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John Bozzelli Founder
Injection Molding: Fill Based on Volume, Not Weight
Most parts should be 90-99% full after first-stage—by volume not weight. Here’s why that’s important and how to make a first-stage-only part.
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Injection Molding: Safety First—Know the Compatibility of Different Resins
Certain materials don’t play well together when mixed. So it’s best not to. Here are some guidelines.
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Injection Molding: Process Documentation Is Crucial to Making ‘Identical’ Parts
Use a machine/mold setup sheet to document plastic parameters and use them on any acceptable machine into which the mold is placed.
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Injection Molding: A Practical Approach to Calculating Residence Time
Toss the formulas. The best way to determine residence time is to conduct a simple experiment.
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Injection Molding: How Backpressure Adjustments Influence Shot Size
Raising backpressure results in increasing shot size, which can cause a host of other problems.
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Injection Molding: How to Set Barrel Zone Temps
Start by picking a target melt temperature, and double-check data sheets for the resin supplier’s recommendations. Now for the rest...
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Injection Molding: Melting Amorphous vs. Semi-Crystalline Plastics
Understanding the differences in how each melts is crucial to obtaining melt uniformity.
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Injection Molding: Nozzle Heaters & Thermocouples: A Case of Wiring Done Wrong
Incorrect placement of wires for these components frustrates molders and costs them money to boot.
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Injection Molding: New Mold Trial—Will It Run 24/7?
Use this nine-step process to make sure you’ll be making good parts after a successful trial. But even then, be prepared for some hiccups.
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Injection Molding: No, Backpressure Does NOT Raise Melt Temperature
It’s a classic confusion between cause and effect. Melt temperature rises when screw speed is increased. Check out this data.
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Injection Molding: DOEs Done Right
Doing DOEs for the sake of doing them wastes time and money. But they can provide vital information to determine which process variable is determining a critical part characteristic.
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Injection Molding: Time for Another Look at Non-Return Valves
First and foremost, they must seal properly, and check valves with stepped angles or radiused seats perform the best.
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