Reliability on Piston Design for Engine and Productivity Requirements

Engine manufacturers are placing stricter reliability and cost requirements on component suppliers. Manufacturers must meet growing customer expectation of higher engine performance without increasing cost or compromising in-house goals such as weight, noise, structural resistance and wear. Current design trends are to develop alternative strategies based on Predictive Engineering where design solutions and optimizations are achieved. Nevertheless, it is desirable that resulting design concepts be in accordance with manufacturability requirements for high productivity without compromising product structural integrity. Piston casting inside geometry may be of multiple or single piece center core construction. These options provide design and manufacturing advantages over each other. Single piece center cores present advantages such as smooth skirt wall thickness variation, elimination of potential casting defects on the under crown area by mold partition lines, reduction of dimensional and weight variations, and reduction of cost on mould construction and maintenance. Typical center core designs present weight disadvantages, high stress on skirt lateral zone deficiencies and low manufacturing process flexibility. This paper describes the development of a piston that accomplishes engine requirements and contributes with manufacturing productivity.