By: Randy Kerkstra 20. March 2015

The Designer's Edge: Plastic Part Sticking, Part 1

Pin push on the visual surface.  The stress is from the plastic sticking in the rib detail.

Most of you have experienced issues with a plastic part sticking in the cavity (cover half), core (ejector half), lifters, slides or ejector pins, and a typical response is to polish or add undercuts. However, if you understand how materials react to certain surface finishes and temperatures a more robust solution is possible. 

There are numerous root causes. For example, part design, mold design, lack of cooling, improper texture depth, cutter marks, EDM and surface finish. However, it is important to keep in mind that what works for one plastic material does not necessarily work for others. 

Many process technicians will process around these issues, but that only creates a smaller processing window for issues down the road. If you can learn to understand the variations among different plastics, you can design a better mold and address future issues.

I have always had my focus on the steel to create a large processing window. Whenever you are pushing buttons and allowing the plastic to control the situation, you are not always addressing root cause. This is under the assumption that recommended parameters for the plastic are being used. The concern is when a change to the process is made and it appears to solve the issue, when in reality it is right on the edge of re-occuring.

Oftentimes, a change in water temperature will be made. This is not always a robust solution because if temperatures are offset between the halves, mold wear occurs. Another solution is polishing to address a sticking issue, which can cause pin push. For example, one time I was working on an area and removed the pin push. The process technician said, “Great, thanks." I responded “We're not done yet. We need to prove we have a robust window.” So we increased our pack/hold pressures above our set point to make sure the pin push was still not present. This is an example of the factors that are often overlooked when ensuring an issue is eliminated.

Next month I will dive deeper into some troublehshooting solutions for sticking issues that consider the sticking location (stationary or moving mold half), and plastic material and mold components being used.

Opposite side showing the ejector pins.

By: Christina M. Fuges 19. March 2015

ANTEC Mold Making and Mold Design Conference

Next week at NPE2015 the annual ANTEC conference will take place with a solid moldmaking and mold design program, organized by the Society of Plastics Engineers Mold Making and Mold Design Division. It will take place from 8:30 am to noon on Tuesday, March 24 and Wednesday, March 25th.

Tuesday, March 25 from 8:30am to noon in Room S320G there will be a combined session with SPE's Mold Making and Mold Design and Injection Molding Divisions.

Topics include:

·         Design for Moldability and Profitability

·         Grain Development and Grain Repair on Aluminum 

·         Prototype Plastic Injection Molds Produced viat 3D Printing

·         Thermal Analysis Of Conventional and Rapid Tooling for Injection Molding 

·         Induction Heating Simulation for the Plastic Injection Molding Process 

·         Innovative Supply Chain Management: How Big Data Advances Molders’ Use of Resources and Promotes Competitiveness

·         tudy on the Heat Transfer Behavior and Warpage Result in Small Quantity of Diverse Molded Part Designs with Varying Thermal Property Mold Insert Control

·         Treatment of Mold Components: The Knowledge Advantage

·         Mold Design for Reduction of Offline Assembly and Secondary Operations

·         Fundamentals of Optimized Mold Cooling System Design for Injection Molds

·         Use of Pre-hardened Tool Steel Gives Faster Mold Manufacturing

·         Mold Undercut Solutions - Data Driven Advantages

·         3D Volume Shrinkage Compensation Method in Injection Mold Design Optimization

·         Process Planning of Mold Components with Feature Recognition and Group Technology

Click here for the full program.

By: Matthew Danford 18. March 2015

Plastics Saving Lives (Includes Video)


I like to think that at least a few of the articles I’ve written for MoldMaking Technology have had some positive impact on someone’s business, however minor. Although a regular paycheck is a necessary (and welcome) condition of my employment here, inspiration requires more than just that. I need to feel like I’m making a contribution to something outside myself.

I don’t think I’m alone in that respect. Nor do I think I’m alone in the sense that it can sometimes be difficult to connect day-to-day experience with any broader impact on the world. That’s why I was intrigued to see news about a special demonstration at the upcoming NPE show called “Vinyl Saves Lives.” The demonstration will showcase medical isolation units, protective garments and other products to show audiences what PVC in particular does for the medical industry. Read the press release to learn more.

That news, in turn, reminded me of a video we just released that also highlights a life-saving application in the plastics industry. Developed as a recruiting tool, it focuses on a young team of plastics industry professionals that helped create an IV tube check valve.  Our hope is that it shows promising career opportunities for creative, technology-minded youth who want to make a difference in the world. Check it out here.

(Congratulations to our editorial director, Christina Fuges, for her directorial debut, and many thanks to the various industry players that helped bring the video together, including the American Mold Builders Association, the Society of the Plastics Industry, the Mold Making and Mold Design Division of the Society of Plastics EngineersProject Lead the WayCreative TechnologyNyproMold, and Nypro ). 

By: Christina M. Fuges 17. March 2015

Come Out and Support Education

Mold manufacturers throughout the Midwest region of the country are invited to attend the American Mold Builders Association (AMBA) Chicago Chapter's first annual Supplier Night Fundraiser & Dinner Meeting on Wednesday, April 22, 2015, at Medinah Banquets in Addison, IL.

The purpose of this special event is to support Chicago AMBA Education Committee's continuing efforts to promote mold manufacturing as a viable career. Specifically, all proceeds raised from this event will be used to host a symposium in the fall of 2015 where teachers, counselors, parents and students can learn about mold manufacturing careers and opportunities. [On that note, take a peek at our MoldMaking Matters: Your Career Can Make a Difference video recruitment tool produced by Creative Technology of which the AMBA was a sponsor.]

Equally important is the opportunity to bring major supplier companies together with their customers to network and display the latest products and services for molding and mold building in an intimate setting. To date, 28 mold industry suppliers have been confirmed as exhibitors! The program will start at 4pm with supplier booths, networking, open bar and door prize raffle for mold manufacturers and their employees. At 6:30pm  the buffet dinner begins and then from 7:30-8:30pm Jim Nelson, VP of External Affairs for the Illinois Manufacturers' Association will speak.

While the Networking portion of the event is free to mold builders and their employees, the Early Bird cost for the full event is $50/person until April 1st. After April 1st the cost per person goes up to $60.00. For more information call 708-227-0373 or email and visit



By: Matthew Danford 16. March 2015

A Comprehensive Plastics Education at NPE


Regular readers might be familiar with Pellet 2 Part, a series of articles covering the injection molding process. There’s a reason why a magazine called MoldMaking Technology has expanded coverage beyond just the tool—namely, the fact that making the mold is often no longer enough. As many readers can attest, sampling, flow analysis, engineering and other front- and back-end value-adds are now part of the job description.  

Beefing up knowledge of these areas is one reason you might be planning to attend NPE this year. If so, don’t miss out on the chance to deepen your broader plastics education at the PT Knowledge Network. Named for our sister publication Plastics Technology (PT) and hosted at booth W-2602, the network is designed to help plastics professionals to connect with the information resources they need.

Perhaps the meatiest offering is a series of presentations, which are scheduled throughout the week and tend to run about 45 minutes each. Topics include calculating shot size vs. barrel capacity, gate geometry, drying PET, solving extrusion problems, workforce development, additive manufacturing, and reshoring. Given that I work for MoldMaking Technology, I’m particularly interested in the presentation on “thinking in plastic” rather than in steel (which, in essence, is what we’re trying to do with the aforementioned “Pellet 2 Part” column).

At the least, stop by, have a drink and some refreshments at the bar, check out our multimedia displays, do some networking, and sign up for the various prizes and giveaways. I promise it’ll be well worth your time.

The PT Knowledge Network is presented by Plastics Technology in association with MoldMaking Technology, Modern Machine Shop, CompositesWorld, Automotive Design & Production and Additive Manufacturing. Learn more and register here

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