What Are Different Types Of Metal Finishing

The final step in the manufacturing process, metal processing and finishing, refers to various procedures used to modify the surface of metal goods and components to increase their resilience, aesthetic appeal, and environmental protection. Metal processing and finishing services also include cleaning and polishing procedures to enhance the end product's looks.

There are many different metal finishing procedures, and each has certain advantages. The type of metal processing and finishing chosen depends on the finished product's requirements and metallic composition. Metal finishing techniques are divided into adding/altering and removing/reshaping the surface.

To ensure manufacturers and businesses choose a metal finishing method that meets the needs of their metal products, let's break down each of these categories. By mastering metal finishing procedures, businesses will save time, money, and labor.

Adding And Modifying Metal Finishing Processes

Metal finishing procedures are enhanced or modified to change the surface of a component or product. A layer of the desired material is added to achieve desired features and attributes, such as better durability, aesthetics, solderability, and chemical resistance. This is rather than the metal being removed or reshaped.

The most common methods for enhancing or altering a part's surface include electroplating, electroless plating, passivation, hot blackening, and powder coating.

1. Electroplating

A metal or metal alloy is deposited on the surface of a metal part or component, known as a substrate. This is during the metal finishing process of electroplating, also known as electrodeposition. A substrate material-usually lighter and less expensive—is covered in an electroplated thin metal layer, such as copper or nickel. Manufacturers can electroplate a single metal or a mix of metals onto an object. Manufacturers often use metal layers to increase strength and conductivity. Among the materials used in electroplating are, but are not restricted to:

• Brass
• Copper
• Gold
• Iron
• Nickel
• Silver
• Titanium
• Zinc

2. ELECTROLESS PLATING

Chemical plating, also known as electroless plating or auto-catalytic plating, is a method of metal processing that uses chemicals to coat metal rather than electricity. Electroless plating comprises the deposition of metals, including nickel, silver, gold, and copper, on the surface of various materials. This is done using a reducing chemical bath. This produces a catalytic reduction of metal ions and plates the component without electrical energy. 

Electroless plating, unlike electroplating, is a chemical technique that requires no additional equipment or electrical power. Electroless plating has many technical benefits, including:

• Produces a uniform finish of the metal.
• Does not call for complex racks or jigs.
• Flexibility in plating volume and thickness.
• Achieves matte, semi-matte, and brilliant finishes.

3. PASSIVATION

Stainless steel and other metal alloys like aluminum are the main targets of the chemical process of passivation. This process is utilized as a post-treatment plating technique. It minimizes the effects of environmental elements like water or air and strengthens treated surfaces' corrosion resistance. A heavy protective metal oxide layer is deposited during the passivation process to sluggish the oxidation process. This usually does not change the material's look.

Passivation has several advantages, including but not restricted to:

• increased resistance to corrosion
• decreased maintenance
• Contamination was eliminated

4. HOT BLACKENING

A thin black oxide coating is applied to the surface of a substrate during the metal finishing process, known as hot blackening. This method is usually carried out in large batches, uses a series of tanks containing various cleaning agents, coolants, and acidic compounds, and is best suited to smaller parts.

When a protective dark coating is required, manufacturers use hot blackening to strengthen the abrasion resistance of metal parts. This is done to produce a matte black finish on automotive, military, and firearm components.

5. POWDER COATING

Powder coating is a metal finishing procedure that involves the use of a dry powder rather than a liquid to cover a metal product. Various components are mixed during the powder coating process to form a dry powder coating. These components include pigments, flow modifiers, leveling agents, and other additives. Long molecular chains and a high cross-link density are formed from the completed powder, which is then heated before being electrostatically deposited on the substrate surface.

While offering an appealing surface, powder coatings are typically more durable than liquid paints. Metal goods that have been powder coated are more resistant to coating quality degradation brought on by chemicals, moisture, UV light, and other harsh weather conditions.

6. PHOSPHATE COATING

Phosphate coating, or phosphatization, is a chemical process used to treat cast iron and other metals, including steel. It produces a thin adhesive layer that boosts corrosion resistance and offers high adherence. Iron, zinc, or manganese phosphates are often found in thin, adhesive phosphate coating layers. Notably, the phosphate coating's finish ranges from grey to black.

Phosphate coating increases corrosion protection while also extending organic coating life, offering a suitable lubricant base, and serving as a preparation for later coatings like paint or powder coating. Phosphate coatings can be used with an oil coating to improve metal parts' anti-rust and anti-galling.

Processes For Removing And Reshaping Metal Finishing

By removing or reshaping the surface of a part or product, metal finishing procedures can change the surface. This will achieve the desired finish. Several metal finishing techniques are employed when the end user desires a polished, reshaped, abrasive, or visually pleasing final metal part or product.

Various techniques can be used to remove or change its shape. However, abrasive blasting, buff polishing, and electropolishing are some of the common ones.

1. ELECTROPOLISHING

Electropolishing uses electric current to remove metal ions from metal components, often stainless steel or comparable alloys. Electropolishing has many advantages, including:

• Improves corrosion resistance.
• Cuts down on cleaning time.
• Burrs and a tiny bit of debris are removed.
• Removes the peaks and valleys.
• Polishes difficult-to-reach areas.
• In some cases, reduces the size of metal pieces.

2. BUFF POLISHING

Buff polishing is a metal finishing procedure used to clean and smooth the surface of a metal object, similar to electropolishing. The primary distinction between the two procedures is that buff polishing utilizes a machine with a cloth wheel rather than an electrochemical reaction. Manufacturers use buff polishing to give metallic parts and goods a glossy, decorative, and eye-catching surface. Metal components are also prepared for electropolishing via buff polishing. Other tools, such as power brushes, are also used for polishing, removing surface contaminants, and edge-blending metal surfaces.

3. ABRASIVE BLASTING

A stream of abrasive material is aggressively propelled against the surface of a metal object during the abrasive blasting process. This is used to finish metal. Surface finishing and cleaning are integrated, utilizing abrasive blasting to save time and money. Another way to prepare a surface is to use abrasive blasting before painting, coating, or plating.

It is significant to note that this procedure has various iterations, each utilizing various abrasives. Shot blasting employs metal shots such as aluminum oxide or carbon grit, and sandblasting, which uses sand, are the two most popular abrasive blasting techniques. Abrasive blasting has several advantages, including but not restricted to:

• Eliminates surface impurities.
• Creates a finish that is clean and aesthetically pleasing.
• Increases the surface area or modifies the form.
• The surface preparation procedure is provided before plating, painting, or coating.

How To Select Best Industrial Metal Finishing Method For Your Manufacturing Project

It cannot be easy to select the right metal finishing method. This is because there are many variables to consider, such as cost, production speed, and metal hardness. Manufacturers and companies should collaborate with skilled metal processing experts to create a personalized and economical metal finishing process. This lowers operating costs, simplifies production, and produces improved finished metal goods that surpass consumer expectations.