WESTINGHOUSE  

Pennsylvania State University EDM Study

Executive Summary

Improvements in the machining process of four specified parts, a fingerplate, a stacked rotor plate, a thrust-runner assembly, and an impeller, used in government nuclear submarines at Westinghouse in Cheswick, PA are being explored.  The feasibility of using a wire electrical discharge machine (EDM) to replace the current chip-forming machining method is the focus of the project; expected benefits are decreased cost and improved machining time per part.

In order to justify changing from the current process to EDM, the team must perform in-depth research of the electrical discharge machining process, especially in relation to 304 stainless steel.  Using strict military standards outlined in the MIL-STD-1308-1F, the finished part acceptability must be determined.  This is currently being investigated through metallurgical testing performed by Westinghouse on a sample part, which was machined according to the specifications given in the fingerplate drawing.  Engineering Services at Penn State performed the machining with a wire EDM machine.

It is expected that Westinghouse will benefit from wire EDM implementation; once compliance to the military standards has been assured, prices obtained from a number of vendors concerning the cost of purchasing an EDM machine will be used along with the costs associated with outsourcing the machining to job shops to determine the best solution for implementation.  Thus far 17 vendors have been contacted, four of which have provided concrete dollar values of a capable machine; quoted machine prices range from approximately $130,000 to $200,000.  Due to time constraints, only eight job shops were sent a quotation letter along with the drawings released by Westinghouse.  Three positive responses have been received; however, so far no job shops are capable of machining the stacked rotor plate because of its large weight and dimensions.

At this time, a final recommendation as to the purchase of an EDM machine or the job outsourcing cannot be made because of insufficient information received from job shops.  Further investigation using the compiled list of job shops should allow for a more thorough recommendation at a later time.  

Team Westinghouse                                                                       

Aimee Ferraris - asf127@psu.edu    Brian Rawhouser - bcr118@psu.edu

Holly Hawkins - hsh112@psu.edu    Kathryn Wilner - khw105@psu.edu

Tommy Ho - txh163@psu.edu

Faculty Coach

Dr. C.O. Ruud

IE 430 - Industrial Engineering Department

*Page Completed on April 17, 2001