Tongda could provide high quality investment castings with various surface treatment requirements.Now we would like to introduce some main surface treatments.
Anti-rust is always done by investment casting foundry if there is no special requirement on casting surface.We could use anti-rust oil or anti-rust water to prevent rusting during the delivery by sea or by air.
Painting is also commonly used after shot blasting of investment castings.We could paint with different colours according to customers' drawing.One day,a customer sent us a drawing of investment castings,in the drawing marked letters"paint John Deere green before machining".For such painting,we need to paint according to customer's colour disk.Thus to ensure the painting colour is what our customer needs.
The usage of Black oxidization for investment castings is to prevent rusting also,it is more cost-effective comparing with painting.And will heating castings to certain temperature,but do not worry,it will have no effect on internal organization of parts.
Comparing with painting,powder coating has less harmness on both environment and workers.
Zinc plating is usually adopted when the length of investment castings is smaller than 300mm and the weight is no more than 0.5kg.We could also do zinc plating for larger investment castings,but the cost is high.
6.Pickling & passivation
Pickling&passivation is not for all investment castings,it is only suitable for stainless steel investment castings.
Case hardening is a way that make surface hardness to required hardness,but the hardness of internal section is still low.
Phosphating treatment is widely used pretreatment technology, a kind of chemical layer converting process. Such process are mainly used as the surface treatment for steel castings and iron castings. Sometime, they are also used for the ferrous metal castings, such as aluminum die castings or zinc castings.