Finding the Right Alloy at the Design Phase
Optimized Injection Mold Design through Simulation
The Sigmasoft Virtual Molding software from Sigma Engineering GmbH, Aachen, Germany, helps with the analysis and evaluation of injection molds and temperature-control concepts in the early stages of design. It supports the user in determining the optimum combination of tooling alloy and temperature-control concept. The resulting molds thus produce good quality parts on the machine from the start.
Complex Simulation Simplifies Tool Design
In a case example for an automotive application, the mold was first planned using a commercial tool steel. To avoid expensive reworking of the mold, the entire configuration - including all tool components and their alloys - was simulated in Sigmasoft. The simulation operates like a virtual injection-molding machine and simulates a heating phase and multiple injection-molding cycles to reach a thermal steady state. The analysis mold, once the temperature had stabilized, revealed hot spots (Figure: left) where the temperature was up to 30°C higher than in the other parts of the cavity. To achieve more uniform distribution, various possible solutions were simulated and evaluated using Sigmasoft Virtual Molding.
In keeping with the overall mold concept, the preferred solution was to exchange the tool steel for a high-conductivity alloy, instead of using additional cooling channels. For this purpose, virtual experiments were conducted using mold inserts of CuBe B2 and Moldmax HH. As in the first analysis, these experiments, too, were calculated with a heating phase and several injection phases in order to achieve a thermal steady state.
Finally, the temperature distribution at the cores was compared with all three materials. Both high-conductivity alloys show a significantly improved and more uniform temperature distribution (Figure: center and right). Since the temperatures reached by bot alternatives vary within the same range, they both represent a satisfactory solution for avoiding the hot spots. From the simulation results, the mold could immediately be constructed using highly conductive cores, and thereby forms the basis for a stable process.
Sigmasoft provides an easy way for its users to analyze and assess their planned mold configuration even before the mold is constructed. With the aid of the software, the users can identify thermally critical regions and check various potential solutions in order to improve the mold and make the injection molding process more stable. They thus save costs and eliminate the need for revisions to the mold between machine trials.
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