Te Cast in North America sessions of CastExpo delved into metalcasting topics of interest to casting design- ers and buyers, offering overviews of casting alloys and processes, as well as specific designing tips, methods for en- suring a strong chain of casting supply, and examples of advancing production methods for shorter leadtimes. Fol- lowing are summaries of a few of the sessions presented in St. Louis.
Discussion on Casting Alloy Applications and Properties—Aluminum and Copper-Base
Geary Smith, vice president, Manu-
facturer’s Brass & Aluminum Foundry, Blue Island, Ill., presented an overview of cast aluminum and copper alloys, including casting processes, markets, applications and characteristics. According to Smith, major growth
markets for aluminum alloys include automobiles, high strength aerospace components, and low temperature tur- bine applications. Aluminum features: • Good as-cast surface finish • Good fluidity • Low melting point • Lower density • Fast heat exchange • Reduced machining requirements • Fewer capital requirements than wrought products
• Ability to be metallurgically or me- chanically bonded as bimetal parts. Copper-base castings’ stable mar-
kets include plumbing products, ship propellers, bushings and electrical com- ponents. Te alloy’s favorable charac- teristics include: • Good corrosion resistance • Wide range of mechanical properties • Termal and electrical conductivity • Bio-fouling resistance • Low friction and wear rates • Good machinability • Potential for comparable costs • Antimicrobial properties.
The PPAP Process Data and Submissions
Are your casting suppliers ready to
go into production when they say they are? Some casting purchasers require their suppliers to go through the pro- duction part approval process (PPAP). Tree presenters (Timothy Hartigan, St. Paul Brass & Aluminum Foundry, St. Paul, Minn., Scott Gledhill, Wau- paca Foundry Inc., Waupaca, Wis., and Ron Helgeson and Doug Hepner, Cat- erpillar Inc., Mapleton, Ill.) discussed their experiences with PPAP in a panel at Cast in North America. According to Helgeson, PPAP should have three core reviewers, a design engineer, quality manager and manufacturing engineer. Te design
engineer should evaluate whether the part is defined correctly, the DFMEA is current and complete, critical character- istics are appropriately defined and key elements can be traced through to the control plan. Quality personnel should evaluate sample inspection and mea- surement correlation, the completion of lab tests and analysis, and the inspec- tion plan, and review the control plan. Te manufacturing engineer is respon- sible for making sure all the elements of the PPAP are complete and reviewed.
Patternmaking Rapid parts with less than two-
week leadtimes for fully machined cast parts are made possible through creative, advanced patternmaking. Mark Petersen, Central Pattern Co., St. Louis, Mo., provided case studies of rapid cast parts that showcase the balance of tooling design against lead time, cost and part quantity. In one case study of a ductile iron
valve body, a matchplate pattern with a two-cavity corebox was produced in CNC machined urethane. Part dime- nions were 70 x 120 x 130 mm. Te pattern was complete in five days, and initial castings were complete in two days. Te machined part to inspection took two days for 20 castings complete in two weeks. A second pattern was added to the matchplate to increase casting output, and four sets of design changes were made during production.
The automobile industry is a growth market of aluminum castings. 44 | METAL CASTING DESIGN & PURCHASING | May/Jun 2013
More than 120 pieces of this ductile iron valve body were produced and fully ma- chined in four weeks.
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