Metal Finishing

Metal Finishing is more than meets the eye

Our work doesn’t end with the casting or fabrication processes. The post-treatment and finishing processes can also have a huge impact on your final product. Whether it is for functional or cosmetic purposes, there is still much more to be done.

Omnidex provides a wide range of surface finishing solutions. The following is an overview on the most popular surface finishing processes we offer. (We also offer processes beyond the scope of this list. Please consult our Sales Department for more details.)

  1. Grinding
    Grinding refers to the process of smoothing out a substrate’s surface with tools or machines. Depending on the requirement of the product, different levels of smoothness can be achieved. Substrate are sometimes ground down to reach the required functional dimensions. It is also common for parts to undergo grinding and other pre-treatment before surface coating or anodizing.
  2. Polishing
    Polishing refers to the cleaning and smoothing of the surfaces of a substrate, to achieve a glossy, decorative finishing. Often metal substrates are polished before electroplating or coating to achieve finer finishing.
  3. Tumbling
    Tumbling, also known as barrel polishing, is mainly employed as a deburring process. A matt to glossy finishing can be achieved, depending on the polishing medium applied.

Anodizing is an electrolytic passivation process used to increase the thickness of the oxide layer on the surface of metal parts. It typically utilizes sulfuric acid electrolytes, but other acids (such as chromic acid and organic acid) can also be used to produce different results. Anodized parts are often dyed or sealed to improve durability and give them the desired appearance. The process is commonly used for aluminium parts, but many other metals can also be anodized. 

The process may serve the following purposes:

    1. Improve resistance to corrosion
    2. Improve resistance to wear and abrasion
    3. Increase the surface hardness
    4. Create an electrical insulated coating
    5. Create a base coating for painting or other finishing treatment
    6. Provide decorative finishing

Our anodizing process is done in specialized workshops by highly trained operators. Different thickness and hardness of the film can be achieved base on your requirements.

Anodizing that produce coatings thicker than 25 μm (0.001 inches) and up to 150 μm (0.006 inches) are referred to as Hard Anodizing (also known as Type III anodizing in the US). The process also utilizes sulfuric acid electrolytes, but operates with lower temperatures and higher voltages to achieve a thicker and harder anodized layer.

Advantages of Hard Anodizing:

• Very durable, extremely hard surface
• Better corrosion and wear resistance 
Sealant is not necessary

Disadvantages of Hard Anodizing:

Rougher surfaces
Less appealing cosmetic properties
• A thick anodized layer may affect the functional dimensions of a part
• 
Difficult to control colour consistency within a batch

Hard Anodizing is often used on parts that require better corrosion and wear resistance but are less concerned with cosmetics. We highly recommend this process on heavy-duty industrial equipment that may be exposed to the elements. Please contact our Sales Department for more specification on our anodizing processes.

Electroplating refers to the use of an electrical current to coat an electorally conductive substrate with a thin layer of metal. The process is usually for decorative purposes, but in some cases, it can also improve electrical conductivity (for gold and silver plating). Common electroplating process include:

Chrome Plating
Copper Plating
Gold Plating
Nickel Plating
Rhodium Plating
Silver Plating

The following materials (substrates) can undergo electroplating processes to create decorative metal coatings:

Ferrous

Non-Ferrous

Cast Iron
Stainless Steel & Stainless Steel Alloys
High-Carbon Steel
High Speed Steel
Mild Steel
High Tensile Steel

 

Aluminum and Aluminum Alloys
Copper, Copper Alloys & Beryllium Copper
Lead
• 
Nickel and Nickel Alloys
Tin
Titanium
Zinc

Electroless plating does not require the use of an electric current, instead it uses an autocatalytic chemical reaction to deposit a thin plating layer onto the substrate. This process can also be applied to non-conductive materials such as plastics. The most common form of electroless plating is electroless nickel plating, with forms an even layer of nickel-phosphorus or nickel-boron alloy on the substrate, offering the following characteristics:

Resistance to corrosion
Resistance to wear
Resistance to abrasion
Improved ductility
Better soldering abilities
Lubricity

Powder coating refers to the process in which a free-flowing, dry powder is typically thermostatically applied, followed by curing under heat. Our powder coating workshop offers the following powder coating methods:

      1. Electrostatic Gun (Corona Gun)
      2. Tribo Gun
      3. Fluidized Bed Method

This process offers numerous benefits over typical wet paint, including:

Uniform film thickness
Improved resistance to corrosion and UV
Longer lifespan
Parts coated using powder can be bent without
cracking the coating

It also offers many financial and environmental benefits:

• Unused powder can be recycled, reducing waste
• No need to use evaporate solvents
• 
Reduced fire, health and safety hazards
• 
Curing process is faster and requires less energy

Conventional spray painting refers to the process of applying a liquid paint to a substrate. The process usually utilizes a spray gun or pressurized pump to apply an even layer of liquid paint.
This painting process offers several benefits:

• Can be used on products which cannot be heated
• 
Highly customisable, offers a wide range of colour options
• 
Can achieve very thin layer of paint (15-20μm)
• E
conomical process, suitable for smaller productions

It should be noted that spray painting does have its own limitations. Liquid paint is generally not as durable as powder coating or anodizing, often requiring maintenance and re-finishing down the road. It is also tricky to get a perfectly even finish. 

Omnidex has a series of QA and QC processes to ensure all spray-painted products are up to the highest standards. We partner with highly experienced workshops in the region to offer a diverse range of spray painting solutions. 

Physical Vapor Deposition (PVD) is a plasma coating deposition process that can deposit a thin film on a substrate, effectively coating it with a vaporized form of the desired coating material.
Common PVD methods include:

      1. Sputter Deposition
      2. Evaporative Deposition
      3. Cathodic Arc Deposition
      4. Pulsed Laser Deposition
      5. Electron Beam Physical Vapor Deposition

 PVD coatings offer the following advantages:

• Improved resistance to wear
Create a coating that will not chip, corrode, tarnish or fade
Superior hardness
Plenty of metallic colour options
More environmentally friendly

PVD can be used on stainless steel and titanium. Other materials such as aluminium, brass, zinc, carbon steel and brass are usually chrome plated before PVD coated.

The PVD coating process is often used for automotive parts, domestic appliances, bathroom and kitchen fittings, as well as nautical and architectural hardware.

Please note that each surface finishing process has its own advantages and limitations, and sometimes several finishing processes can be combined to produce the best results. It is always a good idea to discuss your project with our professional engineering team before making your decision. Feel free to contact us anytime. You may also check out the full-range manufacturing services we offer. 

Take a Closer Look

We are always ready to help you with your latest project.

Contact our Customer Service and let us know how we can help to catapult your next project to success.

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   +86 20 8388 7080
   UK: +44 (0)808 123 0080
   USA/Canada:  + 1 (800) 967 2110

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