You should always transfer from injection to packing with all cavities short-shot. Question: Let’s say a mold is imbalanced, the injection speed is 4 IPS and the mold is filled to 95% full. The first cavities finish filling at one speed and the last cavity to fill would fill faster than the first cavities. Why […]
Category Archives
Plastics Technology
Improving the Strength of Ribbon
Increasing the rate of production is an easy way to increase the linear strength of an extrudate. Question: We are blending 3 different types of PE as well as adding rubber to produce a decorative ribbon. Should we also add a grade of PP to increase the product strength? My Response: Blending more materials would […]
How is Clamp Tonnage Adjusted?
There are two types of systems used to generate tonnage, Hydraulic Cylinders and Toggle Linkage Systems. Many toggle systems used hydraulic cylinders to actuate them, but the actual tonnage is applied through the mechanical advantage of the linkage system. Question: How is clamp tonnage adjusted? My Response: On a toggle clamp, the tonnage is generated […]
How is Toggle Clamp Tonnage Measured?
With toggle clamps, the only way to measure tonnage is to measure the strain (stretch) of the tie bar. Question: How do you measure the tonnage on a toggle molding machine: My Answer: With toggle clamps, the only way to measure tonnage is to measure the strain (stretch) of the tie bar. Using the strain […]
Short Shots to Correct Flash
The first step in troubleshooting flash is to determine whether it is a filling problem or a packing problem. Question: I have a part with flash. It ran many times in the past without flash, but recently we have been using a new machine and it is often creating flash. We have tried many adjustments […]