Car door panels are an important part of car interiors. They are located on the inside of the car door and are divided into front, back, left and right. They vary according to the car series, usually two doors and four doors. These parts are collectively referred to as the door panel series.
As a professional injection molding manufacturer, we have participated in the development and production of car door panels many times. The following is a case sharing of the left and right rear door panels we cooperated with a certain car brand.
Project Introduction
The illustration shows the left and right rear plastic car door panel components developed for a well-known automobile brand. The material used is PP+EPDM, with a shrinkage rate of 1.001. EPDM (Ethylene Propylene Diene Monomer) is a type of ethylene-propylene rubber that can be processed by both injection and compression molding. As a copolymer of ethylene, propylene, and a small amount of non-conjugated diene, EPDM features a chemically stable saturated hydrocarbon backbone, with unsaturated double bonds in the side chains, offering excellent resistance to ozone, heat, and weathering. This enhances the elasticity of the custom auto door panels.
Upon receiving the project, our engineering team held meetings with the customer to thoroughly understand the project details and requirements. We conducted an in-depth internal analysis of the product and provided the customer with a professional DFM (Design for Manufacturability) report.
The car door panel is an exterior part with dimensions of 880mm x 670.4mm x 105.6mm. Its structural features are as follows:
- The customer has strict requirements for surface quality. No spots or gate marks are allowed, and defects such as sink marks, weld lines, and flash are strictly prohibited.
- The surface of the automotive door panel features a leather texture, and the exterior side requires a minimum draft angle of 5° for demolding.
- The panel has a high-gloss curved surface and complex geometry. The parting lines are intricate, with a total of 11 undercuts on both the interior and exterior surfaces of the plastic car door, making demolding challenging.
Mold Design and Manufacturing
Given the large size and complex structure of the custom car door panel, our engineering team decided to adopt a hot runner system. Four valve gates are controlled by sequential valves, delivering melt into the cavity through conventional runners and fan gates. There are 11 undercuts on the inner and outer surfaces of the car door interior panel. Among them, only the S11 undercut is located on the exterior surface. For mold reliability and manufacturability, S11 adopts a side core pulling mechanism with inclined guide pins and sliders. The remaining undercuts are released using inclined ejector rods and blocks.
The final mold design measures 1450mm x 1400mm x 985mm, with a total weight of approximately 16 tons, classifying it as a large-size injection mold.
In automotive mold manufacturing, temperature control is critical, as it significantly affects both the molding cycle and the quality of the plastic parts. Naturally conformal cooling channels help improve part cooling efficiency and extend mold life. The customer has strict requirements for the mold, including minimizing or avoiding the use of cooling water wells and sealing rings. Large-diameter wells in excessive quantities can weaken mold strength and shorten its lifespan, while sealing rings are prone to aging and failure, so their use also needs to be reduced.
Our engineers strictly followed the customer’s specifications throughout the mold design and manufacturing process. The final mold and molded custom car door panels fully met the client’s standards, proving our workability as a reliable car door panel supplier capable of handling complex, high-volume automotive interior projects.
Our Expertise in Custom Plastic Car Door Parts
With years of experience in custom auto door panels and injection molding, we offer full-service solutions from DFM analysis to mold making and mass production. Whether it’s car door interior panels, dashboard components, or other complex plastic automotive parts, we are committed to delivering quality, precision, and value.
