| The bezel for a truck instrument panel was in-mold decorated. The process starts by printing, coating, or pigmenting a thin plastic sheet. The sheet is then die cut into a blank and thermoformed to take the shape of the final part. After trimming, the thermoformed sheet goes in an injection-mold cavity. |
Simulation software that pinpoints problems in molding helped Tier 1 supplier OEM/Erie Inc., Erie, Pa. (oemerie.com), add in-mold decorating (IMD) to its manufacturing portfolio. IMD is fast replacing traditional postmold painting, printing, and chrome plating. But the potentially troublesome technique takes more setup and tuning than traditional molding.
Software from Moldflow Corp., Framingham, Mass. (moldflow.com), helps molding engineers with such tasks as placing gates and designing runners and cooling lines. "It also shows the difference in flow patterns and molding with and without the in-mold decoration," says OEM/Erie process engineer Mike McCullough. "IMD needs special attention to tool design and process control, especially for thermoforming and trimming," he adds.
McCullough estimates his company saves about $7,500/mold using the simulation software. "Savings come from reduced prototype time to get good parts, optimizing gate locations early in the design, accurately predicting cooling patterns, eliminating mold retooling and freight costs, and material savings from fewer defects," he says.
Keeping trial times to a minimum means molders needn't "break the rules" by compromising process variables. "The software predicts thermal effects of the in-mold decoration material quite well," says McCullough.