Page 76 - Injection Molding Advanced Troubleshooting Guide

60 7 Venting

Another option for increased venting is to use a molding machine with injection
compression or coining option. In injection compression molding the mold is not
completely clamped during the initial filling of the mold, which allows for easy
evacuation of the gas within the cavity. The mold locks up under tonnage after
filling to a point and provides for the ability to pack out the part using the force
generated by the clamp (the compression side of injection compression molding).

„ „7.3„ Venting Conclusion

Venting is critical for producing quality parts. Spend the time during mold design
reviews to ensure that adequate venting is provided on all molds. Vents must be
maintained during the life of the mold to provide proper gas evacuation and should
be kept clean during all mold runs. Checking for vent cleanliness is one of the 4M
Basic 8 troubleshooting steps and is a quick step that often eliminates many pro-
cessing problems. Do not process around venting issues: the problem will only get
worse over time!