By Catherine Veilleux on January 18, 2023
Laser Cleaning
Laser structuring, also known as laser texturing, is a process that uses a laser beam to etch patterns (or microstructures) over a surface. It is used to modify the surface of metals, polymers, ceramics, and composites to improve properties like adhesion, wettability, and conductivity. The surface treatment is common in manufacturing and medical applications.
In metal manufacturing, laser structuring is increasingly used to prepare surfaces for adhesive bonding and thermal spray coating, creating a surface texture that improves adhesion while removing contaminants that could interfere with it.
Benefits & Advantages of Laser Structuring
- Complete surface preparation in a single operation
- Masking no longer needed when replacing grit blasting operations
- No consumables
- Low operating cost and low maintenance
- Easy to automate
- Green technology
- Non-contact laser processing
- Chemical and mechanical changes on the surface lead to stronger adhesive properties
Laser Structuring Applications
Laser Structuring for Adhesive Bonding
Adhesive bonding has been replacing traditional joining techniques like welding and mechanical fasteners (bolts, screws, rivets, clips, etc.) The process offers a range of benefits. For example, the structural adhesives used to join surfaces together allow for lightweight designs, generate no thermal distortion, and evenly distribute stress over the entire bonded area.
Laser structuring can be used to prepare surfaces for adhesive bonding. It is used, for example, to prepare the bonded surfaces of structural batteries in electric vehicles.
Some of the benefits of laser structuring for adhesive bonding include:
- Better bond strength
- Better chemical and mechanical interlocking
- Lower chances of bond failure
- Improved wettability
- Slower aging of bonded joints
Laser structuring has been compared to other surface preparation methods (chemical etching, plasma cleaning, and abrasive blasting), showing that it provides a better bonding quality.
Laser Structuring for Thermal Spray Coating
Thermal spray is a process that uses a gun to spray molten material onto a surface and coat it. The process makes parts more resistant, granting surface properties like corrosion protection, thermal resistance, wear resistance, and more.
Before the thermal spray coating process, the surface must be prepared to obtain a good bonding quality between the substrate and the coating. Laser structuring provides both surface roughening and surface cleaning, making sure that no contaminants interfere with the bonding process, and increasing adhesion with a rough surface.
Turbo housings (as shown in the previous video) and fuel cell bipolar plates are examples of parts where laser structuring is used to prepare surfaces for thermal spray coating. It replaces other surface structuring processes like grit blasting and, with the high precision of lasers, eliminates the need for masking.
Other Laser Structuring Applications
Laser structuring is also used for the following applications:
- Mechanical seals: Laser structuring improves the performance of mechanical seals by creating patterns that retain lubricants, reduce friction, and increase the seal’s durability.
- Laser cladding: Laser structuring improves the clad material’s adhesion to the surface through precise, defect-free surface preparation.
- Paintings & coatings: The microstructure created by laser structuring improves the adherence of paintings and coatings.
How Laser Systems are Configured for Laser Structuring
Laserax has developed the optimal configuration for laser structuring in metal manufacturing. Our configuration offers a high-speed process that maximizes quality and minimizes cost.
Our tests have shown that the following laser configuration is optimal for most laser structuring processes in metal manufacturing:
- The 1,064 nm wavelength generates a good reaction with metal surfaces
- Our nanosecond pulsed fiber laser source offers the high power needed for structuring applications at a lower cost than other laser technologies
- The laser pulse duration varies between 20 and 500 nanoseconds based on the needs of the structuring process (for example, to reach higher energy levels)
- The laser fluence value (i.e., the energy level delivered in a given area) must be above the laser ablation threshold of the metal so as to remove contaminants and roughen the metal surface.
- A single-mode laser is required to etch the surface
- Parallel line patterns are typically etched on the surface to gain in processing speed and guarantee optimal results
Note that for other applications than metal manufacturing, different configurations may be used. In medical applications for example, a higher level of precision is needed, which requires femtosecond laser pulses (more expensive) instead of nanosecond laser pulses.
The Effect of Laser Structuring on Metal Surfaces
Laser structuring uses the power of a focused beam of light to etch metal surfaces, creating a precise pattern that is repeated over a surface area and whose depth is computed in microns. Lines are the most typical patterns, but other patterns include dimples, circles, grids, diamonds, and even random.
During the laser process, the laser beam instantly vaporizes the surface of the metal. Around the beam, the heat from the beam is sufficient to melt the metal for an instant. In about a hundred nanoseconds, the molten metal resolidifies, creating protrusions around the laser path. During this process, surface oxides that will contribute to a better adhesion are created.
The patterns etched on the surface also increase the contact area between the metal surface and the material that will be joined to it, improving their adhesion.
Laser Structuring in Production Lines
Laser structuring is a flexible and versatile manufacturing process that can be easily integrated into existing production lines, making it an attractive option for manufacturers. High-power laser systems can be integrated directly in production lines to keep up with demanding requirements.
