Removing surface contaminants is an essential step that directly impacts the performance and durability of materials and components.
Understanding surface contamination helps compare standard decontamination methods and how laser technology differentiates from traditional approaches.
Surface contamination is the presence of unwanted substances on a material’s surface. These contaminants can appear as thin films or particles and come from various (predictable or accidental) sources, including manufacturing processes, environmental exposure, or handling.
Their presence can negatively impact further processes, such as painting, coating, welding, or bonding, and compromise product quality and performance.
Common types of contaminants include:
The removal of surface contaminants helps ensure clean surfaces for optimal adhesive bonding. By removing impurities such as oils and dust, we maximize the surface energy available for adhesive bonding, resulting in high-quality bonds.
Also, parts or materials that have been previously painted or coated (e.g., for corrosion protection) may require a new coating or paint. In such cases, removing the old layer beforehand is crucial to ensure its proper adhesion.
Decontamination can also protect substrates against corrosion, oxidation and other degradations.
Removing contaminants prevents premature wear and tear and extends a material’s or part's lifespan. This process is fundamental for coating and bonding applications to ensure maximum durability.
When it comes to welding, maintaining a clean surface prevents weld contamination, resulting in weak joints due to poor fusion, cracks and failures due to porosity, and low-strength welds.
Dust, corrosion, oils and other contaminants can affect a substrate’s performance and the efficiency of components or moving parts.
The removal of contaminants optimizes these components’ performance, efficiency and overall quality.
For example, it can ensure peak conductivity for solar panels and EV batteries, or maximize the adhesiveness and thermal transfer of aerospace-related parts.
Bonding failures can occur if contamination issues aren’t identified and eliminated. Such failures can have a dramatic impact on your scrap and rework rates.
For example, cleaning a battery cell’s surface before wire bonding (connecting busbars and cells) ensures high-quality, defect-free bonds without damaging the battery components.
Preventing contaminated surfaces can also lead to considerable cost savings, especially in large-volume productions.
In this section, you will find various cleaning methods used for the removal of surface contaminants.
When it comes to choosing among the available methods, the following questions must be part of the equation:
The figure below illustrates the typical decision-making process:
Each of the following methods is compatible with one or more materials, substrates, and contaminants. Although they are all relatively safe, some require more protective measures to prevent health and safety hazards.
This cleaning technique utilizes solvents to dissolve tough oils, greases, paints, adhesives and other organic contaminants on various surfaces (e.g., metal, ceramics, glass, plastic).
Despite its effectiveness, precision and fast evaporation, solvent cleaning poses health and safety concerns. The solvents used are also closely regulated for their potentially harmful environmental impact.
Mechanical cleaning regroups abrasive-based cleaning techniques such as sandblasting, bead blasting, wheel blasting, grit blasting and wire brushing. Some non-abrasive cleaning processes, like dry ice blasting, are also included in this category.
These fast, low-cost methods can remove most contaminants on large surfaces. However, mechanical abrasives generate dust that can recontaminate surfaces. For this reason, a degreasing step is often necessary after mechanical cleaning. Such techniques also require high maintenance and offer relatively low precision.
This cleaning method involves a wide range of alkaline and acid solutions (e.g., ammonium carbonate-EDTA, phosphoric acid, boric sulfuric acid). Chemical sterilization is achieved either through manual application, immersion or spraying.
Chemical cleaning is precise and can improve adhesion and roughness by modifying a surface’s chemical structure. However, such processes typically take more time, generate waste, and pose safety and environmental concerns.
This approach is based on natural, nonpathogenic microorganisms and their appetite for hydrocarbons. Microbial cleaning is often considered for electronic and optical components.
Microbial cleaning offers a safe and eco-friendly way to decontaminate surfaces by breaking down and digesting carbon-based contaminants (oil and grease). The generated byproduct simply consists of soluble fatty acids, carbon dioxide and water.
This approach is less expensive than solvent cleaning but also less precise.
Plasma consists of an ionized gas like oxygen or argon, which is heated and projected onto a material’s surface (e.g., aluminum, glass, plastics, polymers, ceramics).
Plasma cleaning is a standard, non-contact surface cleaning process that can break down and remove oil, paint and dust. Decontamination through plasma volatilization is particularly effective on optical surfaces and medical devices.
Because of its environmental friendliness and cost-effectiveness, plasma cleaning has been a method of choice for surface decontamination. However, it offers less control than laser processes, is less compatible with magnesium, zinc and copper, and can also generate carbonized residues.
Cleaning materials with laser is an increasingly popular non-contact method because of its high precision and absence of consumables.
Laser cleaning works by heating the material’s surface to ablate contaminants after they reach their ablation threshold.
By projecting pulsed laser beams on metal (and some non-metallic) surfaces, you can remove coatings, paints, oxides and rust without damaging the underlying substrate.
This process is particularly useful prior to welding.
Similarly, laser texturing modifies a surface’s texture (with micro-scale or nano-scale precision) and chemical composition. This surface treatment method has many benefits for battery manufacturing applications, such as bonding and thermal transfer.
Laser texturing not only cleans the material’s surface but also enhances its roughness. If necessary, it can also increase adhesion by applying a beneficial surface oxide layer.
One good laser texturing application example is the surface treatment of fuel cell bipolar plates before thermal spray coating. This process can successfully replace mechanical cleaning, as demonstrated in this video:
These processes are less suitable for thick coatings, clear coats or mill scale and often require a high initial investment. Still, they generate high ROIs in high-volume production lines.
Laser cleaning and texturing are surface treatment methods used in an ever-growing number of industries and applications because of their many benefits:
By integrating laser cleaning solutions into your manufacturing process, you can achieve superior surface cleanliness, discard chemicals, and enhance the overall quality and durability of your materials and parts.
Catherine holds a bachelor’s degree in Engineering Physics and a master's degree in Physics. She completed her master’s in partnership with Laserax to develop industrial solutions for the laser texturing of metallic surfaces. She is now the Applications Lab Supervisor at Laserax, where she oversees the team that tests and optimizes laser processes for clients.
When bonding, coating, painting, printing or sealing, most manufacturers eventually experience adhesion failure, corrosion protection issues, or structural weaknesses. In this article, we will explain what surface treatment is and describe its benefits for various applications. We will also guide you in choosing among today’s 10 most common surface treatment methods.
Laser surface treatments can be used on almost all types of metals, including carbon steel, cast iron, aluminum, molybdenum, and magnesium. They can remove contaminants and coatings (laser cleaning), modify the surface roughness (laser texturing), harden surfaces (laser hardening), and add materials to surfaces to improve surface properties (laser cladding).
Laser ablation occurs when a laser beam removes material from a localized area. Used in various industrial applications, this process can create permanent marks (laser marking), remove contaminants and coatings from surfaces (laser cleaning), modify a part’s roughness (laser texturing), cut through a surface (laser cutting) and much more.
