Shorter design-cycle times. Global competition. More tasks to perform, fewer people to perform them. Environmental regulations. Recycling issues. The need to reduce components and speed the production process. This has become a familiar scenario for design engineers over the last few years. However, when it comes to a new-product design that involves plastics, there's an "angel in the outfield." If your project has gotten to the point where it cries out for a crucial decision on what material can best do the job in a cost-effective manner, and your design team disagrees on the final selection, a quick call to a leading plastics producer could provide the solution. In today's competitive world, you will find that a plastics producer's design services address the same demands that the customer's markets address. The fast-paced, global world of automotive engineering provides some of the most interesting examples of how these "partnerships" work. Here's a sampling:
One-piece camper top doesn't leak
Turning plastics product concepts into reality requires expertise in material selections, design feasibility, cost evaluation, process optimization, prototyping, and product testing. At BASF's Plastics Applications Center, Wyandotte, MI, design engineers have access to unrivaled evaluation, design, process, and testing tools, plus a great deal of technical expertise that ensures the success of their ideas. And, if these resources are not enough, design engineers can draw upon BASF's worldwide technical service capabilities and facilities, including major applications development centers in Ludwigshafen, Germany, and Yokkaichi, Japan.
An extensive array of advanced computer tools enables BASF's engineers to provide customers with comprehensive design and engineering recommendations. Using the latest computer modeling and analysis systems, BASF supports the customer from initial concept right through to final production.
For example, BASF performs structural analyses that help optimize a product's performance. Prototyping assists customers in their evaluation of parts under simulated end-use conditions. Processing analyses simulate processing conditions and point out potential areas for optimizing the manufacturing process. The goal: helping the customer make a quality product, using the most efficient manufacturing method, and getting the product from concept to reality as quickly as possible.
An outstanding example of how the resources at BASF's Plastics Applications Center were used involved the development of a recently introduced Colemancamper. Made by Fleetwood Folding Trailer, Somerset, PA, the trailer has a composite top, which consists of an outer shell thermoformed of a coextruded LuranS ASA/ABS sheet; an inner shell thermoformed of ABS sheet; and a rigid polyurethane foam that is injected between the inner and outer shells.
Luran S is used as the exterior surface because it provides excellent weather-resistance. Unlike flat aluminum camper tops that have seams, the one-piece coextruded tops cannot develop leaks.
Engineers at BASF's Plastics Applications Center assisted Fleetwood's engineers in virtually every phase of the product's development. A computer model (PATRAN®) of the roof was produced to allow analysis of the composite top's expansion and contraction at various temperatures. BASF engineers used finite-element structural analysis (ABAQUS®) to evaluate various static and dynamic load conditions in various environments. Then they considered design options (ProENGINEER®) to best meet end-use requirements. These options included different types of materials and material thicknesses and design features.
BASF engineers also provided manufacturing expertise for thermoforming the top. This included developing heat patterns for forming the part with uniform wall thickness and optimum weather resistance.
A key element of BASF's assistance to Fleetwood is its extensive materials database. BASF Plastic Materials has one of the broadest lines of performance plastics available. This enables the company to provide its customers with in-depth material comparisons, based on the same evaluation methods, to come up with the optimum plastic for a product. Whether it's heat, chemical, wear, burning and/or weather resistance, strength, stiffness, toughness, dimensional stability, or electrical insulation properties, BASF can provide reliable and meaningful comparisons.
Evidence of the outstanding potential of BASF's technical service is shown in the fact that BASF has helped customers produce many award-winning products. In 1993 and again in 1994, products BASF helped develop won the prestigious SPE Automotive Division Grand Award for the most innovative use of plastics. The '93 SPE award went to Ford for its front suspension stabilizer link made of ULtraformacetal copolymer, and Elastollanthermoplastic polyurethane. The '94 award went to General Motors Power Train for the air intake manifold made of Ultramidnylon, which is on the Cadillac Northstar V-8 engine.
--Dr. Wolfgang Mueller, Director, Applications Development and Technical Center, BASF Plastic Materials, Wyandotte, MI
Pushing the pedal away from metal
When Ford decided to switch from metal to a plastic pedal assembly and bracket for the 1999 model of one of its top-selling vehicles, the company looked for a supplier to develop a design that optimized mass, strength, and cost. After careful evaluation, Ford turned to AlliedSignal Plastics for its Capron8233, a 33% glass-reinforced nylon 6--and for its design expertise.
"AlliedSignal Plastic offers an innovative design methodology that allowed Ford to achieve its maximum strength to mass ratio at an attractive cost," says Todd Hemingway of Comcorp, the part's molder. AlliedSignal's Modulus group provided complete design support, including pedal assembly design, OPTISTRUCT analysis, finite element analysis, mold design, warpage/strength analysis, and laboratory testing of molded parts.
Engineers at AlliedSignal took on the pedal design challenge after Ford had evaluated several proposals from other companies that took the conventional approach--producing the metal pedal design in plastic. In Ford's opinion, the part was too heavy. So AlliedSignal Plastics design engineers proposed an optimization using computer analyses.
Key to the pedal design was the OPTISTRUCT analysis, according to Cliff Nastas, AlliedSignal Plastics global advance program manager. Rather than adapt the metal design, AlliedSignal engineers chose to start with a clean slate. "The computer searches through available plans for one with the least volume and highest performance," he explains. The resulting design was a C-channel pedal, with the open channel facing the passenger compartment. The optimum reinforcement design was not the expected 60-degree, zig-zag rib pattern, but parallel ribs broken intermittently with a diagonal rib.
The obvious resin choice was the 33% glass-reinforced Capron 8233 nylon 6. It provided the key benefits of superior strength, stiffness, impact resistance, processability, and dimensional stability. Other properties include: unequaled surface aesthetics, and the inherent chemical resistance of nylon 6. "Capron 8233 has been a proven performer for us in a number of automotive applications replacing metal, including interior, exterior, and under-the-hood components," adds Nastas.
Combining the optimum design and resin, the new pedal design tested at 250-lb loads at temperatures ranging from 40 to 180F, well over all standard load requirements. In fatigue testing, the pedal ran through a million cycles at 380-lb loads.
In addition, the design has been driver-tested to allay any possible concerns about consumer resistance. Because the previous metal pedals were fitted with rubber pads, engineers worked to eliminate any possible concerns that the all-plastic pedal would be perceived as too slippery. Tests so far have revealed no negative perceptions, in part because the plastic design promotes upward contact with the pedal.
For Ford, the design resulted in a more efficient accelerator pedal assembly, as well as significant cost savings. "By replacing steel with plastics," says Dean Burchi of Ford, "we've reduced the number and weight of the parts by 50%, and saved 10% on costs."
--Chul Lee, Design Engineer, AlliedSignal Plastics, Southfield, MI
Nylon airs out vacuum-harness performance
The combination of rising automotive underhood temperatures with extended-life warranties has created new demands on thermoplastic materials used in this environment. Operating temperatures routinely rise to 300F and above, with spikes into the 400F range. Also, components must perform to specification for up to 120,000 miles in many cases.
Ford's newly designed 4.6-liter engine, used on 1996 F150 trucks, provides an excellent example of this demanding trend in thermoplastic materials. The vacuum harness, which delivers vacuum from the reservoir to several critical operating systems, sits immediately on top of the engine, where it faces these high operating temperatures.
With a federal lifetime requirement of 120,000 miles for emission components, Ford engineers found that standard nylons used for the vacuum tubing could have difficulty meeting the longevity requirements given the severe operating conditions. As a solution, Ford turned to Stanyl46 nylon from DSM Engineering Plastics.
The long-term heat-aging characteristics of the nylon material ensure that the tubing does not become brittle and crack, causing potential failure of critical systems, such as exhaust gas recirculation (EGR), fuel pressure regulation, and vapor management. Susan Webster, Ford product design engineer for the engine, points out that Stanyl can be processed in the existing extrusion equipment for nylon 6, so no new capital equipment was required to make the switch. "We form and use the 46 nylon within the same design parameters as the nylon 6, which simplifies the design process," Webster adds.
Rigid vacuum tubing such as that used in the Ford harness has been the exclusive domain of nylon 6 for more than 20 years. Therefore, Ford engineers and their processors needed a significant amount of performance and processing data to confirm the viability of Stanyl.
From a performance standpoint, DSM provided customized heat-aging studies that compared 46 nylon to Ford's "incumbent" nylon 6 across a range of temperatures for a 4,500-hour period. "Although we had generated a wealth of test data on heat aging prior to this program, we needed to provide the customer with data that was very specific to the performance environment," explains DSM's Kim Davies, automotive applications development engineer.
Each vacuum tube in the harness is color-coded to indicate which system it serves. DSM also worked closely with pigment suppliers to develop specialized additives that would not embrittle the vacuum tubing. "Colorants are notorious for adversely affecting the properties of thermoplastics, especially in elevated-temperature environments," according to Davies. "Part of our support on the program was to develop new formulations to ensure material performance."
Processing support was also essential in this program, since the tubing manufacturers had worked exclusively with nylon 6 in the past. Leveraging the expertise and test equipment available with sister companies in Europe, DSM ran several design-of-experiment studies in order to optimize process parameters, even though the tubing is produced on several different machines in the U.S. "Because processing is so closely tied to component performance, we provided a tremendous amount of technical support and trouble-shooting," says DSM Technical Support Specialist, Michael Guetling.
The technical support efforts undertaken, while not among the most glamorous, are nevertheless typical of the service required to ensure success for the customer, according to Steve Gerbig, DSM's director of technical support. "Sure our services sometimes include CAE work, but the essential ingredient in a program's success will vary from project to project. If we are true to our mission of providing solutions to our customers' materials challenges, we'd better be ready to provide soup-to-nuts services to support those materials."
Gerbig also points out that the application development process never ends: once a program goes into production, it immediately becomes a target for optimization or "down-costing." In the way of CAE services, DSM offers design assistance, mold-filling analysis (C-Mold from AC Technology, Louisville, KY), and structural analysis (MARC from Mark Analysis Research Corp., Palo Alto, CA). All of these are geared to saving time in bringing products to market by confirming product and processing viability before tooling is produced.
--Tony de Vrught, Vice President, Sales and Marketing, DSM Engineering Plastics, Evansville, IN
Partnerships spur innovations
When suppliers and manufacturers within an industry work to complement each other's efforts to serve the ultimate customer, they more than double their creative power. At DuPont Automotive, partnerships, both locally and globally, have proven the effectiveness of this togetherness.
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Several recent component development programs illustrate how teamwork not only ushers in innovation, but leads to customer benefits.
A major collaborative effort between DuPont Automotive and Bosch Plastics Products brought BMW's costs down for a critical part by one third. DuPont MinlonPA 66 nylon resin was selected for the latest generation of cylinder-head covers on BMW's six-cylinder, inline 2- and 2.9-liter engines. Working together, DuPont and BMW studied the engine's thermal efficiency and vibrational behavior, then developed the component to a fully operational prototype. Bosch developed the manufacturing technology.
All three companies cooperated in the mechanical and rheological design and component optimization. The team effort resulted in significant cost and weight savings for BMW.
DuPont Automotive, Ford, and CMI International combined efforts to produce an all-new polymer composite upper air-intake manifold for the 1996 Ford Windstar. The team selected DuPont ZytelPA 66 nylon for the manifold, which features a split-port induction system. The unique system uses 12 air-intake runners, improving emissions and providing greater engine power. The partnership improved emissions and reduced powertrain weight and cost.
Again partnering with Ford, as well as Montaplast of North America, DuPont Automotive helped develop a composite air-intake manifold that reduced overall powertrain weight and cost. DuPont Zytel PA 66 nylon was chosen for the manifold on the Ford Mustang 4.6-liter engine. The joint endeavor enabled the use of the global technology resources of Ford's engineering staff, DuPont Automotive's materials expertise, and Montaplast's tooling knowledge.
The resulting collaborative effort reduced global development time, eliminated the prototype phase, and reduced tooling costs for DuPont customers. Because of the program's success, Ford has expanded use of the new manifold on several other key model lines.
DuPont operates automotive development centers in North America, Europe, and the Asia-Pacific areas. As one of the largest tech centers in the business, with 650 employees, DuPont Automotive World Headquarters, Troy, MI, offers the industry's most comprehensive customer-support resource. Services include:
Computer-based design, with engineering staff and a product-application showroom on site.
In addition, DuPont spends $1.2 billion annually in fundamental research, and hundreds of millions of dollars to commercially develop new materials, finishes, and technologies company-wide. Such global teamwork efforts continue to lead to success for DuPont Automotive's customers in many other automotive applications. It reflects demand for quality, cost reduction, and weight savings--all key issues in today's automotive community.
--Ken Nelson, Senior Design Program Manager, DuPont Automotive, Troy, MI
Teamwork produces cost savings
At LNP Engineering Plastics, the Customers Applications Center (CAC), an advanced customer service, incorporates the multi-talents of an engineering and design group. Across all markets, the CAC delivers seven engineering services to customers: Part Design, Tool Design, Electrostatic Discharge Engineering, Wear and Friction Engineering, Processing Laboratory, CAE/CAD, and the Engineering Graphical Database (EGD).
Some of the newest services available to customers include:
A Detroit engineering office.
A $120,000 hot-runner, thin-walled, laptop housing that enables customers to try different materials.
Falling dart impact data, stress relaxation data, wear break-in curves, and abrasive wear data added to the EGD.
One of the ways LNP achieves high-quality engineering work is through the continual pursuit of skill-set development in three areas--materials, part design, and fabrication technology. Cross training, formal training, one-on-one sessions, and experience, along with clear goals, are ways that the skill sets of the LNP engineers continually improve.
Lexmark International, Lexington, KY, provides a good example of where a relationship with one of LNP's important customers has grown through cost-reducing efforts, as well as specific engineering projects. The side-plate design for Lexmark's ink-jet printer illustrates how this partnership works.
The side plates had to be stiff and strong enough to attach the frame to the rest of the printer, had to be flat and molded to a specific color and surface finish, and had to meet a specific cost target. In addition, Lexmark wanted to theoretically prove where to place the gate in the molding tool to increase the chance of quick success.
As Lexmark designed the part, LNP designed a specific composite with a proprietary polycarbonate technology--ThermocompDF LEX--to meet Lexmark's requirements. The part design was completed to the point where Lexmark's computer model could be transferred to LNP's CAC computer system.
Within three weeks, the CAC engineers and processing laboratories produced actual rheological data and completed the filling analysis. The analysis included the runner system to measure the total required filling pressure.
The result of the teamwork was flat, quality parts produced the first time the tool was employed. The combination of the exceptional processing material and proper tool design produced a very wide processing window, with a fill pressure of only 28 Mpa. Fill time was only 1.5 seconds for this fairly large polycarbonate part. And the final part had a superior finish, while cycle times to produce it were low.
The actual rheological data for Thermocomp DF LEX was entered into LNP's Engineering Graphical Database for future on-line access by Lexmark. Mechanical properties, such as stress-strain curves at various temperatures, were also entered into the EGD for future structural analysis work.
Lexmark also developed the concept of designing several parts in the two side frames of the new printer into a single piece on each frame. Again, it turned to LNP to make the new design work. As a result of these combined efforts, Lexmark realized significant cost savings--an estimated $1.7 million over the life of the product in reduced tooling and plastics consumption.
--Carl Cura, Manager, Customer Applications Center, LNP Engineering Plastics, Exton, PA