Metal plating can give component a fresh look and make them stronger, which extends their lifespans. There are several options when choosing which type of metal plating to go with to create the look and performance. There are 5 common types of plating process on machined parts, Nickel, Chrome, Zinc, Copper and Tin plating.

Nickel has good plasticity, corrosion resistance and magnetic properties, so it is mainly used in the fields of steel, nickel alloy and batteries, and is widely used in the manufacture of parts for automobiles, aircraft, and industrial machinery. After nickel plating, the parts are beautiful, clean, and not easy to rust.

Nickel plating is divided into electro-nickel plating and chemical nickel plating.

Nickel Electroplating

The nickel layer in the air is very stable, the crystallization is very small and has excellent polishing performance, the plating hardness is relatively high and can improve the wear resistance of the surface of the products, widely used in optical instrument coating, protective decorative coating, casting crystallizer electronic components.

Chemical Nickel Plating (also called Electroless Nickel Plating)

Chemical nickel plating has good thickness uniformity, and many chemical nickel plating products have better corrosion resistance and high-temperature oxidation resistance than electroless nickel plating and can be deposited on the surface of various materials without the DC motor or control equipment required for general electroplating. The heat treatment temperature is low and different corrosion resistance and wear resistance can be obtained after different holding times below 400°C. Therefore, it is especially suitable for the functional plating of parts with complex shapes and surface requirements of wear resistance and corrosion resistance. Since the process of chemical nickel plating does not require electricity, it is a simpler and more environmentally friendly choice. In the nickel plating process, the high phosphorus nickel alloy increases the strength and rust resistance of the item to which it is applied. The whole process of electroless nickel plating does not produce the six hazardous substances (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs)), which are harmful to human beings and the environment according to the EU RoHS directive.

Due to its excellent properties, chrome plating is widely used as an exterior layer and functional coating for protective and decorative plating systems.

Chrome plating forms a very thin passivated film on the surface of the part, giving it a brilliant silver finish. Chrome reduces the risk of rusting and increases the friction resistance of the surface, while chrome plating has good heat resistance and no significant change in gloss and hardness when heated below 500°C. The chrome plated layer has good chemical stability and does not act in alkali, sulfide, nitric acid and most organic acids.

In addition, in the visible range, the reflectivity of chromium is about 65%, and it can keep its reflectivity for a long time and is better than silver and nickel.

Zinc is a highly corrosion resistant metal. The rust prevention method of laying a layer of zinc metal on the surface of iron or steel insulates the iron from oxygen and water, preventing the chemical reaction necessary for rusting. Compared with other methods of rust prevention by coating iron or steel with a protective layer, galvanizing is cheaper in both initial and long-term costs. It is one of the most common methods of galvanizing.

Copper plating is the most widely used in the electroplating industry, including tin solder, lead-tin alloy, zinc die-casting parts before plating nickel, gold, silver, copper plating is used to improve the bonding force and corrosion resistance of the plating layer plays an important role.

The standard electrode of copper has positive potential, good stability, soft texture and good toughness, and is a good conductor of heat and electricity, which is widely used in industry. Copper plating can make the surface of steel with copper properties, so as to reduce the cost of products, but except for a few direct use of its electrical conductivity layer, copper plating is often used as an intermediate layer in the plating process of other metal layers. This is because the copper layer itself is easy to oxidation and discoloration, especially when it acts with the sulfide in the atmosphere, it will generate black copper sulfide corrosion products, so that the metal loses its luster.

Due to the soft texture of copper plating layer, the hardness is low, so the plating generally does not use the copper layer as the outermost layer of metal plating.

Tin plating is a coating with good solderability and certain corrosion resistance, which is widely used in electronic components and printed circuit boards. In addition to physical methods such as hot dipping and spraying, electroplating, immersion plating and chemical plating have been widely used in industry because of their simplicity and ease of use.

Tin plating gives the metal surface a silvery appearance, compared with most silver and nickel finishes, it has a gray background and can be made to have a matte or shiny finish. Since tin plating is non-toxic, it is widely used in objects that come into contact with food and drinks. For example, the parts in kitchen appliances. In addition, because tin is easy to solder and has good electrical conductivity, it is widely used in electrical and electronic products that require soldering.