Author Archives

Yesterday, I received this question from a frequent blog contributor… Milan What is the difference between molded-in compressive stresses and molded-in orientation stresses? My Response I will first define the two concepts in practical terms, and then address the differences between the two… Molded-In Compressive Stress – As the polymer fills the mold and cools, the polymer begins […]

I just got this quick question from one of our blog readers… Larry We have a small nozzle mold (0.2oz of Lexan PC) that traps air, but we can’t seem to find a way to vent it. The only success we have had is to reduce the clamp tonnage. Can you briefly state a procedure for […]

This e-mailer had a long question about texture and shininess. I have shortened it to include the critical portions… Nathan The largest part quality issue is shininess in the textured portion of the part. A particular part is molded out of PC/ABS C6600, we have performed some studies and came up with the following conclusion:  The draft […]

I received a question accompanied by a newsletter published by from a prominent author in the plastics industry… Jim In the article, the author suggests that a Full-Taper Nozzle should be used for ABS, and a GP (General Purpose) Nozzle is not appropriate for that material. Should we be using Full-Taper nozzles for all our […]

I received this interesting question yesterday… Nathan Normally, I end filling with a transfer position and end holding pressure with time. In a specific process, using PP and a consistent filling time of 2.80 sec. Using the gate seat study, it was determined that the hold time should be 8.0 seconds. Even though the transfer position […]