What is Metal Finishing, and What are its Various Types?

Being a leading metal manufacturing company, Sree Metaliks Limited is here again to inform you about a crucial process in the manufacturing process. Yes, we are talking about the final step in the manufacturing process- Metal Finishing. But what are metal finishes? The manufactured product has a rough surface that needs to be given an even texture. It is what Metal Finishing helps with. It involves cleaning, deburring and descaling the metal for smooth metal finishes.

Significance of Metal Finishing

Before diving into the insights of types of metal finishing, you must know why it is important. Below are some points explaining its significance in the metal manufacturing industry.

• The metal finishing process results in increasing the durability of the final product.
• It helps enhance the electrical and chemical resistance of the metal.
• Metal finishing increases tarnish resistance and electrical conductivity.
• Stainless steel metal finishing helps enhance its decorative appeal.

Different Types of Metal Finishing

Metal Finishing is divided into various types. All these categories are explained in detail below.

Plating

One of the first types of metal finishing is plating. It typically involves bathing the metal product in a chemical bath to coat it with thin layers of other metals like chromium, cadmium, zinc and nickel. The electroplating method uses an electric current to coat the metal’s surface. On the other hand, the plating can also be electro, which uses the autocatalytic process where the substrate catalyses the chemical reaction.

The plating metal finishing process results in enhancing the corrosion resistance, durability, exterior appearance and surface friction of the metal. However, this method does not generally help in smoothing out surface defects.

Cleaning/ Brushing

Another type of metal finishing procedure is brushing or cleaning. It is the most effective process to eliminate surface imperfections. The cleaning or brushing machines create a uniform surface with a parallel grain texture. These machines help smooth out the exterior surface of the product. They have an abrasive brush or belt that creates round edges. Welding operations often lead to producing slag which is removed in this process by wire brushing. This brushing is also used for removing grit and scales before cleaning the surface.

The cleaning or brushing process also involves using chemical or acid baths to clean oil residues from forming, machining and other processes.

Buffing/ Polishing/ Honing/ Lapping

Buffing is an abrasive method used to reduce the roughness of metal surfaces after machining. Microinches unit is used to measure a surface’s roughness. Fine grinding uses wheels or mounted points to reduce the roughness of the surface to 8-16 µ-in. This process also uses abrasive powders with leather or felt wheels for polishing and buffing. Lapping and Honing processes use abrasive compounds. These compounds increase the smoothness of surfaces by rubbing.

Polishing can either be done manually or robotically. While reducing the roughness of the metal’s surface, it also enhances its lustre. Therefore, polishing is popularly used for improving a surface’s aesthetics.

Grinding

Another name for the type of metal finishing is grinding. The process is carried out using grinding machines that have abrasive wheels that smooth out surfaces. These machines aim to deliver different levels of finite smoothness. Grinding is typically used to reduce the roughness left over after machining. Surface grinder is the most common grinding machine. However, there are several other machines like blanchard grinders and centerless grinders. Blanchard grinder is mainly used for metalworking techniques as it is ideal for large parts.

The grinding process is also done using hand grinders that help with slag cleaning and metal removal. Die grinders are also used that help with detailed work.

Vibratory Finishing

Next on the list is vibratory finishing. It is used to deburr products and remove sharp edges from them. The vibratory method involves putting a part in a drum filled with abrasive pellets. The drum then undergoes tumbling vibration to create a uniform surface texture.

Blasting

Blasting is another metal finishing type. It uses blast machines like sand blasting machines. This method is typically used when a project requires a uniform matte texture. The sandblasting method forces various abrasive materials on the substrate, like metal pellets, sand and steel shots, at high speed. The resulting product of this method has a smooth and clean texture. Another blasting method is the shot peening method. It is used for enhancing fatigue resistance, fretting resistance and stress corrosion cracking resistance of a product.

Heat Treating

Next comes heat treating. After the final shape of a metal product is achieved in the manufacturing process, it undergoes heat treatment to achieve the desired characteristics. For example, several products like gears undergo this treatment for hardening. The main objective of heat treatment is to remove any residual stress that might have been left in the previous manufacturing steps.

Coating

It is one of the most inexpensive methods. It used oil-based or water-based paints to coat the metal surfaces to protect them from corrosion. The paints used in this process are available for varying applications. As for marine applications, anti-fouling paints are available. In this metal finishing process, powder coats can also be applied instead of paints. The powder coating offers similar aesthetics but greater durability.

Hot Blackening

Another type of finishing process is the hot blackening process. In this method, a layer of black oxide is applied on the product’s surface to enhance its abrasion resistance and provide it with a matte black finish. It is a high-temperature process where the product is dipped into a series of tanks that contain caustics, cleaners and coolants. Usually, hot blackening is used in the manufacturing of tools, automotive parts and firearms.

Read More: The Role of Blanking Process in Sheet Metal Fabrication: A Comprehensive Overview

Conclusion

The metal finishing process is widely used to provide a finished look to the final product in the metal manufacturing process. However, it is essential to choose the right process from the various types for desired results. That is why you must buy only from leading manufacturers like Sree Metaliks Limited. We make it our priority to deliver only high-quality products. Therefore, we choose only the most suitable metal finishing type for each product.