Chapter26Advancedmachiningprocesses.ppt

Abrasive-Jet Machining Figure 27.17 (a) Schematic illustration of the abrasive-jet machining process. (b) Examples of parts produced through abrasive-jet machining, produced in 50-mm (2-in.) thick 304 stainless steel. Source: Courtesy of OMAX Corporation. (b) Chapter 27 Advanced Machining Processes Parts Made by Advanced Machining Processes Figure 27.1 Examples of parts produced by advanced machining processes. (a) Samples of parts produced from waterjet cutting. (b) Turbine blade, produced by plunge EDM, in a fixture to produce the holes by EDM. Source: (a) Courtesy of Omax Corporation. (b) Courtesy of Hi-TEK Mfg., Inc. (a) (b) * Chapter 27: Advanced machining processes There are situations where conventional machining processes are not satisfactory, economical, or impossible for the following reasons: Material is very hard and strong, or too brittle. Workpiece is too flexible, delicate, or difficult to fixture. Complex shapes. Surface finish and dimensional accuracy requirements. Temperature rise and residual stresses are not desirable. 27.2 Chemical machining (CM) Carried out by chemical dissolution using reagents or etchants, such as acids and alkaline solutions. engraving metals and hard stones, in deburring, and in the production of printed-circuit boards (PCB) and microelectronic devices * Chemical Milling In chemical milling, shallow cavities are produced on plates,sheets, forgings, and extrusions, generally for the overall reduction of weight The procedure for chemical milling consists of the following: if part has residual stresses from previous operations, stresses are first relieved. degrease clean surfaces to ensure adhesion of masking material and uniform material removal. apply masking material. The maskant material should not react with the chemical reagent. peel off masking that covers various regions that require etching. exposed surfaces are etched with etchants such as NaOH for Al, solutions of HCl HNO3 acids for steels, or FeCl3