The custom front bumper is one of the most essential exterior components of a vehicle. It must provide sufficient strength and rigidity to absorb impact during collisions and protect the body structure, while also serving a decorative function that harmonizes with the overall vehicle design. At the same time, lightweight construction is a critical goal. In order to achieve these goals, the main body of car front bumpers is currently made of plastic, commonly known as plastic car bumpers, which are injection molded by an injection mold.
As a professional automotive parts manufacturer, we have been deeply involved in the development and production of custom front bumpers. The following is a case study of one of the projects we were involved in.
Plastic Front Bumper Overview
Plastic bumpers for cars are typically made from PP (polypropylene) blended with rubber and mineral additives such as EPDM and talc. These materials offer excellent elasticity, strength, and moldability, making them ideal for thin wall injection mold. A plastic car bumper must be impact-resistant, lightweight, and have a high surface finish to meet both safety and aesthetic standards.
Car Front Bumper Structure Analysis
The front bumper in this project features a saddle-like shape. It is made of PP + EPDM-T20, with a shrinkage rate of 0.95%. PP stands for polypropylene in Chinese and is the main material of the bumper. EPDM stands for ethylene propylene diene monomer rubber in Chinese, and it can improve the elasticity of the bumper cover. T20 refers to the addition of 20% talcum powder to the material and it can improve the rigidity of the bumper cover.
Key features of this plastic front bumper include:
- Large size and complex shape, with relatively thin walls, making it a typical thin-walled, large injection molding plastic part
- Multiple holes, punctures, and reinforcing ribs result in high melt flow resistance during injection
- Three undercuts on the inside of the plastic part, and lateral core pulling at each location, is quite difficult
WEe have organized design tips for thin-wall injection molding parts, read our blogs to learn more.
Mold Structure Analysis
Our engineers analyzed and designed the mold in detail based on the plastic part structure. After communication with the client, the final design was confirmed.
The injection mold for the plastic car bumper uses an internal parting surface, with a hot runner system controlled by sequential needle valves. Side undercuts are resolved using a composite angled core system combining large inclined lifters, side slides, and direct pushers. The mold measures 2500mm × 1560mm × 1790mm, which is typical large thin wall injection mold.
Car Front Bumper Mold Design and Production
To ensure optimal molding quality and efficiency, we made comprehensive improvements to the mold design. Each innovation was aimed at enhancing performance and stability, as detailed below.
- Internal parting technology was used to meet the client’s surface quality expectations.
- A secondary core-pulling system with “composite angled lifters” resolved complex undercut structures.
- The 8-point sequential valve hot runner gating system ensured stable material flow in large thin wall injection molding.
- The mold uses hydraulic pressure as the power of the demoulding system to solve the problem of large demoulding force and difficult reset of the front bumper.
Project Outcome
Once in production, the mold demonstrated stable and reliable side core-pulling actions. The resulting custom front bumper products met strict dimensional accuracy and consistent quality standards. This project exceeded client expectations and subsequently, we jointly developed a number of automotive injection molding products with the customer.
Conclusion
With decades of experience in designing and manufacturing plastic bumpers for cars, we specialize in developing custom front bumper solutions that meet demanding technical and visual requirements. From thin-wall injection mold design to mass production, we offer end-to-end support for OEMs and automotive brands worldwide. Partner with us for reliable, efficient, and fully customized plastic front bumper solutions.
