Know-How
Why (and What) You Need to Dry
Other than polyolefins, almost every other polymer exhibits some level of polarity and therefore can absorb a certain amount of moisture from the atmosphere. Here’s a look at some of these materials, and what needs to be done to dry them.
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What is Backpressure and How Should We Calculate It?
Does using an intensification ratio to calculate backpressure result in an accurate reflection of what’s happening in the barrel? Newer machine technologies have us revisiting an old project with fresh eyes.
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Tracing the History of Polymeric Materials: The Commercialization of Acrylic
We covered the invention of acrylic in our last installment. Here, we discuss its commercial development.
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What to Do About Weak Weld Lines
Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate.
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Smaller Screws Impose Bigger Challenges
Very small extruder screws work just about like their larger cousins, but some critical differences make them harder to design and machine.
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Are Your Sprue or Parts Sticking? Here Are Some Solutions
When a sprue or part sticks, the result of trying to unstick it is often more scratches or undercuts, making the problem worse and the fix more costly. Here’s how to set up a proper procedure for this sticky wicket.
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How to Estimate and Control Head Pressure
You rightfully worry about melt temperature, but don’t overlook head pressure, because the two are closely linked and will influence line performance.
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Melt Flow Rate Testing–Part 1
Though often criticized, MFR is a very good gauge of the relative average molecular weight of the polymer. Since molecular weight (MW) is the driving force behind performance in polymers, it turns out to be a very useful number.
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The Scoop on Screws
The kind used as fasteners in molds, that is. Here are some design considerations to help you choose and use the right ones.
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