New Blog Series: The Designer's Edge

Here's to a new year and a new bi-weekly blog series by guest blogger Randy Kerkstra that will offer ways to design and use the mold for effective troubleshooting and for yielding the largest processing window possible. We appreciate Randy's willingness to share his passion for solving problems and lessons learned throughout his 27 years in mold building and molding. We hope this series begins an ongoing dialogue on how mold shops can have a bigger impact on the molding process.


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I'm Randy Kerkstra. I have spent my 27-year career with injection molds. The first half of my career was in the tool shop building and designing molds. The latter portion of my career has been focused on molding where I maintain and repair thousands of molds per year. This experience has opened my eyes to the mold's true impact on process and product, an impact that has been overlooked by many in mold building and molding.

My passion lies in troubleshooting and root cause analysis for which the mold has always been at the top of my list (and not because the mold was always the root cause, but because it was the first thing I wanted to remove since it was "my area").

This doesn't mean I pushed back and blamed the machine or recommneded to process around the problem, which can lead to a smaller processing window, setting the molder up for quality issues or higher scrap. Instead, I wanted to use the mold to make the processing window as large as possible, and this philosophy has been very successful. 

Thirteen years ago when I left the tool shop,  I thought I had a solid understanding of good tool design, but now I realize I had no idea what a robust tool was or how much it could impact part quality, maintenance and repair. So, the focus of this new bi-weekly blog series will be on using mold design (mechanical/functional) to reduce tool failures and impact part quality.  

Topics will cover many aspects of tool design including steel types, hardnesses and coatings, lifters, slides, hydraulics, cooling, repair techniques, texture, blast medias, hot runners, maintenance, two-shot molds, and much more.  It will also address part quality issues such as gloss, sticking, pin push, splay, jetting and buildup, to name a few, with a focus on how to use the mold to resolve these issues.

To maximize the value of this blog series, we want to establish an open dialogue. Please feel free to post your ideas, suggestions and concerns by commenting to this post. Next Designer's Edge post will be on January 23rd covering flash.