Inject Engineering bringing work to U.S. moldmakers

Sometimes old dogs do learn new tricks, and start new businesses to make those tricks pay off.  John Linder, who turns 59-year-old this week, has had a long career in mold design and manufacturing, and injection molding for a number of different companies over the years including Plastech Corp. and Chemtech Plastics Inc. On March 11, Linder (, along with a partner, opened Inject Engineering LLC, located in Rockford, IL.

Linder’s philosophy has always been that molds need to be built from the molder’s perspective and he has made this the guiding business philosophy of Inject Engineering. “What we’re doing is the engineering, and we’re engineering molds from the molder’s perspective rather than the moldmaker’s perspective—designing for optimum molding performance,” he explained. “Our approach to designing will be different than anyone’s in the industry.”

Using the customer’s 3D model and 2D drawings, Inject Engineering runs a mold filling analysis and material flow simulations, identifies the proper gating and venting, locates cooling lines, and performs some "what-if" scenarios to ensure optimum molding performance. By using computer analysis to optimize the mold for the molding process, he can predict the widest possible processing window so the mold can be designed to that. Linder also notes any discrepancies in the product’s design that might inhibit its manufacturability, collaborates with the customer to make changes.

“Engineering the mold up front—including having accurate predictions for shrinkage and warpage tendencies prior to starting the design process—saves time spent debugging and fixing mold and part geometry problems after the mold is built,” said Linder.

Once the mold has been engineered for optimum molding processing, Linder sends all the computer simulation information along with the narrative, the Bill of Materials, mold component specifications and a 3D model of the part from which the mold will be built, in a power point presentation to a large mold-design firm in Shenzhen, China, with which he has worked in the past.

“They send us back the model of the 3D mold that they have designed,” Linder said. “Our goal is to have a preliminary mold design completed within 48-72 hours.”

Upon completion of the mold design, Inject Engineering conducts a design review process which is based on a tooling FMEA. “We look for any possible failure modes and ensure that they are designed out of the tool,” Linder said. “If we see a problem we make changes and send those back to the designer. Once we are sure the mold meets our critical design standards, we submit the design to the client for approval.”

Linder emphasized that Inject Engineering is not designing in China to build in China, which is the typical scenario. “We’re designing tools to have them built here in the United States by U.S. mold companies,” he said. “There are some unique challenges to doing this because Chinese designers are used to designing molds to be built and sometimes even run in China. We’ll create the catalog of components and specifications for each mold, and ensure that those are adhered to.”

While Linder admits that his is a

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