Understanding Runner System Molding: How the Right Runner Design Impacts Every Plastic Part

 If you have ever been confused about why two molds that make the "exact same" plastic part come with very different pricing, cycle times, and scrap rates, it's probably due to one unsung hero of the process: the runner system. Runner system molding, or the science and engineering by which the molten plastic journey takes place from the injection unit to the mold cavity, is considerably more critical to production efficiency than most people imagine. In this article, we take a very hands-on approach to runner systems, discussing how a cold runner injection mold operates, the elements of cold runner solid mold design and at what point a hot runner mold system might be more beneficial on a production run. Runner system molding is "one thing" people don't talk about but one which influences cost per part as well as scrap rates and part quality. When new mold designs are put out for quotation by toolmakers, the quality of the runner is the first point a highly...