The process characteristics of lost mold casting are as follows:
1) High dimensional accuracy of the casting. Lost mold casting is a process that is close to no margin and precise forming. This process does not require mold taking, parting surface and sand core, so the casting has no flash, burr and mold inclination, and reduces the dimensional error caused by the combination of sand core. The surface roughness of the casting Ra is 3.2-12.5um, the size tolerance of the casting can reach DCTG7-DCTG9, and the processing allowance is up to 1.5-2mm, which can greatly reduce the cost of machining, and the machining time can be reduced by 40% to 50% compared with the traditional sand casting method.
2) Flexible design. It provides sufficient freedom for the structural design of castings, and highly complex castings can be cast through the combination of foam dies.
3) There is no sand core in traditional casting, so there will be no uneven casting wall thickness problem caused by inaccurate sand core size or inaccurate core position in traditional sand casting.
4) Clean production. There is no chemical binder in the molding sand, the foam is harmless to the environment at low temperature, and the recovery rate of the old sand is more than 95%.
5) Reduce investment and production costs. Reduce the weight of casting blank, machining allowance is small.
Lost mold casting process and other casting processes, there are its shortcomings and limitations, not all castings are suitable for the use of lost mold process to produce, to carry out specific analysis, mainly according to the following factors to consider whether to use this process:
1) casting batch. The larger the batch, the greater the economic benefit.
2) Casting material. The order of good and poor applicability is roughly, gray cast iron - non-ferrous alloy - ordinary carbon steel - ductile cast iron - low carbon steel and alloy steel.
3) Casting size. Mainly consider the scope of use of the corresponding equipment (such as shaking table, sand box).
4) Casting structure. The more complex the structure of the casting, the more it can reflect the superiority and economic benefits of the lost mold casting process. For the cases with narrow internal cavity channels and interlayers on the structure, the lost mold process needs to be tested in advance before it can be put into production.
