Plastic Injection Molding Troubleshooting
The first step to plastic injection molding troubleshooting is to check for black spots or brown streaks that appear in the molded part of your equipment. These are typically the result of thermal damage. If this occurs, there are a few things you can do to fix the problem. First, check the material for any contamination that may be causing this. Next, decrease the temperature and the overall cycle time settings. In order to get rid of any possible contaminants, clean out the barrel and the screw. You may even want to decrease the screw’s speed since this has been shown to cause materials to degrade.
Another problem that may need plastic injection molding trouble shooting is blisters on the molded part. These are usually the result of air getting trapped inside the machine. This trapped gas will often appear near the walls, so that is the first place to look. You can begin by decreasing the melt temperature and screw speed settings, while increasing the back pressure and mold temperature. Make sure that the regrind is not too coarse, relocate the gate, and you should see an improvement in the situation.
There are also plenty of plastic injection molding trouble shooting techniques that deal with burn marks or dieseling that can sometimes show up on finished modeled parts. This causes a distinctive burning smell and is caused by trapped gas. It is important that this problem is solved at its root or there may be permanent damage on the molding surface. The following are a few possible ways that you can fix this problem:
• Change the gate’s position or increase its size.
• Make sure that the heater is not malfunctioning.
• Decrease the booster time, pressure, speed, and the mold/melt temperature.
• Improve the venting in the mold cavity. Make sure the vents have not become partially closed over time and if they have bring them back to their original size.
• You can also improve venting by reducing the force of the clamp. This is due to the fact that if the clamp force is too heavy it can partially crush the vents, making them smaller.
• Improve the venting at the location where the burn is found. Placing an injector pin or sleeve near this area can allow trapped gas to escape.
The final tip for plastic injection molding trouble shooting this article will discuss is what to do in case of cracking or crazing. This is caused by a high rate of internal stress in most cases. This situation can usually be improved by the following. First, decrease the injection pressure. Make sure the material is dry. Now, increase the temperature of the cylinder, mold, and nozzle. Finally, check the injection speed and modify as necessary.
Hopefully, these few tips for plastic injection molding troubleshooting have been of help.
