Extruder Screws

For several months now I have written articles which are bits of advice that I hope can be used to improve a process issue, but this month I want to pass on an experience that happened to me [...]

The most common base material that extrusion, blow molding and injection screws are manufactured out of is 4140 HT Steel at a 28-32 Rc condition. This grade of 4140 has a yield strength of 95-100 [...]

“First you must feed the polymer Consistently” Material Handling The material handling of the feedstock is a very critical part of the extrusion process. If the feedstock is not introduced to the [...]

Many people don’t realize the importance of making sure that the screw flight diameter clearance has a significant effect on the performance of their screws. There are some companies that do pull [...]

There are basically three Coefficients of Friction (Figure 1) that take place in the feed section of the screw, (1) between the barrel and the pellet, (2) between pellet to pellet, and (3) [...]

Screw and barrel wear is critical in all plasticating applications whether it is extrusion, injection molding, and blow molding, plus twin screw extrusion. Excessive screw and barrel wear can [...]

Almost all processes, extrusion, injection and blow molding require that regrind be used in the process. Depending on the process greatly determines the amount of regrind that is generated. Some [...]

I have written in the past about screw/barrel wear and also screw rebuilding, but there are some screw and barrel shops that offer an alternative for excessive barrel wear and that is honing the [...]

Recently a processor installed a new screw into their 6” x 32:1 L/D extruder. Within a few weeks the hard facing that had been welded on the flight OD started to pop off. The flight failure was [...]