Laser marking blank metals using a CO2 laser is only possible with the addition of a laser marking solution such as a spray or paste. The solution must be applied prior to laser marking, as it needs to dry before being processed. The laser will burn into the solution when marking, and once the process is finished the excess solution should be wiped from the workpiece (stainless steel in our example).
It is essential when marking sensitive surfaces or expensive items such as watches to use a laser marking spray. A laser marking solution is classed as a hazardous material, therefore you must adhere to the relevant safety regulations to protect yourself and staff when using them.
A CO2 laser is not suitable for marking metals without an additional marking solution. For the metal to react to the laser a high power is required, while the process must be slow to achieve the result. This results in a lot of energy being introduced onto the material, which will deform as it is heated. In this instance the resulting engraving, such as small font, cannot be seen.
Applying the laser marking solution
Remove the marking paste
Deformation during CO2 laser processing without marking solution
Metal marking with a fiber laser
A fiber laser is the perfect laser marking tool for metals in regards to productivity and quality. When metal is processed with a fiber laser no additional marking solutions are required, negating pre and post processing. The marking result from a fiber laser is accurate and can produce incredibly fine details.
You can also produce different effects with a fiber laser by altering the parameters. As an example, you can use the annealing method which can produce a rich black or white colour when processing. The finished engraving result offers a depth to the material which is both long lasting and counterfeit proof.
Trotec offer a number of fiber lasers, from the flat bed laser plotter Speedy series to the industrial laser marking SpeedMarker series. The best machine for laser marking is dependent on your application.
SpeedMarker series
Speedy flexx series
Processing times of different laser marking methods
A Speedy flexx laser machine features both a CO2 and a fiber laser source. When comparing the processing times of the CO2 and the fiber laser, the marking time with a fiber laser is only 1 minute faster. However, processing with a fiber laser negates the requirement for additional marking solutions, saving the operator time and increasing productivity.
A SpeedMarker galvo laser marking machine is significantly faster.
There are a number of factors which you should consider when choosing to buy a laser plotter or a galvo laser, which you can find here.
