Silver streak troubleshooting of injection molding
There is a list of things to look at when you do troubleshooting on silver streaks. For example: 1) Material is not dry enough, masterbatch also need to be dry. 2) Gate size is too small to cause high shearing rate, then material break down. 3) Melt temperature not to be too high. 4) Back pressure too low make air come in. 5) Runner has shape edge. 6) Injection speed too fast. 7) Last factor maybe material is not good. Look on the web for many excellent troubleshooting guides.
First of all, this defect is commonly known as splay – it is often due to wet material or contamination. Before you go and start doing lots of troubleshooting in the processing set-up, I suggest that you look at whether the material is properly dried before processing, whether you may have contamination from other materials, or see if you purged adequately before the current job. When you look at the material to see if it is wet, also check that any color used is also dry if you are blending it in. Thorough cleaning of any dryers and feeders is also an absolute before material is placed into them for conditioning.
Look at your molding machine, if you are using a vacuum system to feed the material into the injection molding machine, make sure that lines are clear. Then look at the injection mold to make sure that the mold is not leaking water into the cavity, or that you have condensation in the cavity between shots. Only after you have satisfied that you have eliminated these caused factors should you then start in on other parameters in your processing.