In the process of injection molding, it is often necessary to create special patterns or symbols on the surface of molded parts, such as handles, bottle caps, and buttons. So, how are these special threads formed? This article will introduce three commonly used methods for thread forming on plastic parts in injection molds.
There are three main methods for forming threads on plastic parts in injection molds: direct forming during molding, mechanical processing after molding, and using metal thread inserts.
Direct Forming During Molding: This method is simple to process, low in cost, and has a short production cycle. However, due to the nature of plastic materials, the threads formed directly have relatively poor strength and low precision. Therefore, this method is more suitable for applications where the strength requirements for the threads are not high.
Mechanical Processing After Molding: When direct forming is difficult to meet the requirements for thread forming, we can choose the method of mechanical processing after molding. This method requires secondary processing after the threads are formed, so the production efficiency is relatively low. It is usually used in cases where the thread hole diameter is small and deep, the thread core stiffness and strength are insufficient, or when a thread core needs to be installed on the side, resulting in a complex mold structure.
Using Metal Thread Inserts: Metal thread inserts have the advantages of high precision and good strength. However, during the molding of plastic parts, stress is easily concentrated around the inserts, and processing and installing the inserts increase the production cycle and cost. Therefore, this method is usually used in threads that require high fitting precision, frequent assembly and disassembly, and are subject to large forces. Especially when the threads are too fine to be formed directly, resulting in insufficient strength for use, metal thread inserts should be used to ensure the quality and performance of the plastic parts.
