This piece was written by Pat Mahon, Garry Craft and Kelly Balmer of Koller Craft LLC
With gas prices on the rise almost every year, the auto industry is looking for ways to reduce emissions and save fuel. While the engines used today are more fuel efficient than those used in the past, automakers have given cars new features with extra weight, keeping fuel mileage roughly the same. This has led manufacturers to look for ways to produce lighter weight cars, and converting certain metal components to plastic has become a viable solution.
Some parts that were originally made of metal can be replicated or reconfigured to be plastic. Often times, plastic components can maintain the desired strength, while providing more design flexibility than metal. Whether it’s geometry, curves, or molded color, plastic can deliver an aesthetic that metal can’t match. This gives designers the look they want, making it an easy choice for Original Equipment Manufacturers (OEMs).
The conversion process
From top to bottom, plastic can be found in many areas of a vehicle where metal was once the primary material. Plastic is also frequently used with components under the hood. Additionally, dashboards, crosspieces, and door panels that were once made of metal have been converted to plastic in many models. Finally, plastic is used in many parts of headlights and taillights, both inside and outside of these areas.
When deciding whether it makes sense to switch from metal to plastic, it is crucial to fully understand the scope of the project. At the start of the process, the right questions should be asked. What are we trying to achieve by switching from metal to plastic? Is the product trying to be cheaper or better? What is the purpose of the change: cosmetic improvements, weight reduction or increased strength? What is the function of the overall part once created?
Engineers at the OEM level work with resin suppliers and decide what types of plastics can be converted based on the strength of the material and how it looks. Such decisions are made based on a number of factors, including the type of resin, its strength and chemical resistance. OEMs want to duplicate the look of the metal part and need to consider the processes needed to make the conversion, relying on a Tier 1 supplier to make it happen. Level 2 manufacturers help the level 1 supplier achieve the end goal.
Tier 2 manufacturers, such as Koller Craft, supply products to Tier 1 suppliers. Once the OEM or Tier 1 supplier builds the tool on the model, the Tier 2 maker then develops a sample of part and submits it to level 1 before the part is assembled.
The benefits of converting to plastic
The right choice of resin can produce a plastic component that will outperform metal. Plastic parts are generally at least 50% lighter than metal parts used for the same purpose and can be made in smaller and thinner sizes. These factors can be beneficial for auto parts or engines where space may be limited.
Although lighter, plastic can match the strength of metal. It also has more aesthetic options and can be customized to meet specific, structural or operational needs. This can open up options for designers. A plastic part can be created and used instead of designing a component that requires two metal brackets. This means that two parts can turn into one part.
Since plastics come in a wide variety of colors and offer finishes and textures, they can be more attractive than metals. Plastic parts also provide more decorative options, which also adds to their appeal. The aesthetics of plastic parts can be customized through part geometry, curves, molded color, secondary decoration and in-mold decoration.
Converting metal to plastic can also benefit businesses from a financial and logistical perspective. Plastic is cheaper than metal, and companies save money by not having to do any plating on the part. Using plastic can provide faster manufacturing cycles and higher throughput than metal. The precision of injection molding can eliminate processes that can take a long time, such as grinding. When it comes to the aesthetics of the piece, the final colors and finishes can be added to the molding process, eliminating the need for separate laser engraving, painting, or other decorative options.
Corrosion and rust prevention are also concerns that designers don’t have to worry about with plastic because it won’t oxidize over time. This is a common problem with metal.
With a more stable market price, plastic is often more affordable than metal. The injection molding process is easy to repeat, which leads to less waste than the metal often produces. Injection molding can also improve energy efficiency as it requires lower melting temperatures and fewer machining steps are required than when producing metal parts.
As automakers seek to keep creating new brands and lighter models, using plastic on more components is an ideal solution. Along with the benefit of being lighter, plastic can match the strength of metal, provide more design options, be manufactured faster, and be a more cost-effective option.
about the authors
Pat Mahon is the Managing Director of Koller Craft, LLC in the St. Louis suburb of Fenton, Missouri, while Kelly Balmer is the Account Executive there. Garry Craft is the Sales Manager for Koller Craft South in Gadsden, Ala.
Koller Craft, LLC, a Koller Enterprises company, is a family-owned, full-service supplier of injection molded plastic components. Since 1941, it has been committed to providing its customers with the highest levels of service and quality. In addition to manufacturing the product to the proper specifications, Koller Craft also specializes in on-time shipment, customer service, and prompt resolution of issues.