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Process Selection - From Design to Manufacture Part 4

Tham khảo tài liệu 'process selection - from design to manufacture part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Plaster mold casting 59 1.8CC Plaster mold casting process capability chart. 60 Selecting candidate processes 1.9 Squeeze casting Process description Combination of casting and forging. Molten metal fills a preheated mold from the bottom and during solidification the top half of the mold applies a high pressure to compress the material into the final desired shape. Also known as liquid metal forging and load pressure casting see 1.9F . 1.9F Squeeze casting process. Materials Typically non-ferrous metals but occasionally ferrous alloys. Process variations Pouring can be performed automatically. Economic considerations Production rates low due to mold filling for minimum turbulence. Long setup times. Lead time moderate to high. Material utilization excellent. Near-net shape achieved. High degree of automation possible. Economically viable for production volumes of 10000 . Tooling costs high. Equipment costs high. Squeeze casting 61 Direct labor costs low to moderate. Finishing costs very low. Used to minimize or eliminate secondary processing. Typical applications Aerospace components Suspension parts Steering elements Brake components Design aspects Complex geometries possible. Retractable and disposable cores used to create complex internal features. Large variations in cross section possible. Undercuts bosses holes and inserts possible. Placing of parting line important i.e. avoid placement across critical dimensions. Machining allowances usually in the range 0.6-1.2mm. Draft angle ranging 0.1-3 depending on section depth. Maximum section 200 mm. Minimum section 6 mm. Minimum dimension 020 mm. Sizes ranging 25g-4.5kg in weight. Quality issues Low porosity experienced. Low speed mold filling minimizes splashing. Accurate metering of molten metal required to flashing. Excellent mechanical properties can be obtained similar to forging. Adequate process control important i.e. metering of molten metal pressures solidification times etc. Graphite releasing agent and .