 [degrees] F to 430 F. In addition, lower injection pressures help to reduce tool wear and flashing, he adds. Existing tooling for the part was maintained.
A newer development now being finalized, which makes uses of a modified version of HiGlass BJ44AC, will replace metal parts on internal structural door members. This application, also proprietary, will be launched on a 1992 mid-year model car.
The Engineering Thermoplastics Div. of Hoechst Celanese Corp., Chatham, N.J., announced earlier this year that 40% long-fiber reinforced Celstran PP/glass injections molding compounds with new coupling technology can compete in mechanical properties with stamped sheet, and even thermoset composites (PT, April '91, p. 31).
Large-Part & 3-D Blow Molding
New development efforts that target more complex future applications, especially instrument panels and fascias, represent technology challenges for large-part/3-D blow molding. Improving processing equipment and tooling to deal with large parisons, ensuring part-to-part consistency and uniform wall thickness, and reducing scrap are goals now being addressed.
Even with successful blow molded tractor-trailer skirts and fairings and passenger-car bumpers to show the way, ambitious expectations for larger-part $ 3-D blow molding in automotive applications during the late 1980s proved to be premature, and have since given way to a more conservative outlook (see PT, Oct. '87, p. 99; May '89, p. 54). Blow molding capacity among captive and custom automotive processors remains relatively small. Ford Motor Co. is believed to be the only North American car maker with any significant captive blow molding capacity.
Demonstrating the capability to design and build more sophisticated tooling - incorporating attachment points and complex shapes while limiting high rates of flash and regrind - is a crucial challenge for blow molding if it is to attract more ambitious automotive applications. Current surface-quality drawbacks limit blow molded components mainly to nonappearance applications. Despite these considerations, the lure of blow molding continues to be relatively low tooling costs, parts consilidation, and rapid cycle times.
INSTRUMENT PANELS BECKON
Research is now under way at ABC Group in Rexdale, Ontario, on behalf of one Big Three auto maker seeking to develop a blow moded instrument panel for a 1995 vehicle. Frank Dabkowski, senior project engineer, and Tom Roley, sales and engineering manger for the International Sales & Engineering Inc. unit of ABC Group in Southfield, Mich., say the unnamed car maker recently approved ABC's tool design for the blow molded IP. They say ABC soon will begin cutting the initial tool for the part in order to mold prototypes for further evaluation.
At least unfilled resin systems, including nylon, are being considered for the program. ABC currently is blow molding IPs for Mack Trucks, Inc., Allentown, Pa., using a less complex design than the one for new developmental auto application (PT, July '89, p. 89).
ABC Group is also producing blow molded rear seat backs for the GM Chevrolet Corsica/Beretta platform, and will process a seat panel for the 1993 Chevrolet Blazer. Both applications will use Marlex ER9-0020 25% mica-filled HDPE from Phillips 66 Co., Pasadena, Texas.
The Automotive Materials Group of Dow Plastics, Midland, Mich., is involved in several large-part blow molding development programs - primarily in IPs - with automotive OEMs and first-tier suppliers, targeting 1995 car platforms. One early harvest of these efforts is a blow molded IP cluster cover, which will appear on a 1992 GM platform. An unfilled blow molding grade of Dow's Pulse 880 BG ABS/PC is the material of choice. Part design and tooling are the major challenges in this effort; in particular, development work is geared towards molding-in bosses and attachment points on the complex parts, as well as engineering consistent wall thickness throughout the component.
Kenneth C. Enneking, assistant product manager for instrument panels and interior-trim development for GM's Warren, Mich.-based Inland Fisher Guide unit, confirms that the blow molded cluster shroud, an appearance part that houses the speedometer and other gauges, will be used ont he 1992 Pontiac N car. The component will include an integral, molded-in air duct and will be vacuum cladded with a vinyl skin for better feel and surface appearance, he says.
3-D BLOW MOLDING
Three dimensional blow molding of engineering materials into complex shapes for automotive will be the subject of research at the new Cincinnati Development Center of the Engineering Plastics Div. of Hoechst Celanese Corp. (see PT, Dec, '90, p. 76). Michael McGill, manager of advanced processing technology systems, says that Cincinnati Center will receive this month a modified 3-D blow molder from Placo Co. Ltd. of Japan (U.S. offices in Torrance, Calif.) with a multilayer head.
The Placo machine is one of two designs from Japan (the other proprietary to custom molder Excell Corp. and its MES subsidiary in the U.S.) that extrudes a parison into a titled or horizontal mold cavity, in order to produce complex 3-D shapes such as snaky-looking ducts with little or no flash (PT, March '87, p. 67; May '89, p. 58).
The 65-ton Placo machine for the Hoechst Celanese center features a movable x-ray mold table under a fixed, multilayer, 6-lb extrusion head. Through CNC control, a parison is dispensed continuously technology has a moving x-y extrusion head and a fixed table).
McGill acknowledges 3-D blow molding is relatively new to North America, with most applications development work still in Japan. But the 3-D method has the potential to greatly reduce levels of scrap and regrind, as the programmed placement of the parison enables parts to be "assembled" in a mold cavity. The geometry of parison placement can be controlled, either by movement of the mold fixture or extrusion head. The process also allows for precise control of wall thickness.
The concept of "one-step manufacturing" - obtaining a finished blow molded part straight out of the mold, including integral features like air ducts, flexible bellows, encapsulated inserts and connection points - will be a driving force behind the Hoechst Celanese development effort, according to McGill. Coextrusion capabilities of the machine will allow simultaneous molding of rigid and flexible layers of material.
While he cites no specific research program or OEM partnership, McGill says applications development at the Center will concentrate on complex-geometry, under-hood tubular parts, manifolds, bumpers, side moldings, and fuel-intake pipes. The Placo machine will be specially modified to process higher-temperature engineering thermoplastics (700 F range) such as PPS, liquid-crystal polymers, acetal, nylon and polyesters.
Despite its potential, the 3-D blow molding process must still address several questions, according to McGill. First, the process thus far has had slower cycles than traditional blow molding. Second, cosmetic irregularities (gels, die lines) and overall surface quality may limit it to nonappearance applications. Third, for larger parts such as bumpers or instrument panels, the 3-D technology could be limited to certain resins that can lay against a mold surface for the duration of the parison-placement operation without freezing off (crystallizing) before the part is fully dispensed and formed. Finally, control and reduction of scrap/regrind levels must be fully demonstrated in order to attain the cost/performance requirements for automotive molding.
As reported last year, GM's Inland Fisher Guide unit continues to test and review a variety of prototype 3-D blow molded interior trim, bumpers and exterior claddings, fabricated by MES Corp., Troy, Mich. (see PT, Sept. '90, p. 79; Aug. '90, p. 65). Enneking of Inland Fisher Guide says the proprietary MES process, which also features horizontal placement of the extruded parison into the cavity, minimizes parison stretching and wall-thickness variation. The horizontal geometry also permits the use of a wide assortment engineering thermoplastics that would not normally have sufficient melt strength to support a parison for a component as large as an instrument panel or spoiler.
Gas Injection Molding
Gas-assisted injection molding is a 10-year-old process in which gas is injected into a mold along with resin to create hollow sections in a part. Despite fuzzy patent ownership for the technology, Big Three auto companies all have gas-assist parts either in production or under evaluation - some in house, some with custom molders.
General Motors Corp., for example, in July got a new three-cylinder gas-assist unit from U.K. based Cinpres Ltd. for its Inland Fisher Guide div., Troy, Mich. GM also has Airmould gas-assist from Battenfeld of American, West Warwick, R.I., on a Battenfeld coinjection machine and works with Advanced CAE Technology Inc., Ithaca, N.Y., on mold-filling simulations of interior and exterior trim (see PT, Feb. '91, p. 14). Gas-assist development programs include bumper fascia and multi-component seating units.
GM also uses gas-injected parts from custom molder Cascade Engineering Inc., Grand Rapids, Mich. (a Cinpres licensee), including interior panel assemblies, flat rectangular headlight trim, and in-mold-carpeted instrument panel fillers for a van. "We've got a lot of automotive projects on the drawing boards with Cinpres," says Cascade's engineer for gas injection Noland Broadus. Cascade also gas-injection molds a rear exterior panel and bumper fascia for a U.S.-assembled foreign car.
Chrysler Corp., an early advocate of gas injection, gets over 2 million gas-assist parts annually for its S-body minivan from custom molder Automotive Plastic Technologies (APT), Sterling Heights, Mich. (formerly Detroit Plastic Molding Co.). These include the largest U.S. gas-assist part: a quarter-panel with cup holder, consolidating 12 separate parts.
Ford Motor Co. leases gas-assist R&D equipment from GAIN Technologies Inc., Mt. Clemens, Mich., but has no license or gas-injection parts officially in production. Ford's plastic-trim part development group is considering gas injection molding for door panels, spoilers, and bumpers. "By modifying some tools no longer in production and conducting engineering studies, we hope to be able to understand the process for ourselves and the limitations of each of three methods [GAIN, Cinpres, Battenfeld Airmould]. It could take a year before we decide," says Kenneth Bladzik, Ford Motor Co.'s manager of process development and technology planning. (Some custom molders says Ford in fact uses some gas-assist parts that come from "second-tier" suppliers, but may not be aware of it.)
With so many gas-assist applications coming along, materials companies are buying equipment to learn more about the process. GE Plastics, Pittsfield, Mass., has a four-cylinder Cinpres unit. ICI Advanced Materials, Exton, Pa., has a development license from Cinpres (PT, Nov. '89, p. 86). And automotive compounder D&S Plastics International (formerly Dexter Plastics), Troy, Mich., is buying Battenfeld coinjection with Airmould gas-assist equipment and a Cinpres hold-harmless license for a new automotive R&D center in Auburn Hills, Mich. (PT, April '91, p. 127).
A COMPETITIVE EDGE
Sometimes gas injection means the difference between success and failure in a part. When Lacks Industries in Grand Rapids, Mich., tried to mold solid ABS bumper fascias 60 in. long x 3 in. wide and 1/8-in. thick with a fat upper edge, the parts curled. The problem was solved when a subcontractor used gas to channel the upper edge.
Gas, which takes the path of least resistance in the mold, can make problems too. As little as 0.001-in. differences in diameter or a melt channel between mold halves will send more gas one way.
"You may also find gas permeating areas outside of the gas channel. You get several good parts and one with |wandering gas,' where gas shows up as an internal blister in a solid wall area. Present knowledge of the process doesn't allow design of a mold for gas that works the first time," Ford's Bladzik says. Processors say molds often go back and forth to the shop many times for corrections.
Trial and error may be reduced in future by using new flow-simulation computer programs to model gas injection, from Advanced CAE Technology (noted above); Moldflow Inc., Trumbull, Conn. (PT, Feb. '91, p. 14); and Plastics & Computer Inc., Montclair, N.J. (PT, Aug. '91, p. 78).
Designs that inherently won't work with gas-assist include "parts with a lot of return walls where you're running plastic down a wall or down the cavity with a lot of variable wall thickness," says Cascade's Broaddus.
PATENT DOUBTS PERSIST
"We're cautious in implementing gas-assist because of litigation," Ford's Bladzik says, referring to years of lawsuits and threats of suits among GAIN, Cinpres, several molders, and equipment suppliers.
Ford isn't alone in being cautious. Two years ago, when PLASTICS TECHNOLOGY devoted a feature to high hopes for gas injection (PT, June '89, p. 70), three companies in the U.S. were known to practice it. Detroit Plastic Molding Co. (now APT) licensed technology from sisterm firm GAIN; Cascade licensed from Cinpres; and Sajar Plastics Inc., Middlefield, Ohio, from sister firm Nitrojection Corp. in Middlefield. Encore Systems Inc., East Detroit, Mich., sold gas-assist systems without license, and European injection machine builders offered equipment systems but kept low profiles in the litigious. U.S. Three years later, only a handful more molders admit to using gas assist. (For more on patent issues, see PT, June '89, p. 70; Jan. '90, p. 98; Aug. '90, p. 14; Oct. '90, p. 37, Feb. '91, p. 14; and July '91, p. 44).
As it stands now, GAIN and Cinpres appear to have reached a truce. Battenfeld, Engel Canada Inc. of Guelph, Ontario, and Klockner Ferromatik Desma of Germany (represented here by KFD Sales & Service Inc., Erlanger, Ky.) have agreements with Cinpres. KFD general manager Robert Hare says Klockner provides gas-assist equipment in Europe with a Cinpres license, but "in the U.S. everybody's still leery."
GAIN won a $2.5-million judgment in April personally against Sajar R&D head Indra Baxi. But Nitrojection, whose technology Sajar uses, claims to be in the clear. "There's been no legal challenge to Nitrojection's process, just threats, but it's amazing how threats held American industry up," says Nitrojection CEO Thomas Johnson. Nitrojection, whose technology simultaneously injects gas and melt at nozzle or cavity, says it has more than four U.S. licensees.
APT, which licenses GAIN and Nitrojection technology, also offers its own Gastech system. Pending Gastech patents for special gas-injection pins, "zero-carriage-motion" gas-injection nozzles designed to function without sprue break (covered by GAIN patents), gasmetering controls, and tooling "are judged not to infringe any of the existing commercial systems of patents," says APT v.p./GM accounts Bruce Schafer. Gastech hardware and know-how costs $20,000-40,000 without ongoing fees. GM's Saturn Corp. is said to be currently reviewing Gastech.
Recently, GAIN and Cinpres began issuing patent-only, "hold-harmless agreements" that forestall litigation but involve no transfer of equipment or technology. GAIN sold its first to Daimler-Benz of Germany to allow U.S. import of roadsters with gas-injected parts. Cinpres offers patent-only licenses to users of Battenfeld's Airmould, Engel's Gasmelt, and Klockner's Airpress systems. GAIN and Cinpres also recently lowered fees.
GAS-ASSIST MOLDERS PROLIFERATE
Beginning in February, after a GAIN/Cinpres legal truce, both companies signed up new automotive molders. These include five for Cinpres: GM, GE, and Worthington Custom Plastics (formerly Millington Plastics), Sandusky, Ohio, Cinpres says six more licensees will be signed soon, five of them automotive molders.
Since February, GAIN signed up AMP Industries Div. of American Model and Pattern Inc., Mt. Clemens, Mich., and Venture Plastics Industries, Frazier, Mich., and says it will have three more licensees by fall. GAIN also has a technology development agreement with AMP, which has had gas-assist auto parts in production six months. AMP v.p. Karl V. Blankeburg says. "We're creating some really amazing things by integrating gas-assist with our patented Engineered Geometric Design," which incorporates interlocking geometric structures for rigidity and strength, like corrugation in paperboard. AMP is using gas channels to make these corrugations and working with GM on seating units, Ford on spoilers, and Chrysler on bumpers.
In addition, Prince Corp., Holland, Mich., is ordering Battenfeld's Airmould. And American Bictech Inc., Erwin, Tenn., ordered an Engel coinjection press with Gasmelt for R&D work (reportedly for Ford and Saturn) and is considering GAIN or Cinpres licenses. Bictech v.p. Rob Stromberg says the choice "depends almost totally on what the part looks like. If you only want gas in a portion of the part, you're better with Cinpres. If you want gas all over, that's probably GAIN."
A new gas-assist process is a patent-pending "hot-liquid" system from Hettinga Equipment Inc., Des Moines, Iowa, on the market 1.5 years and seen at NPE (see PT, Aug. '91, p. 36). Hettinga charges a one-time $75,000 license fee, no royalty, and sells the system with its own low-pressure injection machine or retrofits non-Hettinga equipment. Hettinga also supplies an unidentified "proprietary liquid" that is stored unpressurized, preheated and injected with the melt, turning to gas in an apparent chemical reaction "just like baking soda," according to company president Siebolt Hettinga. The reaction creates low pressure in the part (300 psi vs. 5000 psi for conventional gas-assist) and needs no venting. Hettinga's advantage is said to be less stress, particularly with high-shrink materials. He also says his process is free of the patent problems that have affected the others.
One molder developing automotive applications for Hettinga's process is Andover Industries, Andover, Ohio. Hettinga says five other Big-Three automotive applications are under consideration.
NEW PATENT ISSUES
New patent issues could reopen problems between GAIN and other gas-assist suppliers, such as one on resin overflow - allowing gas to push excess resin out of the gates after the part is initially packed. GAIN sales director Jon Erikson says GAIN's patent on this has been granted and is nine months ahead of an application by Klockner Ferromatik Desma for its Airpress III material-overflow system (PT, Oct. '90, p. 39).
Another potential patent issue is multiple gas-injection ports, said to improve control and permit lower pressures. All new Cinpres licenses including GM and GE, are multi-port, with GE taking the first four-cylinder unit. APT and GAIN both say they have separate multiple-gas-entry technologies, each involving a patented resin reservoir off the cavity. Cinpress still says it has an advantage in using multiple gas-injection cylinders to supply varying pressure to different parts of a tool, though GAIN says it can also apply variable pressure to different parts of a mold using individual pressure controls.
Another potential wildcard is two 1984-85 apparatus and method patents for side-entry pin probes, invented by gas-assist pioneer Jim Hendry, who worked in turn for Cinpres, Sajar and GAIN. Hendry is now a freelance consultant from his home in Brooksville, Fla.
OUT OF THE CLOSET
During the long period when gas assist was tied up in courts in the U.S., but flourishing and available to processors in Europe and the Far East, many U.S. molders played with it in secret. Molders say "virtually everybody" is now looking at the process, at least developmentally. "There's so many of us doing it that after a while it won't matter," was one molder's attitude toward efforts to lock up the technology with patents. It is widely believed that some U.S. molders have automotive gas-assist applications in production - mostly for export - in violation of patents.
How much activity is going on can be surmised from activity at mold makers. "If you go into tool shops, you'll see a lot of molds for gas being built," says one molder who is licensed. Gas injection can be done by modifying commercial presses. Cinpres cylinders, for example, can simply be retrofitted to hang off the outside of existing molds.
The recent feeling of relative legal security following court decisions on GAIN and Cinpres patents is bringing some processors with gas-assist capabilities out of the woodwork. At least one company taking a license has actually used gas-assist on production automotive parts for over two years, though not in a big way. Some molders are advertising or announcing gas-assist services for the first time. Several avenues for "unlicensed" gas-assist equipment are said to exist. "The simplest is a homebuilt gas-assist system, copying an existing system, since the equipment in any case isn't what's proprietary - the method is. Also, some "undercover" reshipment of Cinpres and other European gas-assist equipment from Europe to the U.S. is also said to go on. Ditto for equipment originally destined to the Far East.
Lost-core injection moldings allows intricate parts to be molded in one piece by first molding a metal or polymer core, overmolding it with high-heat resin such as glass-filled nylon, then melting or dissolving the core away without damaging the part. The process, commercial in Europe for several years and under development in Japan, is just beginning to be used to make commercial auto parts in the U.S. Suitable parts are engine intake manifolds, oil pumps, water pumps, and thermostat housings, where a single plastic unit reportedly can save some 40% of manufacturing cost and 50% of part weight vs. a metal part.
"Eventual U.S. market potential is in the hundreds of millions of dollars," says Steven Haycock marketing manager of the Plymouth, Mich., Plastics Div. of Freudenberg-NOK. The parent firm made the first production auto intake manifold in Freudenberg, Germany, in 1989. Haycock says plastic manifolds are expected to penetrate over 50% of the 10-million-car U.S. market by the late '90s. "Parts are projected to sell for $25-40 apiece," he adds, adding up to a $150-million/yr market.
The first production lost-core part in the U.S. is made by custom molder Tomco Plastic Inc., Bryan, Ohio, which last year began molding power-steering inlet pipe adapters (used on 1991 Cadillacs) for General Motors' Saginaw Steering Div. Tomco uses vertical presses with closed-loop controls and removes metal cores using its own proprietary process. The glass-reinforced nylon part consists of a pair of intertwined tubes with grooves inside for O-ring seals. "Given the O-ring sizes, there was not room for collapsible cores. That's the impetus for using lost cores," says Jerry Humphrey, Tomco v.p. of manufacturing engineering. Tomco expects to mold some 240,000 parts/yr for 1991 and 1992 Cadillacs and "has prototyped a couple of other big-time automotives parts," Humphrey says for other production programs being considered by Tomco. The key is to identify a product with a very complex design, used in relatively high volume, he notes.
ALSO IN THERMOSETS
Molding thermoset materials over metal cores eliminates one of the tricker aspects of the process - how to melt out the metal core (usually at a temperature very close to the melting point of the resin itself) without damaging the part. This is the approach being taken at what may be the largest commercial automotive program for lost-core molding in North America to date. It starts production of intake manifolds for 1993 Ford Ranger trucks this fall at a Canton, Mich., plant of Dunlop Automotive Composites Inc., a new Dunlop/Ford Motor Co. joint venture based in Benton Harbor, Mich. Dunlop is also prototyping a water-outlet thermostat housing using lost cores.
Manifolds at Dunlop Composites will be molded of reinforced phenolics on special Bucher thermoset injection molding machines with vertical clamps and horizontal injection units, designed to hold up to 200-lb cores in place. Standard horizontal Bucher TS 265/1800 presses will mold smaller lost-core parts like 1/2-lb water-outlet housings, says Phil Leopold, president of Bucher Inc., Buffalo Grove, Ill. Three metal-dispensing units from Electrovert Metal Dispensing, East Greenwich, R.I., will mold alloy cores.
One of the vertical-clamp Bucher presses and Electrovert's largest metal-dispensing unit (LMD 2000, able to form 200 lb of alloy in a 60-sec cycle) has made prototype parts in Dunlop's R&D lab since late last year, says Electrovert general manager Mark Battista. (Dunlop in the U.K. has made tennis rackets using the lost-core technique since 1980.)
Both thermoplastic and thermoset lost-core parts are in development at Woodland Molded Plastics Corp., Broadview, Ill., acquired last January by Freudenberg-NOK. Several programs for lost-core manifold production on 1995 North American cars are in the works. Earliest commercial production on these manifolds will be in 1994, says Woodland general manager Lee Sinderson. These applications will eventually range from 100,000 to 300,000 parts/yr, Freudenberg says. Freudenberg in Germany uses Battenfeld and Bucher injection molding presses and its own core-making equipment. Woodland uses Bucher and New Britain presses (and previously hand-cast its own cores for prototyping).
Handy & Harman Automotive Group, Auburn Hills, Mich., is also developing several automotive and other manifolds using lost-core molding. A marine engine manifold will be in production late this year. The first automotive parts will be an intake manifold for a 1993 model U.S. car and a fuel-rail delivery system for a limited-run methanol-powered 1993 "California car." H&H bought two Electrovert-MDD metallic core-making systems to be delivered later this year to its Dover, Ohio, plant.
Siemens Automotive Ltd. in Chatham, Ontario, is said to be doing metallic lost-core prototyping work for a 2-liter Chrysler intake manifold. Custom molder CMI International Inc., Ferndale, Mich., is also said to be developing lost-core applications for Chrysler for a 1993 car. And GM is also said to be working on lost-core prototypes for 1995 model cars.
SOLUBLE POLYMER CORES
One problem with metal cores is weight, which necessitates costly robots and sophisticated controls to hold cores in place during injection molding. Plastic-on-plastic molding using a water-soluble polymer core material is one possible answer. Molding of soluble cores made of 25% mineral-filled acrylate/acrylic acid copolymer available from Belland Inc., Andover, Mass., was demonstrated by Ludwig Engel KG of Austria (parent of Engel Canada, Inc., Guelph, Ontario) at the K'89 show in Dusseldorf (see PT, Sept. '89, pp. 14, 42). The core washes away in water and can be recaptured with spray drying equipment, repelletized, and reused. Belland's system is offered by custom molder Cascade for large parts and Suratco of Poynett, Wis., for smaller parts. Acustar Inc., Troy, Mich., formerly Chrysler's inhouse R&D unit, is also said to be studying soluble polymer cores.
Belland's polymer can be molded into core halves on standard injection molding equipment, or one-piece cores can be foamed or molded with hollowed-out centers using gas-assist. A 5-lb hollow polymer core might take 15-20 min to wash out of a part, Belland says. Electrovert's Battista says a metallic core melts out in 90 sec.
If polymer recovery and repelletizing equipment is included, capital investment for a complete polymercore molding cell costs about $2.2 million vs. $1.5 million for metallic core making (based on 60,000-80,000 manifolds/ yr).
PHOTO : Liquid Composite Molding
PHOTO : Thermoplastic Composites
PHOTO : Large-Part Blow Molding
PHOTO : Gas Injection Molding
PHOTO : Lost-Core Molding
PHOTO : Computer-generated diagram illustrates the automated glass-preform technology developed by Admiral Equipment Co. Driven by a PLC, the system can generate a glass charge that integrates up to eight different glass configurations.
PHOTO : The Automotive Composites Consortium, the Big Three's composites technology alliance, has embarked on a research program to fabricate a front-end structural cross member through SRIM. (Photo: Admiral Equipment Co.)
PHOTO : RTM technology is finding numerous low-volume commercial applications, such as hood assemblies for heavy trucks and the structural components and body panels for the new Chrysler Viper sports car. (Photo: ICI Acrylics/K-S-H)
PHOTO : Among the latest TP composite applications is this injection molded head-lamp retainer, now being used on two vehicle platforms. The component is made from Himont's Hi-Glass glass-filled PP.
PHOTO : The "3-D" blow molding process involves draping a parison into a mold cavity. The angled geometry of the melt placement can be controlled by movement of the mold fixture or the extrusion head. (Photo: Placo Machinery)
PHOTO : Blow molded seat backs, made from 25% mica-filled HDPE, will be used on the 1993 Chevrolet Blazer truck and are now employed on the GM Corsica/Beretta platform. (Photo: Phillips 66)
PHOTO : Gas-pressure valves and electronic controls on Battensfeld's Airmould system make it the only gas-assist technology based on delivering a preset pressure. Other system like GAIN, Cinpres, Nitrojection, and Hettinga are volumetric.
PHOTO : Held back by patent uncertainty in the U.S., gas-assisted injection molding of auto parts is flourishing in Europe and Japan. Here European trunk liners are molded in two-cavities using two gas-injection points per cavity. (Photo: Battenfeld)
PHOTO : AMP Industries is developing this lightweight auto seat back for GM, prototyping small sections with gas-assist. The idea is for gas to hollow out the patented geometric grid.
PHOTO : Lost-core molding can convert complex metal assemblies, like this intake manifold, into a single molded plastic part. This six-cylinder BMW manifold is 50% lighter than cast aluminum would be and gives better engine performance because of its smooth inner walls. (Photo: BASF)
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||liquid composite molding, thermoplastic composites, large-part blow molding, gas injection molding, lost-core molding|
|Author:||Schut, Jan H.|
|Date:||Sep 1, 1991|
|Previous Article:||Dramatically new PP alloys, copolymers.|
|Next Article:||Environmental issues top agenda at polyurethanes conference.|