The surface of investment castings would be oxidized for high temperature during metal liquid pouring and solidification process.As the oxide layer is uneven and metal oxide on the casting surface would have effect on oxide in shell.Prompting uneven falling from of investment casting surface,which will obviously add the surface roughness of investment castings.
Tongda foundry has the ability and skills to deliver investment castings for oil and gas industry.We have been supplying quality investment castings to the oil and gas industry for more than 30 years.As these investment castings are used in high temperature and high working power,so they encounter hard working conditions(water,mud,crude,ect).
Lost Foam casting is, in terms of casting processes, a relatively recent innovation that exhibits characteristics of both Investment casting and Sand Casting. It is a form of evaporative pattern casting where the pattern is of foam rather than wax. The foam pattern is covered in refractory material, as in investment casting, but the ‘shell’ is then surrounded by compacted un-bonded sand to give it strength. When molten metal is poured into the shell the foam pattern vaporises on contact. The result is a process that delivers the quality and accuracy of investment casting with the lower costs and greater flexibility of sand casting.
1.A foam pattern (see images above) is made using expanded Polystyrene (2.5% Polystyrene, 97.5% air). This can be formed by closed-die moulding, machining or assembly from multiple parts. Risers and gates are included at this stage.
Shell mould casting is one technology of casting. Products are casted from thin cast shells directly. Materials include carbon steel, alloy steel, etc. can all be casted in shell mould casting process.
Both cast iron and cast steel are the important materials used for castings in china. But the castablility of cast iron is better than cast steel. There're some reasons which cause the difference.