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Te reinforcement of metals can have many


different objectives and opens up the possibility for application of these


materials in areas where weight reduction is the top priority.


• Improvement of corrosion resistance. • Increase in Young’s modulus. • Reduction of thermal elongation and engineering thermal conductivity.


Investment Casting Design Considerations


As it is with other hard alloys such as inconel or even stainless steel, the secondary machining of MMC cast- ings is a significant cost consideration. The near-net- shape advantage and the greater freedom of design that is inherent with the investment casting process provide opportunities to greatly reduce or eliminate machin- ing. The successful implementation of cast MMC can depend on possessing the necessary engineering skills to design products that take advantage of the investment casting process. For engineers, the near-net-shape advantage means


only critical surfaces need be machined. Raised pads and undercuts can be employed to relieve the surround- ing area of the part. Only minimal amounts of machine stock must be added to these machined features to assure cleanup. Investment casting also can take advantage of part


count reduction. Fig. 8 is an example of a part design that used the investment casting process to reduce the part count. This capability is particularly beneficial when designing for MMC because the fewer assembly points of a unitized structure also correlates to a reduc- tion in the cost for machining. The special properties of aluminum/silicon carbide


MMCs can be of benefit and are available to solve a myriad of design challenges for weight reduction, stiffness, vibration, heat transfer, wear and/or thermal expansion. The investment casting process offers a unique capability for the economical manufacture of MMCs.


January 2015 MODERN CASTING | 33


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