A Solution to a Weighty Problem
More than ever before, automakers are under the gun to improve their car’s efficiency by increasing the fuel economy for all models. In 2012, President Obama finalized standards to increase fuel efficiency to nearly 55 mpg for both cars and light-duty trucks by 2025.
Although there are several ways to achieve this goal, reducing the car’s weight is one of the best – and easiest – ways to improve fuel economy without compromising other design and safety factors. And one of the heaviest components of any car is the powertrain. The powertrain’s weight contributes a disproportionate amount to the car’s overall mass, making the powertrain an area of focus for today’s aggressive automotive part injection molders.
The powertrain is one of a car's most complicated assemblies; it refers to the system of bearings, shafts and gears that transmit the engine’s power to the axle. Recently developed plastics materials can help reduce the number of parts needed to assemble these complex components while also reducing overall vehicle weight.
Plastic is Preferred
Gone are the days when plastic was considered a cheap alternative to non-critical automotive components. Automotive engineers are combining plastics’ unique and variable properties to perfect designs and to improve their products’ efficiencies.
Injection molded plastic components are being used in housings and covers that protect gears and bearings, as well as the bearings themselves. Using plastic reduces weight and lowers assembly costs while also providing an economical material that is capable of durable operation under the most strenuous of conditions.
Plastics in Transmissions
It is not surprising that plastic components have been accepted as substitutes for some metals in transmission components. Plastic’s physical properties of heat and chemical resistance, high strength, impact strength, and molding ease offer the new breed of automotive engineers a flexibility of design unheard of in past generations. Materials suppliers can tailor the performance characteristics of “new” plastic resins to meet any designer’s particular needs. The use of additives, fillers and fiber reinforcements will vary the properties of a plastic to meet specific customer requirements. A good example is the use of Polyetherimide as a component used extensively in transmissions for its superior dimensional, heat, and creep performance. A single injection-molded piece of nylon can replace several steel components.
Molding the Future
For the injection molder of automotive parts, the newly developed raw materials can present a challenge. Many are either carbon or glass fiber reinforced (from 5 percent to as much as 30 percent). These added fibers are abrasive and require specialized molding techniques and designs to mold them efficiently. While these fiber fillers are required to add dimensional stability to the finished component and to increase chemical and temperature resistance, they do not combine intimately with the resin component, which – to the uninitiated and inexperienced molder – will cause havoc to the injection molding process.
The molding company that is eager to gain a foothold in the burgeoning market of injection molding for automotive components must have extensive expertise in the techniques required to successfully mold these relatively new molding materials. The finished automotive components must be produced to exacting specifications and to very close tolerances and must be able to pass close inspection. Quality control and careful production supervision is mandatory.
Future of Plastic Injection Automotive Parts
In an interview with AutoFocus, Dino Tres, the Global Transmissions Business Manager for DuPont Performance Polymers, said: “There is enormous potential for polymers in automatic transmissions and drivelines. Wherever engineers need to take out weight and cost and reduce component size while sealing fluids, resisting wear, friction and loads, and withstanding chemical attack at low and high temperatures—we have the products to do that”
Tres went on to say that the specific gravity of composite plastics ranges from 1.2 to 1.5, while steel is about 8.0. That means using plastic injection automotive parts presents an opportunity to reduce weight by up to 80 percent and cut costs by 30 percent to 50 percent.