Case Study: Advanced Overmolding

It's known that not all injection parts challenge the technical acumen of the tool maker and molder, but there are some that do. In this article, an actual example of overmolding will be featured to highlight advanced overmolding.

Some definitions to clarify ahead. Insert molding and dual-shot molding are both processes that form a part binding  multiple components together. Dual-shot molding usually requires a particular type of machine that can rotate the platen or move the core. (Some move the core out the mold and some don't.) Insert molding is a process having inserts placed into the tool,by hand or automation, before molding. They could be further classified by different material combination but they are not the focus of this article.

The part shown in the above picture was introduced at CES 2018 as an in-ear earphone that is tailored for athletes with ultimate comfort and convenience. From perspective of injection molding, this is an example of a mix of various types of insert molding and overmolding. In total, there are six components in one part: PC window, PC-ABS shell, silicone neckband, magnet, cable, TPE cover.  The TPE overmolding is the last step, which connects all other components to make one integrated part.

For tool making, this part has a very complex parting line, as shown in green, requiring very careful works in tool fitting to control flash, mismatch and seal-off. Multiple components in one tool also increase the complexity of mold flow, hence hard to simulate and make molding parameter adjustment more delicate.

Over the past decade, Chinese manufacturers have collected many experience in tool making, molding and quality control and evolved to make more advanced goods. As for the massive size of the Chinese manufacturing sector, the level of capability and specialty varies. CN Mould & Plastic Limited is the one that has its core competency in insert molding and overmolding, in terms of mold structure innovation, problem solving and excellent communication. Owning over 130 molding machine, from 18 tons micro molding press to 1200 tons press, we are capable to offer a comprehensive service from tool design to sampling, and mass production molding. Click the button below to view more of our products.