The screw does most of the melting, but the barrel temperature should be maintaining the melt temperature. Question: How do I know if there is too much back pressure? My Response: The quick method is to make a significant drop in the back pressure, such as reduce by half (ie. 1000 psi to 500 psi) […]
Category Archives
Plastics Technology
Pressure Setting During Mold Open and Close
The molding machine does it’s best to achieve the set mold open and close speed as long as there is enough pressure available. Question: What is the pressure and speed relation for clamp open and close? How can I make sure that I have enough pressure to satisfy the set speed? Answer: During clamp movement, […]
Watch Your Back Pressure
The fun of molding PP is that it can take a significant amount of abuse during molding and end use, but only if it has been melted properly. Concern: In the past week, two different customers consulted us for assistance in troubleshooting failures with their molded parts. They were both running PP and were both […]
Burn Marks & Weld Line Issues
It is always critical to check your first stage short shot since it affects both mold filling and part packing. Request: Please provide reasons & remedies of burn-mark or weld line problems in plastic (HDPE) moulded product during the injection moulding process. My Response: There are many possible causes, but injection should be checked first: […]
Cavitation Reduction Concerns
Cavitation reduction is not as simple as blocking off a couple cavities and continuing to run. The process should be as close as possible to the original process, but this will require an adjustment to the process inputs. Question: Do you have a good process for blocking cavities? My Response: The process is almost identical […]