Metal Finishing

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. 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:

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. 1. 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)
• Economical 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. 1. 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.