Are GP Nozzles Really That Bad?

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 […]

Causes for Screw Bounceback…

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 […]

Explaining Viscosity In Layman’s Terms

I just received this blog request… AK I just read your past blog on crystallinity, could you briefly provide a layman’s description of viscosity? My Response Basically, viscosity is a measure of a polymer’s resistance to flow. The higher the viscosity, the higher the polymer’s resistance to flow. For example: Honey has a higher resistance to flow […]

Foaming Agents in High Pressure Molding…

A past student of mine recently posed this question regarding an aspect of injection molding which is not commonly discussed… SE I was wondering if you help me locate some references on Processing HDPE and PP with 1% chemical foaming agent? All the information I find focuses on Structural Foam which is a low pressure process. We primarily use high pressure […]

Acceptable Part Weight Variability

Yesterday, I received a question which focuses on the common issue of variability… Nathan Currently we are running a mold (8 cavity) with TPU Estane material with part weight 2.68gms.(Holding time – 5.5sec) Based on the Part 2D drawings the theoretical part weight calculated from 3D Solid works is 2.71 gms. From the gate freeze […]