September AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 1 8 2 3 The research objective was to identify permanent PVD thin film coat- ings that could be applied to the hot fac- es of the die and eliminate the need for conventional lubrication. Following ex- tensive laboratory testing at the Colora- do School of Mines [5] , an AlCrN coating was selected and applied to the entire die used to produce balance shaft hous- ings. As illustrated in Fig. 6, all surfaces of the steel die contacted by the liquid aluminum were coated, including the shot block, runners, cavity insert and chill vent on the ejector side of the die, and the runners, cavity insert, and chill block (not shown) on the cover side of the die. Plant trials demonstrate that the AlCrN coating enables a reduction of about 85% in the use of conventional organic lubricant, improves cycle time by about 12%, and improves the inter- nal quality of the die castings. The coat- ing is also expected to extend the life of the casting tool. To date, roughly 20,000 castings have been produced using the AlCrN coated tool, so details of extend- ed die life are not yet available [5] . SUMMARY Thin film cathodic arc PVD coat- ings have excellent commercial poten- tial for a number of markets, as they enable surface properties to be modi- fied and optimized independent of the material’s bulk performance. Howev- er, many cathodic arc processes suf- fer from the presence of defects within the coating thickness, limiting com- mercial application. The arc plasma acceleration process reduces the size and number of macroparticles and other defects in the coating. This pro- cess should open up new applica- tions and markets for PVD coatings, including corrosion protection, wear resistance, reduction of die lubrica- tion, and life extension of forming tools. ~AM&P For more information: David Bell is president and CEO of Phygen Coatings Inc., 1400 Marshall St. NE, Minneapolis, MN 55413 , 612.331.4224, tech@phygen.com , www. phygen.com. References 1. V.N. Khominich, Arc Plasma Acceleration: A Me- thod for Improving Coat- ing Quality by Decreasing Macro Particle Inclusions, 37th ICMCTF, San Diego, 2010. 2. C.P. Mulligan, et al., CrN, CrN/SiC and CrN/DLC Coatings Deposited by a Novel Plasma Accelera- tion Process: Processing and Properties, Matls. and Manufac. Proc., 29, p 1037- 1043, 2014. 3. General Motors Engi- neering Standard 9540P, General Motors Corp., Detroit, 1997. 4. Z. Gay, et al., Study of Structural Aluminum Casting Operations Using CertiPhy Plus Coatings, Paper No. T14-061, NADCA 2014 Congress. 5. B. Wang, et al., Results froma Series of Plant Trials to Evaluate the Impact of PVD Processed AlCrN Thin-Film Die Coatings to Minimize Die Lubrication, Paper number T17-083, NADCA 2017 Congress. Fig. 5 — Steel slide inserts used in the production of a die cast driveshaft housing after 1256 shots [4] . The upper core with a 5-µm thick AlCrN coating shows no soldering, while the lower uncoated insert shows soldering. Fig. 6 — 3Dmodels of die cast balance shaft housing die: (left) ejector side and (right) cover side. An AlCrN coating applied to the entire die reduced the need for lubricant and improved both production cycle time and die casting quality.