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Naperville, IL, United States

Shah J.,Product Development and Analysis PDA LLC
Metal Casting Design and Purchasing | Year: 2013

Mercury Marine provided end-user Fisker Automotive with time, weight and cost-savings over sand casting with a diecast aluminum transmission main housing. It offers higher strength to weight ratio, more rigidity, ductibility and durability, higher heat conductivity and capacity for heavy sink applications over engineered plastics. Sharp radii will cause the casting to stick to the die, making ejection difficult and leading to distortion. Using casting process simulation, die cooling and heating channels can be optimized for better thermal balance, which will assure sound castings. Smooth transitions drastically reduce the stress concentrating factor. Cored pockets of the housing lighten up heavy sections to reduce weight. Locating mounting holes as part of the main die cavity provides high precision tolerance.

Shah J.,Product Development and Analysis PDA LLC
Technical Paper - Society of Manufacturing Engineers | Year: 2014

The casting design and development process is reviewed, with emphasis on the use of casting process modeling, finite element analysis, and fatigue life prediction for design optimization. Case studies are described. Various casting alloys, processes, and rapid prototyping technologies available and their selection criterion are discussed. Recent advancements in the the cast alloy design properties as a function of the process and section thickness are presented, along with the strain life fatigue database availability for various cast iron alloys.

Shah J.,Product Development and Analysis PDA LLC | Tartaglia J.M.,Element Materials Technology
International Journal of Metalcasting | Year: 2015

This paper estimates total fatigue and transition life using strain-controlled fatigue data generated for various cast materials, using a practical example of a structural hub casting that has been in service for many years. The material data generated from recent testing, service loads and boundary conditions from the potential failure modes are entered into a finite element analysis (FEA) to predict the stress amplitudes using the same geometry that is employed for predicting the fatigue life. For the same loading, the investigators observed that the elastic modulus and specific strength have an impact on the predicted stresses. Strain-life material parameters impact the predicted strain fatigue life. At low loads (in the elastic regime), the overall exercise yields a different choice of material than at higher loads (in the elastic-plastic regime), which is driven by the strain-controlled material data properties. As an example, a sensitivity analysis was done on one alloy by varying all of its properties as well as by individually varying relevant material property data and constants. The loading and geometry were kept constant in this sensitivity analysis, to illustrate the significance of the potential error a design engineer might encounter in estimating service life. In the real world at the early design stage, various candidate cast alloys can be evaluated using this approach to achieve the desired fatigue life for the identical service loads. This methodology will yield an optimized geometry through FEA-based validations using the latest strain controlled fatigue material database for various cast alloys generated by the American Foundry Society (AFS) through sponsored research. Copyright © 2015 American Foundry Society.

Shah J.,Product Development and Analysis PDA LLC
Metal Casting Design and Purchasing | Year: 2011

Creative casting design with a better understanding of the casting process and its limitations allowed engineers at Thyssen Krupp Waupaca, Waupaca, Wisconsin, US, and John Deere work jointly to consolidate multiple castings and weldments into one auxiliary drive casting for a tractor engine. The design reduced the number of parts, eliminated inflated inventory levels, and successfully met limited space and weight restrictions. The supplier produced the part through vertically-parted green sand molding, which was a cost-effective molding process with tight dimensional accuracy and reproducibility, along with good as-cast surface finish. It is a flaskless molding process where molds are created without a metal or wood frame, which improves cycle times.

Shah J.,Product Development and Analysis PDA LLC
Metal Casting Design and Purchasing | Year: 2014

A customer approached investment casting firm Aristo-Cast Inc., Almont, Michigan, to produce magnesium prototypes for a hand-held device used in an aerospace application. The component acts as a bracket to mount some processing electronics, acts as a heat sink and is a structural member tying two halves of the housing together. The wax patterns used in the process allow little or not draft on some of the features, thereby optimizing the unit weight. Investment casting offers multiple random parting plane orientations allowing any complex features to be cast along with the main shape. The complex shapes are broken down into individual wax shapes, which can be drawn from the wax dies and assembled together. Investment casting is limited to a minimum size for holes that can be cast in.

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