Know-How
Polyethylene Fundamentals – Part 4: Failed HDPE Case Study
Injection molders of small fuel tanks learned the hard way that a very small difference in density — 0.6% — could make a large difference in PE stress-crack resistance.
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How To Design Three-Plate Molds – Part 4
There are many things to consider, and paying attention to the details can help avoid machine downtime and higher maintenance costs — and keep the customer happy.
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What You Need to Know About the Design and Operation of Maddock Mixers
Designed properly, all entering solid polymer fragments and certain types of PE gels entering the Maddock mixer can be trapped and dispersed into the matrix resin. But many are not properly designed. Here’s what to look out for.
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Unraveling the Science and Myth Associated With Moisture Analysis — Part 2
Once you’ve selected the right moisture analyzer, the task of method development begins. Don’t skip this step or you’ll run into problems. Here’s what happened in my lab decades ago.
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Fundamentals of Polyethylene – Part 3: Field Failures
Polyethylene parts can fail when an inappropriate density is selected. Let’s look at some examples and examine what happened and why.
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The Fundamentals of Polyethylene – Part 2: Density and Molecular Weight
PE properties can be adjusted either by changing the molecular weight or by altering the density. While this increases the possible combinations of properties, it also requires that the specification for the material be precise.
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Understanding the Effect of Pressure Losses on Injection Molded Parts
The compressibility of plastics as a class of materials means the pressure punched into the machine control and the pressure the melt experiences at the end of fill within the mold will be very different. What does this difference mean for process consistency and part quality?
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The Fundamentals of Polyethylene – Part 1: The Basics
You would think we’d know all there is to know about a material that was commercialized 80 years ago. Not so for polyethylene. Let’s start by brushing up on the basics.
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How to Start a Hot-Runner Mold That Has No Tip Insulators
Here's a method to assist with efficient dark-to-light color changes on hot-runner systems that are hot-tipped.
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Maximize the Cooling Capacity of Your Extrusion Line
Maximizing output in extrusion requires a thorough understanding of not only the cooling requirements of the extruder but of the extrudate as well.
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