PT Blog

Tooling: How to Properly Size Gates, Runners and Sprues, Part 4

In part one of this series (in March) I discussed the importance of proper gate depths and gate widths. In part 2 (April) I covered two different types of gates, as well as gate land length and gate-freeze time. In part 3 (May) I discussed edge gates and runner sizes. This month I will discuss runner surface finish; dispelling some bad advice; and how to size the sprue bushing.


Several industry experts say the runner channels should be polished to the same surface finish as the cavity, or between 5 and 50 micro-inches (RMS). This reportedly is necessary to minimize the pressure drop and help with release from the mold. Even if this theory were true, I would suspect it would be almost immeasurable and most likely inconsequential.

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Attention Moldmakers: Amerimold Goes Live

Starting June 9th at 9:00 EST, Amerimold will be going LIVE with its first session, Tool Room LIVE, streamed on www.amerimoldexpo.com . Additional live sessions will follow at 11:00, 1:00 and 3:00 EST every day through Thursday, June 11th.

Amerimold Connects is a five-day online event with scheduled live demonstrations and presentations with Q&A, an extensive searchable menu of on demand content, a forum for networking and continuing Q&A and conversations and exhibitor technology showrooms.

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Part 3 Materials: Annealing Tips for Semicrystalline Polymers

Annealing of amorphous polymers is typically performed to reduce the internal stress in a part below the levels achievable during the molding process. However, in semicrystalline polymers the objective of annealing is to establish a level of crystallinity that cannot be practically obtained within the parameters of a normal molding cycle.

Each semicrystalline polymer has the ability to crystallize to a certain extent that depends upon the chemical structure of the polymer chain. HDPE has a flexible, streamlined chain that allows for efficient crystallization to a very high percentage, while a material like PEEK attains a modest level of crystallinity even under the most carefully controlled process conditions.

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By: Garrett MacKenzie 6/5/2020

Fundamentals of Proper Press Shutdown

Fundamentals of Proper Press Shutdown

In the fast-paced world of injection molding, the key drivers of a plant’s profits are downtime, efficiencies and scrap. A company’s success relies heavily upon quick and efficient startups. Elimination and avoidance of unplanned downtime events also plays a critical part in profitability.

Press shutdown procedures have a significant effect on achieving smooth machine startups and restarts. Moreover, presses shut down poorly quite often lead to process failures and downtime. This article will outline potential downtime events that have a direct relationship with poorly performed press stops. It will also provide a solid approach based on time that will help to reduce, and in most cases eliminate, scrap and downtime associated with press shutdown.
 

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Recycled Resin Gains Molder a Green Niche

George Staniulis often encounters a certain skepticism about his company’s business model. He is vice president of custom injection molder AGS Technology Inc. in Batavia, Ill., which specializes in turning plastic waste into automotive components. Many aspects of the recycling industry have changed over the 25 years that AGS has been in business, but one particular concern from customers has not. “The question always comes up: ‘What happens if you can’t get the recycled material,’” Staniulis says. “So we say that, ‘If we can’t supply recycled, we’ll use virgin and there’ll be no cost penalty to you.’ And that—knock on Formica—hasn’t happened.”

 Staniulis and AGS co-founder Christopher Racelis have more than 70 years of combined experience in plastics recycling. Today, Staniulis and Racelis are injection molders, but they began life in the plastics industry as compounders. In fact, it was experience in compounding with recycled resin as a feedstock that pushed them to start AGS and deflect the “finger pointing” that often accompanied the use of recycled resin, particularly when it went awry.

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