Large investment casting production technology

Large investment casting production technology is based on mold manufacturing, shell making, smelting and other high-level technology, as well as excellent materials and advanced equipment.Only a few things are described below.In order to produce large and complex integral precision castings, a variety of liquid injection materials, filled moulding materials, water-soluble moulding materials and plastic moulding materials have been developed.Molded materials shrink less, high strength, long-term storage is not easy to deformation, better performance.The water-soluble molding material developed in Japan is suitable for injection molding in the range of 0, 7 to 1.5MPa, and can be cast freely.At the same time, a large wax machine appeared, the maximum resultant force of 3 000 kN.For example, the v-3002 waxing machine manufactured by tem-pcraft in the United States.

In addition to improving adhesives, refractories and hulling materials, the research on coating and hulling technology has also made great progress, which lays a foundation for the production of large shells.If it is confirmed that the large-size shell should have a large rupture modulus MOE, it should not be integral and layered in structure.Therefore, the SiO content in the large-size shell binder silica sol should be high (the SiO content should reach 30 when the micelle diameter is 14 nm), polymer 5, the coating viscosity should be larger, the powder liquid ratio should be higher, and the shell drying time should be longer.There are large equipment on the equipment, such as lifting more than 1 000 kg of shell making robot.

At the same time, many new technologies have emerged in investment casting, such as gypsum casting and Rellcast CS.For example, TEC-CAST USES gypsum casting in vacuum, the minimum wall thickness of the casting is only 0.8~1.5 mm, when the casting is less than 25 mm, the dimension deviation is ±0.12 mm, the surface roughness Ra is 1.25~5.0 PTM, and the mass is 0.45~900 Kg aluminum alloy precision casting, such as aircraft fuel booster pump shell and other parts.For example, the Replicast CS method combines the advantages of lost foam, investment casting, and v-method (negative pressure modeling) to produce large precision steel castings.Integral investment casting has begun to replace some forgings, machined parts and sheet metal components with good results.For example, the jet emergency exit frame was replaced by the original 100 multicomponent and 900 fixed components.

Assembly quality from the original 8 kg to 6 kg, manufacturing cycle greatly shortened.Forks, such as Hamert's Lapott casting division, produced the PW4000 engine's ninth stage compressor guide, which replaced the original 108 casting components with integral precision casting.