The method of the investment casting allows producing complex shaped stainless steel castings with small dimensional tolerances and excellent surface quality. The big advantage is the production of stainless steel castings from materials will probably avoid further machining operation. Using a different technology would result in high costs, or their production would be impossible.
In comparison with machining, the dimensional accuracy of stainless steel castings produced by investment casting cannot be compared, even though when compared with other methods of casting it is very accurate (CT5). Of course, even with such a perfect and precise production arise dimensional inaccuracies that occur for various reasons. The actual dimensional inaccuracies are divided into:
• Systematic – poor handling of stainless steel castings, incorrect assembly of wax model, i.e. These defects can be eliminated by following the prescribed technology more carefully.
• Random – difficult or almost impossible to remove defects. Another factor that influences the size and characteristics of the wax model and casting is deformation. It occurs especially in parts that don’t have a constant wall thickness.
The main factors affecting the dimensional accuracy of stainless steel castings:
• Volume expansion (contraction) – used materials have main influence – wax, shell material and casting material, considerable influence has as well precision of molds for wax models.
• Deformation of wax models – major influence has wax model cooling and its further processing and storage.
• Deformation of shell – the composition of layers, method of smelting wax model and firing and flushing of shells.
• Deformation of the casting itself – the shape of the casting and gating system, the shell temperature, pouring temperature and if used forms of isolation.
Of course, for some special shaped stainless steel castings, even if we pay more attention on each procedure of stainless steel casting process, it is avoidless that the stainless steel castings will get deformated after casting.
Take below bracket for example, it is very thin and long, so there is no doubt that the part will get deformed after casting.
“What I’m trying to do is work through a way to refine the design of our bracket so that you as the manufacturer can produce a quality component minimising post casting processes”–One of our customer Owen from Australia sent us a bracket for stainless steel casting. But after evaluating the structure, our engineer said that the part will have to be straightened as the overal length is quite long. In this case, it makes no sense to change the design, and only straightening can solve the deformation issue.
In conclusion, although there are lots of stainless steel foundries in China, only skilled stainless steel casting company like CFS foundry can guarantee the final quality for our customers. Looking for stainless steel casting service in China, pls get in touch with us!
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