Engineering Challenge: Solving Ejection Issues for a Transparent PC Injection Mold

In plastic injection molding, complex product structures and strict cosmetic requirements often create significant challenges for mold engineers. Recently, we worked with a Japanese customer in the foot massage equipment industry on a high-quality transparent PC (Polycarbonate) component.

The product required a completely transparent appearance, meaning any defects such as sink marks, warpage, flow marks, or surface imperfections were unacceptable. In addition, the part structure created a difficult demolding challenge. Because of its large transparent surface area, the molded part could easily stick to either the cavity side or the core side after injection, causing instability during automatic production.

During the mold design stage, our engineering team carefully analyzed the part retention behavior and mold opening process. The key challenge was ensuring that the product would consistently remain on the correct side of the mold after opening.

To solve this issue, we developed a special synchronized front mold side ejection mechanism. During mold opening, the front mold ejection system works simultaneously to release the product from the cavity side and guide it to remain on the core side. After that, the standard injection molding machine ejector system completes the final ejection process.

This solution improved mold reliability, reduced the risk of part deformation, and ensured stable automatic production while maintaining the high optical quality requirements of the transparent PC material.

This project reflects our approach to mold manufacturing: combining product analysis, mold structure innovation, and manufacturing experience to solve complex challenges before mass production.