Sand Casting vs. Investment Casting

1. Raw Materials

a) Sand casting raw materials are clay sand or chemical self-hardening sand, the resources of the casting sand is rich and the price is cheap.

b) The investment casting raw material was to join the polyethylene material of paraffin wax, sodium silicate, silicon sol, whose costs are higher than foundry sand.

2. Material Recycling

a） After appropriate processing, the clay wet sand and chemical self-hardening sand can be recycled, and the treatment process is simple, and its cost is low.

b） The investment casting mold material can be recycled, but the performance of the mold material will go bad, fragility increases, ash content increased, decreased mobility, increased shrinkage, color from white to brown, high processing cost and trouble.

3. Casting cycle

a） The effective efficiency of the manual sand casting and resin sand is low, but if you are using mechanical moulding equipments or automatic moulding line, the moulding cycle is short and has high efficiency.

b） The mold process of the investment casting is cumbersome, and needs relatively long period.

4. Moulding material use time

a） Moulding sand can be used for a long time.

b） The materials of the investment casting include wax, natural resin and plastic preparation, the mold materials are easy to be cooling or melting, so can't be stored in long time.

5. Casting appearance quality

a） The surface finish of the investment casting is higher than the general casting, usually ranging from Ra.3.2 ~ 12.5μm.

b） The surface of the sand casting is easy to be caused by the sand inclusion, sand wash, clip sand, air hole and other casting defects.

6. Dimensional tolerance

a） Investment castings have very high dimensional tolerance, normally could reach CT 4-6. This process could produce very complex castings, and their min. wall thickness could reach 0.3mm.

b） Because of the characters of sand moulds, so sand castings have lower dimensional tolerance, size accuracy for CT10 ~ 13, the wall thickness of sand castings is minimum of 3 to 5 mm.

7. Batch production

a） The investment casting technology can ensure the consistency of the castings.

b） Unless by using moulding machines, automatic moulding lines or shell molding process, otherwise, sand casting process is difficult to ensure the consistency of the castings.

8. Production range

a） In China, the investment casting is generally used to produce the steel castings. It is generally used to product small castings with unit weight under 20 kgs.

b） Sand casting can be used for the production of cast iron and steel castings, and cast aluminum parts. The adaptability of the sand casting is very broad, small, large, simple, complex, single, large quantities can also be adopted.

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