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A conformal mold cooling technology made possible by a new manufacturing technique has been developed to cool molds, especially those with lifters and/or slides that are often difficult to cool; and addresses the following major challenges in injection molding: part warpage, straight gun drilled cooling inefficiencies and the use of high cost exotic materials for challenging areas. This manufacturing process creates the serpentine cooling lines close to the part surface—helping moldmakers provide the best possible engineered molds to their customers, and thus make these customers more competitive.

This conformal cooling technology—introduced by 2008 Leadtime Leader Honorable Mention: Small Shop J.S. Die & Mold (Byron Center, MI) and The POM Group (Auburn Hills, MI)—uses POM’s Direct Metal Deposition (DMD) manufacturing process with JS Die & Mold’s mold design and manufacturing expertise.

Process Overview
According to J.S. Die & Mold President Bob Sloma, the DMD manufacturing process is the result of combining the following manufacturing technologies: laser, CAD/CAM, feedback sensors and power metallurgy. “This patented manufacturing process uses a feedback controller to enable a highly controlled deposition process to within 10 mm of net shape,” Sloma elaborates. “And, unlike laser sintered powdered metals, the process results in material with very similar mechanical and thermal properties found with wrought steel and copper alloys.

DMD is the result of blending laser, CAD, CAM, feedback sensors and powder metallurgy. It can construct cooling channels that conform to (or wrap around) the part in three dimensions, thereby bringing the coolant directly to critical hot spots. Photo courtesy of J.S. Die & Mold, POM and Great Lakes Tool & Die Collaborative.

“This technology provides flexibility and versatility in the fabrication and repair of components, such as production tooling for plastic injection molding, forging dies, die casting molds, and metal forming and metal stamping applications,” Sloma adds.

The following are advantages of the DMD process:

• The co-axial laser/powder/argon shielding gas nozzle design gives full five-axis deposition capability versus side powder feed systems, which can only deposit linearly in motion. The direct shielding of the melt pool with Argon gas allows protection of the melt pool from oxidation and eliminates the need of expensive and time-consuming inert gas chambers.
• The system has “moving optics” with the part stationary, so large-sized, heavy parts can be processed by DMD.
• The system comes with a patented closed-loop optical feedback system, which monitors and controls the melt pool height to obtain a near shape part. This also reduced post finishing operations and offers a better control of microstructure and properties of the finished part.
• The system comes with proprietary toolpath software, which translates CAD data into the nozzle motion for five-axis deposition.

Cycle Time Reduction
Sloma notes that cooling times represent the largest element of the molding cycle—with an average 44 percent of the total time involved with part cooling. “With conformal cooling lines being closer to the part and a greater amount of surface area involved with cooling using a serpentine cooling line, the part cooling portion of the cycle time can be reduced significantly,” Sloma explains. “Actual cases have seen reductions of 20 to 50 percent of the total cycle time.”