Influence of Mold Coating Wear on Heat Transfer Coefficient in Aluminum Permanent Molds

Roorda, Sean C.

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Influence of Mold Coating Wear on Heat Transfer Coefficient in Aluminum Permanent Molds

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This study investigates the relationship between mold coating wear and geometry to heat transfer coefficient (HTC) in permanent mold castings. Mold temperatures were measured using inserted thermocouples and inserted fiber optics using two different test molds. Mold temperatures were simulated by altering the heat transfer coefficient utilizing commercial solidification software. The results showed a uniform HTC was not accurate enough to simulate temperatures. Simulation of convex tooling surfaces required higher HTC as compared to concave surfaces. As mold coating wore in use, mold temperatures increased. Fiber optics were proven to be a feasible method to measure temperatures in permanent molds. In conclusion, mold coating wear and tooling geometry have major impact on HTC; changes to HTC due to air gap formation requires a multiple step heat transfer coefficient for accurate simulation. The operating HTC in permanent mold castings that were the focus of this study is a variable that changes with time from the onset of solidification, as well as with coating thickness deposited on the mold surface. Utilizing a HTC function that varies with time in the solidification software resulted in fidelity with the industrial data generated from the plant.

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