The automotive industry is one of the biggest users of injection molding operations because of how repeatable and scalable the manufacturing method is, all the while, being cost-effective particularly at high volumes.
But before any mold is placed into the machine and the molten plastic is injected into cavities, plastic component design must be performed by engineering teams. Whether it’s an OEM creating the part, a Tier 1 supplier program, or a contract manufacturer like Agape Plastics, component design is a vital part of a successful program.
Agape Plastics highlights key plastic component design considerations for injection molded parts in automotive usages.
Essential Design Principles
Every injection molding project is going to be different, which means varying designs and possibilities. But there is a slew of common characteristics that most if not every injection molded component adheres to.
Perhaps the most important characteristic is incorporating uniform wall thickness. When uniform wall thickness is present in a design, the risk of defects such as sink, warp, and residual stress is greatly reduced. If there needs to be a thicker section in a wall, it’s recommended to use ribs and gradually thicken the section rather than adding more material into a given shot.
If uniform wall thickness is the first characteristic, the second one to note should be including draft on all pull-direction surfaces. This allows for a clean ejection from the mold which gives smooth surfaces and extends tool life, a cost-saving design consideration. Sharp corners should be avoided as much as possible and that’s where radii come into practice as they ease stress concentrations throughout the part while improving material flow during injection.
Structural Features in Automotive Plastic Component Design
Aspects like ribs and bosses are incorporated into design to maintain specific aspects of the design such as wall thickness ratio. For automotive applications, plastic component design should feature ribs that maintain a thickness ratio that avoids read-through and sink on cosmetic faces. Bosses should be placed on supported sections to avoid cracks in the surrounding plastic during clamp load or thermal cycling caused by fasteners.
Where possible, avoid deep, unsupported walls and abrupt section changes to maintain a uniform thickness and appearance. If your design requires holes or side features, it is recommended to align them along the mold opening direction to simplify tooling while lowering side actions.
The Importance of Material Selection
Material selection is one of the most critical, if not the most critical, aspect underneath the design umbrella. Selecting the right material can be the difference between a highly functional part and a part that crumbles under the conditions of its environment. That’s why having detailed knowledge of not just the product’s application, but the environment in which it’s going to serve in is of the utmost importance.
In automotive applications, traditionally plastic component design accounts for a few different materials including polypropylene (PP), polycarbonate (PC), polystyrene (PS), acrylonitrile butadiene styrene (ABS), or a blend of these polymers. The deciding factors in material selection usually comes down to the importance of impact resistance, appearance, heat resistance, and of course, costs.
Components that are under the hood are traditionally engineered polymers rather than traditional polymers as engineered material can withstand heat and chemical exposure better. For interior and exterior pieces outside of the hood, the usage of traditional polymers makes its appearance.
Automotive Constraints
Plastic components used in the automotive industry face some of the greatest challenges from an environmental standpoint with massive temperature fluctuations, differing pressure levels, humidity exposure, and more.
That’s why design is critical to focus on a tighter control of dimensional stability and cosmetic quality. This holds particularly true for interior trim pieces, lighting, HVAC, and electrical housings. The best way to account for these items is by focusing on gate locations and shrink compensation in design rather than fixing the issues during tooling.
Manufacturers that are certified by the International Automotive Task Force, a group of automotive OEMs and national automotive associations in ad hoc, are preferred manufacturers to maximize your project. An IATF 16949 certified manufacturer has quality management systems that are recognized as thorough and productive toward the automotive industry and a manufacturer can create the components necessary for industry giants like the Ford Motor Company or General Motors.
Connect with Agape Plastics, Experts in Automotive Plastic Component Design
Agape Plastics has a storied history and legacy in the automotive industry as an injection molding manufacturing company. When our doors opened in 1973, it took a decade of hard work and resiliency for our breakthrough – two-bolt stud plate that was developed with GM’s Oldsmobile division. This product was patented and became the springboard for a series of insert-molded fasteners that remain the core of our insert molding business.
Since then, we’ve partnered with numerous OEMs and Tier 1 supplier programs all throughout North America creating the components automotive manufacturers need to get vehicles off the assembly line and onto the roads. Part of the process is an intense focus and collaboration on plastic component design. Our engineers work in step with your team to aid in design considerations for any automotive application and work together to create components that can withstand the harsh conditions of the automotive industry.
Contact Agape Plastics today for assistance with your plastic component design.