Know-How
How to Get Rid of Bubbles in Injection Molding
First find out if they are the result of trapped gas or a vacuum void. Then follow these steps to get rid of them.
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Understanding Strain-Rate Sensitivity In Polymers
Material behavior is fundamentally determined by the equivalence of time and temperature. But that principle tends to be lost on processors and designers. Here’s some guidance.
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Density & Molecular Weight in Polyethylene
This so-called 'commodity' material is actually quite complex, making selecting the right type a challenge.
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Creating a Capable Process Using Process Capability
Know your Cp from your Cpk and how parts can meet dimensional specifications but still not be “capable.”
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Extruding PCR? Consider a Vented Extruder
You’ll need two-stage screws to extract volatiles that post-consumer reclaim will likely contain. Screw design can be a complex balancing act. Here’s what you need to know.
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Tracing the History of Polymeric Materials: Aliphatic Polyketone
Aliphatic polyketone is a material that gets little attention but is similar in chemistry to nylons, polyesters and acetals.
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Cooling Geometry and the Reynolds Calculation
The original Turbulent Flow Rate Calculator worked well with a round circuit diameter, such as a drilled passage, but not as well using hydraulic diameters. Here’s how the problem was fixed.
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Molders’ Block: Dealing With Foreign Materials in a Hot-Runner System
Understanding plastic flow can help you understand how foreign materials move—or don’t move—through your hot-runner system.
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Tracing the History of Polymeric Materials: Acetal
The road from discovery in the lab to commercial viability can be long, and this was certainly the case for acetal polymers.
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The Importance of Viscosity in Melting
The calculations required to determine the right melt temperature for each polymer are complicated. Knowing the power-law coefficient and the consistency index of the polymer you run might prove useful.
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