Products often have an unfinished or suboptimal surface after the initial production and metal forming steps. Therefore, they need to be treated for subsequent production steps and to obtain the desired finished surface.
A wide range of surface processes are used in manufacturing to improve part surfaces. They can add material layers to a surface (e.g., corrosion-resistant coating), remove undesired materials from a surface (e.g., sandblasting), reshape a surface (e.g., deburring or shotblasting), or modify the properties of a surface (e.g., hardening).
In this article, we’ll go over different types of surface processes and technologies to learn which one is good for what application.
Laser Material Processing
Lasers modify part surfaces using a focused beam of light, called the laser beam. Different types of lasers are used in manufacturing to process metals, plastics, and other types of materials. Laserax’s fiber lasers, for example, are used to clean, texture, weld, and mark metal surfaces.
Other lasers on the market can also be used for laser cutting, laser hardening, and laser cladding.
Manufacturers choose lasers for several reasons:
- No consumables: Operating without consumables, fiber lasers are among the most popular types of industrial lasers. They can replace technologies that rely heavily on consumables, such as abrasive blasting, inkjet printing, and chemical cleaning.
- Fast processing: A laser’s power can be scaled to meet the needs of production lines. For example, of 100W laser can process parts almost twice as fast as a 50W laser. An excellent way to address bottlenecks.
- Easy automation: Lasers are simple to automate because they are computer-driven and include few mechanical components.
- Low operating costs: While they require a high initial investment, lasers have very low operating costs (no consumables, low power consumption, no operators needed, etc.). This offers a substantial return on investment in high-volume productions.
- Precise treatments: Lasers can be used to process very precise areas. This allows many manufacturers to eliminate masking and save time.
- High reliability: Lasers have little or no moving parts, minimizing failures caused by mechanical wear. This makes them more reliable than most technologies on the market.
1. Laser Cleaning
Laser cleaning is used to remove contaminants from substrates, preparing them for subsequent manufacturing steps like painting and welding. Common processes include laser coating removal and laser oxide removal.
2. Laser Texturing
Laser texturing modifies the texture of metal surfaces by etching linear (or other) patterns into them. This improves adhesion for other applications like adhesive bonding and thermal spray coating.
You can see the effect on the surface in the following pictures, which include a cross-section view of a laser textured surface (first image) as well as a scanning electron microscope (SEM) view of the surface (second image).
3. Laser Marking
Laser marking, also known as laser etching, laser engraving, or laser annealing, is the process of creating permanent markings on a part’s surfaces. The process can be adapted for various surface types, such as aluminum, stainless steel, and die-cast steel. It is mostly used to create high-quality, high-contrast identifiers for traceability. It is also used to engrave logos.
4. Laser Welding
Laser welding is used to join metal surfaces together by melting them. The process has a low heat-affected zone and is increasingly used for precise applications like battery tab welding, replacing slower methods like ultrasonic wire bonding.
Coating Surface Treatments
Surfaces processes include many coating treatments that add a layer of material to provide surface properties like corrosion resistance, wear resistance, and improved electrical conductivity. Surface coatings are also often used as a surface finishing process to improve parts’ aesthetic.
These treatments often require that the surface be cleaned and roughened beforehand. Surface pretreatments like laser cleaning, sandblasting, and chemical cleaning are typically used prior to coating.
Electroplating, commonly known as e-coating, is widely used in the automotive industry to improve corrosion-resistance for car parts exposed to corrosive agents. The parts are immersed in a chemical bath, where the coating adheres to the surface through an electro-chemical reaction.
Anodizing is a coating process used to improve wear and corrosion-resistance. The process generates a natural oxide layer on the surface of metal parts. An aluminum substrate for example, will generate an aluminum-oxide layer.
3. Thermal Spray Coating
Thermal spray coating uses a blow torch to melt a powder or wire feedstock which adheres to the surface. Various thermal spraying processes exist and can grant a wide variety of properties, such as thermal resistance, environmental protection, and electrical conductivity.
4. Powder Coating
Powder coating uses a dry powder instead of the typical liquid paint. It is used in many industries to achieve a surface finish that is tougher than traditional paint, especially on metal surfaces.
Chemical Surface Preparation
Chemicals can modify metal surfaces through chemical processes and are used to prepare surfaces for subsequent production steps.
Chemical treatments are very effective, but they usually come with downsides, such as:
- Wastewater management and chemical disposal
- High cost of chemicals
- Safety issues and personal protective equipment (PPE)
- High power consumption due to chemical bath heating
- Equipment wear caused by dripping of chemicals onto production equipment
1. Chemical Cleaning
Chemicals can be used to remove contaminants from surfaces, making sure they are perfectly clean before subsequent manufacturing steps like painting, coating, and welding. Different chemical cleaning methods include chemical baths, chemical brushes, and manual degreasing with acetone.
2. Chemical Etching
Chemicals can be used to etch metal surfaces, creating random patterns that improve adhesion before subsequent processes. Surfaces can be sprayed with chemicals that slowly etch the metal, then the chemicals can be cleaned off. Parts can also be immersed in a chemical bath and cleaned off afterwards.
Mechanical treatments are among the most widely known surface treatments. They provide the speed needed to process large surfaces quickly and often come at a low initial investment.
However, they involve high recurring costs and lack precision, requiring masking to protect specific areas.
1. Abrasive and Non-Abrasive Blasting
Blasting treatments include processes that shoot media at a surface to remove contaminants and alter the surface texture. They are widely used to prepare large surfaces for coating.
The most widely known abrasive blasting process is sandblasting, but there are non-abrasive processes like dry ice blasting as well. Abrasive blasting is ideal to clean and texture surfaces at the same time, while non-abrasive blasting is ideal to process more sensitive components.
2. Mechanical Brushes
Mechanical brushes are rotating brushes that are great at removing thick oxide layers. They can also be used to remove burrs, making them an excellent post-treatment for cutting applications.
We hope this article helped you get a grasp of the different surface processing methods.
As a laser manufacturer, we can help you figure out if laser technology is a good choice for your application, whether you have laser marking, cleaning, texturing, or welding needs.