How many types of Surface Treatment for investment castings?
Surface treatment is a process of forming a coating on the surface of a workpiece by a certain method. The purpose is to make the surface of the product beautiful and anti-corrosive. Generally speaking, there are no special requirements for the surface treatment of precision castings. The investment castings can be rust-proof only by applying anti-rust oil. However, in order to improve the appearance quality, protect the surface from external influences, change material properties and brand influence, etc., we will do a casting surface finishing.
Surface treatment methods can be summarized in the following common methods:
1. Powder coating: Better surface coating way than color paiting, which is good at environment protection and harmless to workers.
2. Hot dip galvanizing.
This is accomplished by immersing the carbon steel component in a plating bath of molten zinc at a temperature of about 510 °C. The result is that the iron-zinc alloy on the surface of the steel piece gradually becomes passivated zinc on the outer surface of the product. Hot dip aluminizing is a similar process.
3, Plating Electroplating.
Immersion of the electroplated parts in an aqueous solution containing the deposited metal compound. The plating solution is allowed to flow through the plating solution to deposit and deposit on the component. General electroplating includes galvanizing, copper, nickel, chromium, copper-nickel alloy, and the like. Sometimes phosphating is also included.
4. Paint Finishing.
Including various coatings such as hand coating, electrostatic coating, electrophoretic coating. Can be operated according to sample or color number. Secondly used surface treatment method for castings. Mainly used as the surface treatment for steel castings and iron castings.
Suitable for small type of investment castings for its high cost.
6.Pickling and Passivation:
Used to protect castings from corrosion and add a protective layer. Specialized for stainless steel castings.
7. Black oxide.
More cost-effective way to prevent investment castings from rusting than painting.
8. Surface hardening.
The surface hardening method refers to a treatment in which the surface layer of the part is hardened by an appropriate method. the core portion of the part still has strong toughness. By this treatment, the wear resistance and fatigue resistance of the parts can be improved. Since the core of the part still has good toughness and strength, it has a good resistance to impact loads. Commonly used surface hardening methods mainly include carburizing, nitriding, hard anodizing, chrome plating, surface hardening, and metal infiltration.
Stainless steel electropolishing treatment: high surface light and fast light. It can also be treated with stainless steel passivation solution. Since the casting is prone to rust, the rust prevention performance can be greatly improved after passivation.
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