By Catherine Veilleux on December 22, 2023
Laser technology offers new ways to treat metal surfaces. In this article, we discuss the advantages and disadvantages of laser technology to treat metal substrates, the two main laser surface treatments (laser cleaning and laser texturing), and conclude with some examples.
But first, what is the surface treatment of metals?
The surface treatment of metals is the process of modifying a metal surface to alter its properties. Examples of surface treatments include electroplating, anodizing, phosphate conversion coating, galvanizing, thermal spray coating, laser cleaning, and laser texturing. These treatments are used to improve surface properties like corrosion resistance, adhesion, conductivity, and wear resistance.
Laser cleaning and laser texturing are surface treatments that can be used on almost all types of metals, including carbon steel, cast iron, aluminum, molybdenum, and magnesium.
Table of Contents
- Advantages & Disadvantages of Laser Surface Treatments
- Laser Cleaning of Metals
- Laser Texturing of Metals
- Choosing Between a Single-Mode and Multimode Laser
- 7 Examples of Surface Treatments with Lasers
- 1. Texturing Batteries for Adhesive Bonding
- 2. Texturing Turbos for Thermal Spray Coating
- 3. Cleaning E-Motor Housings for Liquid Sealants (Gasketing)
- 4. Stripping Powder Coating from Hairpins Before Welding
- 5. Stripping E-Coating from Seat Brackets Before Assembly
- 6. Oxide Removal from Slip Rings to Improve Current Transfer
- 7. Electrolyte Removal from Battery Cells to Prevent Corrosion
Advantages & Disadvantages of Laser Surface Treatments
Laser technology offers a range of advantages to prepare metals for other processes. However, the technology is not adapted to all types of applications.
Here is a list of advantages and disadvantages for the laser surface treatments of metals. You can find in-depth explanations after.
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Advantages
1. Precision
We often say that lasers are precise, but how precise are they?
Laser surface treatments work by displacing a laser spot over the surface. The typical spot size at Laserax varies between 0.075 mm and 2 mm in diameter, depending on the application requirements.
With such precision, lasers can perform selective treatments, where they clean or texture specific areas and leave surrounding areas untouched. This allows many manufacturers to eliminate masking from their production process, as sensitive components and surrounding areas suffer no damage.
The high precision of the laser offers great control over the process, making it possible to achieve high quality and repeatability.
2. Easy to Automate
Laser surface treatments thrive in automated production environments.
These non-contact processes operate from a distance and never touch the surface they process. As a result, they suffer no mechanical wear and require almost no maintenance. Also, lasers require no consumables, which further minimizes the need for maintenance. This helps keep production lines running with as little downtime as possible.
3. Efficient
Lasers are one of the best tools that can be used to scale up production and eliminate inefficiencies.
For one, their speed can be adjusted as needed. One of the key parameters used to increase the speed of surface treatments is laser power. By increasing the pace at which energy is released, it is possible to scale up the speed of laser processes to meet more demanding requirements.
As non-contact processes, laser surface treatments also have almost no mechanical constraints that slows them down.
One of the few mechanical constraints comes from laser scanners. Laser scanners are ultrafast rotating mirrors used to direct the laser beam. For high power lasers, more efficient laser scanners are needed, as the mirrors need to move faster to keep up with the higher energy levels.
This mechanical constraint is typically negligible because laser experts take them into account when optimizing laser processes. They identify the most efficient pattern that minimizes the mirror’s movements when cleaning or texturing a surface.
Lasers can also perform several steps at once. In a single step, the laser can clean and texture metal components, offering complete surface preparation. This saves up time in the production process by reducing the number of steps.
4. Good Return on Investment
In high-volume production lines, laser technology can provide a quick return on investment, as operating costs are minimal—especially compared to technologies like grit blasting.
Laser surface treatments require no consumables, have a very low power consumption, can be fully automated, and cause minimal downtime.
For many manufacturers, the machine can pay for itself within a year or two by eliminating operating costs associated with alternative technologies.
Disadvantages
1. Safety Measures
Industrial lasers are not dangerous when used properly, but they do require appropriate safety measures.
To achieve foolproof laser safety, it’s essential to have a class-1 laser enclosure to ensure that the laser beam and its reflections are perfectly controlled. Handheld lasers are not recommended, as they make laser safety more difficult to control. Many manufacturers forbid their use for this reason.
Laser surface treatments also generate dust and fumes that need to be extracted to prevent contaminating surfaces, but also intoxicating workers. A laser fume extractor configured using a Material Safety Data Sheet (MSDS) is essential to extract dust and fumes specific to your materials and contaminants.
2. Cost
Laser technology offers impressive benefits, but it is not for everyone’s budget.
Acquiring a laser requires a high initial investment. For a turnkey solution, you’re talking about at least $140 000 for a 50W laser installed in laser cleaning workstation (the most basic solution). This means that lasers are generally not a good fit for low-volume applications where it’s hard to justify such an investment.
3. Incompatible Applications
While lasers are extremely good at applications requiring precision, there are important limitations that can make it a bad choice for some manufacturers.
- Lasers are limited by their line of sight. This means that certain types of parts or areas can be difficult to clean. For example, cleaning the inside of a tube is not possible with a laser.
- Thick coatings and mill scale take a long time to remove. While lasers can remove these materials, they are typically not a good solution because the laser processes are too slow.
- Lasers are unable to remove clear coats because the laser’s wavelength is not absorbed effectively.
- Lasers may not be a good fit to process large surfaces. This is because lasers are limited by their spot size. The spot size is a parameter that controls the size of the surface area targeted by the laser beam. Larger spot sizes can cover more area at once at the cost of a less focused laser beam. In essence, this means that lasers may not be the best solution to cover large surfaces quickly as their speed is limited by the size of the laser beam.
Laser Cleaning of Metals
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Laser cleaning is a surface treatment that can remove oxides, coatings, as well as a wide range of contaminants from metal surfaces.
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 Selective laser cleaning of e-coating on metal. |
Laser Texturing of Metals
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Laser texturing is a complete surface treatment for metal parts. It cleans, textures, and modifies the chemical composition of metal surfaces in a single operation.
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 A linear pattern etched into the surface of a metal part. |
Laser texturing can be used to prepare metal surfaces for any type of coat, seal, or adhesive. For example, some of our customers use it to prepare metals for thermal spray coating and adhesive bonding.
Choosing Between a Single-Mode and Multimode Laser
When choosing a laser, you can choose between a multimode laser and a single mode laser.
Multimode lasers have a larger spot size as well as a higher available laser power, making them ideal to clean larger areas in a shorter time.
Single-mode lasers have a smaller spot size, which allows them to focus more energy on a small area. This creates the conditions needed to etch metals. As a result, they can be used to both clean and texture the surface—something that cannot be done with a multimode laser.
7 Examples of Surface Treatments with Lasers
1. Texturing Batteries for Adhesive Bonding
Adhesives are increasingly used in EV battery packs to reduce weight, improve the load-bearing strength, and optimize thermal management. Laser texturing is used on battery cells and housings to improve the strength of adhesive bonds.
2. Texturing Turbos for Thermal Spray Coating
Thermal spray coating is used on turbine housings to improve properties like heat resistance, wear resistance, and corrosion protection. Laser texturing before thermal spray coating creates the ideal microstructure on the surface of the housing to ensure strong adhesive properties.
3. Cleaning E-Motor Housings for Liquid Sealants (Gasketing)
Sealants are used to achieve the high IP rating needed in e-motors. Before the sealant is applied, laser cleaning removes oxides and contaminants to ensure a high-quality bond between the sealant and the aluminum surface of the housing.
4. Stripping Powder Coating from Hairpins Before Welding
In e-motors, hairpin windings are covered with an epoxy resin powder coating to insulate them within the stator. Laser cleaning is used to expose the bare copper before welding to ensure that the epoxy does not penetrate the welds.
5. Stripping E-Coating from Seat Brackets Before Assembly
Laser cleaning is used to remove the e-coat from areas used for assembly on seat brackets. It exposes the bare steel to ensure that the e-coat does not diminish adhesion during assembly. The process shown in the video perfectly demonstrates the selective capabilities of laser cleaning.
6. Oxide Removal from Slip Rings to Improve Current Transfer
Laser cleaning is used to remove copper oxides that form on slip rings. This improves the current transfer between slip rings and brushes to optimize the performance of the electric motor.
7. Electrolyte Removal from Battery Cells to Prevent Corrosion
Liquid electrolyte can end up on critical components of cell casings, causing issues like short circuits and corrosion. Laser cleaning is used to remove electrolyte, liquid or dried, as well as other contaminants on the surface of battery cells.
Conclusion
Laser cleaning and texturing have the potential to improve the precision, speed, and repeatability of metal surface treatments—all while reducing operating costs significantly. If you are interested in discussing a cleaning or texturing application with a laser expert, contact us today.
