02-09-2017, 04:45 PM
A study that took place over a 30-year period (1963 to 1993) by Texas Plastic Technologies * analyzed the causes of the most common injection molding defects. The defects studied were related to the process and did not include those resulting from poor product design. The study found that defects could be traced to problems with one or more of the following four items: molding machine, mold, plastic material, and molding machine operator.
The first step in solving problems is to visualize how a process should be run. Most troubleshooting is actually done after a specific job has been run correctly for an extended period of time. There has been an initial process of preparation and purification, and the mold has been accepted for production. Then, after running successfully, the parts begin to be molded with defects. This is when the problem solver is entered into the image. This is also when simple analysis, common sense and objectivity must be put into play.
By visualizing what happens to the plastic as it moves from the hopper through the heating cylinder and through the flow path to the cavity image, you can determine what may have changed to cause defects. A heater band could be burned, or a spring from the injection pressure valve could leak, or the cooling water lines could have been blocked. Any of these problems will make specific things happen. A thorough knowledge of the molding process will help determine the cause.
The first step in solving problems is to visualize how a process should be run. Most troubleshooting is actually done after a specific job has been run correctly for an extended period of time. There has been an initial process of preparation and purification, and the mold has been accepted for production. Then, after running successfully, the parts begin to be molded with defects. This is when the problem solver is entered into the image. This is also when simple analysis, common sense and objectivity must be put into play.
By visualizing what happens to the plastic as it moves from the hopper through the heating cylinder and through the flow path to the cavity image, you can determine what may have changed to cause defects. A heater band could be burned, or a spring from the injection pressure valve could leak, or the cooling water lines could have been blocked. Any of these problems will make specific things happen. A thorough knowledge of the molding process will help determine the cause.