For sample marking on ball bearings, we applied marks with two different procedures for demonstration purposes: laser engraving on the outside, laser annealing on the inside circle. Both markings are robust and durable. For heavily used metal substrates like some bearings, the preferred marking method is often laser engraving, because the marking remains readable even in highly abrasive use.
The annealing process heats the surface to temperatures of 200 to 360 degrees Celsius (390 to 680 degrees Fahrenheit), which generates a colored or black oxide layer only a few micrometers thick. The surface itself remains unaffected.
In the laser engraving process, targeted surface particles are removed, partially due to evaporation, partially due to melting, which results in imprint marks of up to several tenths of a millimeter deep. Such engravings can resist even high abrasion or wear. Additionally, it is also possible to apply a paint layer to the metal surface without the marks disappearing.
Typical applications for engraving are automotive parts, embossing tools (stamping tools) or injection molds. Annealing marking is effective for products made of stainless steel or titanium, and also for all other ferrous metals.