tailieunhanh - Process Selection - From Design to Manufacture Episode 2 Part 1

Tham khảo tài liệu 'process selection - from design to manufacture episode 2 part 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 164 Selecting candidate processes Removal rate can be increased with the expense of a poorer surface finish. Surface detail good. Surface roughness values ranging mm Ra. Dependent on current density material being machined and rate of removal. Achievable tolerances ranging . Process capability charts have not been included. Capability is not primarily driven by characteristic dimension but by the material being processed. Electrochemical Machining ECM 165 Electrochemical Machining ECM Process description Workpiece material is removed by electrolysis. A tool usually copper -ve electrode of the desired shape is kept a fixed distance away from the electrically conductive workpiece ve electrode which is immersed in a bath containing a fast flowing electrolyte and connected to a power supply. The workpiece is then dissolved by an electrochemical reaction to the shape of the tool. The electrolyte also removes the sludge produced at the workpiece surface see . Electrochemical machining process. Materials Any electrically conductive material irrespective of material hardness commonly tool steels nickel alloys and titanium alloys. Ceramics and copper alloys are also processed occasionally. Process variations Electrochemical Grinding ECG combination of electrochemical reaction and abrasive machining of workpiece. Electrochemical drilling for the production of deep small diameter holes. Electrochemical polishing for deburring and honing. Economic considerations Production rates moderate. Material removal rates typically 50-250 mm3 s. Linear penetration rates up to mm s. 166 Selecting candidate processes Dependent on current density electrolyte and gap between tool and workpiece. High power consumption. Lead time can be several weeks. Tools are very complex. Setup times can be short. Material utilization very poor. Scrap material cannot be recycled. Disposal of sludge and chemicals used can be costly and hazardous. High degree of .