Three critical measurements on injection molding processes

The key to implementing control of the injection molding process is to utilize a strategy through which we understand the molding process from a plastics point of view. It is extremely important to understand the plastic as it flows through the barrel of the machine and into the mold, as well as understanding how the various variables of the process acting on the plastic material determine the characteristics of the finished plastic part. To achieve the maximum degree of process control and have positive effects on the finished plastic product being molded, it is important to measure and control the plastics variables. The author discusses three plastics variables: plastics melt (stock) temperature, plastics cooling rate, and another related plastics variable: plastics moisture content. One major problem exists in measuring and controlling these plastics variables however, injection molding machines do not have controls marked "plastics temperature" "cooling rate", and "plastics moisture content". The molding machines and auxiliary equipment only have controls that indirectly influence these plastics variables. Because of the interrelationship of these plastics variables, the basic injection molding process is extremely capricious, any attempt to control these plastics variables must seek to isolate them from each other as much as possible. Then, changing one control will not cause multiple effects in key parameters.<>