Shadowing vs. On-The-Job Training…

I would like to relay a common misconception I hear on training and clarify two forms of ‘training’ often used my plastics companies… Joe We currently train our people using on-the-job training, we have a new employee follow another employee around for a couple days. My Concern Most people equate ‘shadowing’ with ‘on-the-job’, or OJT. According to Merriam […]

Drying Nylon with a Hot Air Dryer…

This question came from a molder overseas… JY We typically process polypropylene and polyethylene but our customer asked us to run Nylon. Can we use a hot air dryer for nylon? My Response Hot air dryers are typically used to either remove surface moisture or preheat the polymer.Since they do not significantly reduce the dewpoint of the […]

Calculating Part Shrinkage…

This question overshadows a common mistake made by many molders and designers… Steve What is the correct way to calculate shrinkage? One engineer insists that you divide the mold dimension by the part dimension and eliminate the one, but this sounds weird. My Response Shrinkage is a measurement based on change, and is a represented as either a ratio […]

Establishing a Fill for Injection Compression…

I was recently asked a few questions via email, this is one part of that email…. Nathan Are these still correct with Injection Compression? – Relative viscosity fairly constant during even with low fill speed – Fill volume 95-98%  My Response Basically, you are correct, the first stage fill should use velocity control, but you […]

Handling Units…

This was received as a follow-up question to a previous post on … Joe How do you explain the basic rules for handling units in calculations? My Response We have training courses which cover this and other topics in detail, but I’ll cover the basics here. When multiplying and dividing numbers with units, the units are either combined or […]