Nov_Dec_AMP_Digital

iTSSe TSS 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 | N O V E M B E R / D E C E M B E R 2 0 1 7 3 5 iTSSe TSS REASON TO CONSIDER RESTORATION Precision gauges and fixtures used to dimensionally check automotive components are typicallymade of heat-sen- sitive aluminum alloys using a variety of subtractive and/ or additive manufacturing techniques. Due to the required precision, machining and finishing costs are often very high, and consequently any machining mistake can become cost prohibitive. In addition, recurrent use of the tool leads to un- avoidablewear and tear, which eventually renders the tool un- acceptable for the job, even though theremay be considerable value remaining. ISSUES Aluminum alloys used to fabricate these components are specially heat treated. These materials are intrinsical- ly sensitive to any process or procedure, such as welding or conventional thermal spray, which create a heat affected zone (HAZ) on the substrate. Not only would thematerial properties in theHAZbecome substandard, but thedimensional accuracy of the tool would be compromised due to thermal distortion. OPTION Supersonic spray technology (SST) cold spray enables metal consolidation that candimensionally restore these tools with minimal or no thermal effects. Therefore, SST manual and robotic cold spray technology, which is operated at low pressures and temperatures, has become a reliable and effec- tive tool in the industry (Fig. 3). SST COLD SPRAY TECHNOLOGY RESTORES HIGH-VALUE PRECISION GAUGING FIXTURES Fig. 1 — Subtractive machining of a geometrically complex aluminum gauging tool for checking automobile polymeric shapes. Fig. 2 — Finished check fixture for dimensionally validating a plastic front bumper. Fig. 3 — Commercial SST cold spray system. Courtesy of CenterLine Windsor Ltd. Cold spray is a solid-state metal consolidation process that uses a high-speed gas jet to propel metal and other pow- der particles against a substrate where particles plastically deform and consolidate upon impact. The term cold spray re- fers to the relatively low temperature involved in the process, which is typically much lower than the melting point of the spraymaterial and substrate. In the SST cold spray equipment, air can be used as a propellant gas and temperatures will be lowenough not to thermally disturb the substratematerial. Af- ter low-temperature dimensional restoration of the area, the newly consolidatedmaterial can be effectivelymachined back to tolerance using standardmachining techniques. BENEFITS Since adhesion of the metal powder to the substrate and deposited material is achieved in the solid state, the charac- teristics of cold spray deposits are quite unique, making cold spray suitable for depositing well bonded, low porosity, ox- ide-free coatings. These attributes make cold spray uniquely 5 CASE STUDY