PT Blog

Tooling: How to Properly Size Gates, Runners and Sprues; Part 5 of 5

This month I sifted through four decades of Post-It notes, hand sketches and photographs to uncover a number of worthwhile tips and tricks related to this five-part series on gates, runners and sprues. Therefore, this month’s conclusion to the series will simply be a bullet-point list of helpful information.

 •  Full-round, parabolic and trapezoidal are the only three types of runners to be used in an injection mold—in that order.

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Materials: Annealing Tips for Semi-Crystalline Polymers: Part 4

High-performance semi-crystalline polymers typically have high glass-transition temperatures. This results in the need for high mold temperatures to ensure that an appropriate level of crystallinity is established in the part. Polymers such as PPS, PEEK, PPA, SPS, and even some PET polyesters fall into this high-performance class where mold temperatures of at least 120 C (248 F) and as high as 200 C (392 F) are needed in order to achieve the desired structure. Some PET suppliers have developed nucleating technologies that allow for development of an appropriate level of crystallinity while still using mold temperatures that can be achieved with traditional water heating.

In the case of PPA, almost all suppliers of this class of materials have developed fast-crystallizing grades as an alternative to the original materials that required the more demanding mold temperatures. However, this improvement was achieved by manipulating the chemistry of the polymer so that the glass-transition temperature (Tg) is reduced. This is something that material suppliers neglect to mention, and while the molder may be very pleased to be able to produce parts without resorting to extreme mold temperatures, the end user may not be so enthusiastic.

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New Mold Grease Smooths Operations for Troublesome Tool

Ask tooling managers to identify their “problem child” tools, and they can quickly rattle off a list of their shop’s difficult molds and each one’s particular issues. William Duffield, tool room supervisor at Erwin Quarder Inc., Grand Rapids, Mich., is no different. After coming to the custom molder at the end of 2017, he sought out the company’s most headache-inducing molds as he worked to augment the company’s preventive-maintenance program.

Erwin Quarder is a full-service injection molder with 32 presses from 50 to 400 tons and just under 100 employees. A primary line of business is overmolding electronic leads for the automotive sector, and most parts are fit-in-the-palm-of-your-hand small. The Michigan plant is a wholly owned subsidiary of Erwin Quarder Systemtechnik GmbH in Germany, which also has facilities in Mexico and Asia. 

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New to Using Color Concentrates? Follow These Tips to Improve Results

As younger engineers and buyers enter the plastics industry, there is a need to provide the next generation with the right fundamental knowledge and awareness to produce high-quality colored plastic parts. Designers and brand owners understand the importance of choosing the right color to ensure their products stand out from the competition. Yet they often may not have enough fundamental knowledge and awareness to produce quality colored plastic parts, and turn to their processing partners for help. With a focus on highly loaded color pellet concentrates, here is a guide for processors of rigid packaging and building products on how to specify the colorant,  along with examples of how processors in these markets are using new color technologies to give their products a boost. Most of the principles discussed here generally apply to other end-use markets as well.

Choosing colors for your products is a critical part of the development cycle. Designers and processors looking for ideas or trends can use sources such as Color Marketing Group, Pantone, paint companies, magazines, and social media.

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New Bioplastics Could Lead to Tougher, More Versatile Medical Implants

Based on a type of nylon, is a new bioplastic recently developed by U.K.’s University of Birmingham that is said to be tough and strong and also easy to process and shape for use in medical implants.

According to the researchers, the material’s shape memory properties enable it to be stretched and molded but able to reform into its original shape when heated. This makes it useful for medical devices such as bone replacements, where minimally invasive surgery techniques require additional flexibility in implant materials.

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