Feature Articles - The Reum Group

Flow analysis helps The Reum Group beat the costly guessing game.

“When I’m molding a very complex part with 12 different dimensions at ± .001” tolerance, I can’t play every tight tolerance ‘steal safe,’ “ says Mark Dirr, Manager of Process and Tooling Development at The Reum Group.

Like many manufacturing engineers in this tough economy, Dirr feels the pressure of justifying the costs of mold analysis vs. taking the risks of trial and error. Dirr uses flow analysis to help him make decisions on complex parts. He says, "Guessing becomes extremely costly and takes too much time". The only smart way to play it is with flow analysis all the way through shrinkage and warpage evaluations.”

The Reum Group is a manufacturer of common use and custom switches for the appliance and automotive industries. Recently, they were molding a custom door latch for passenger doors of GM vehicles. The latch is an electronic component carrier containing eight metal traces embedded in the molded plastic part. Dirr had many concerns when evaluating the tool design for the latch. Insertion of the metal traces made shrink rate and cycle time critical considerations. The traces had to be in very specific locations, and the injection molding had to be properly timed with all other metal stamping and robotics processes both upstream and downstream of the molding press.

Warpage was another concern because the glass-fiberfilled material tends to shrink at different rates in different directions. Just to make things a little more interesting, the product needed to get out much faster than what was originally projected so the product development cycle was significantly compressed.

Dirr relied on his 10-year relationship with CAE Services to point him in the right direction. CAE provides simulation technology that transforms molding from art to science. In addition to their comprehensive analysis services, CAE’s engineers get thoroughly involved in a customer’s problem to create part design and molding solutions. According to Dirr, “CAE really helps with interpreting the results of analysis. The communication is excellent, and they come up with creative solutions to my molding problems.”

Although he had never used flow analysis to this extent before, Dirr was confident that it would ensure the dimensions were in the right position, which would ultimately minimize the cost and time to build. His instincts were right on. "The shrink rates got us as close as possible to being perfect the first time around. Only minor adjustments were required after the fact, and we did not have to change the tooling."

Due to the electronic components, the part had to be environmentally sealed using pin-pull technology. This technology can create leakage points, but flow analysis helped to prevent this problem by predicting how the metal traces might move. “The warpage analysis was absolutely critical to the product development process”, said Dirr. “If we hadn’t done it, we could have seriously damaged our relationship with the customer.

We accurately predicted warpage would occur, but there was little we could do about it in the time frame we had. We were able to warn our customer so we could work together to resolve the issues before we got too far into the program.”

Dirr says he’d like to use flow analysis for every project, but current industry pressures to cut costs don’t always allow it. For now, he’ll continue to rely on the technology for his most complex challenges, saying, “There’s no way you can quickly and accurately get through a project this complex without doing a complete flow analysis.”