Laser marking of blackened steel – Application for Humphries Engineering
These small clip mechanisms use laser marking to place the batch number onto the surface. The blackened finish has to be removed in order to create a visible mark to the surface.
These small steel clasps are used on ammunition boxes as part of security measures in storage. The process of blackening the steel makes the surface quite hard, and so a larger than usual amount of energy is required to penetrate the surface blackening to expose the base material. The gold colour effect to the surface, is due to the steel burning during the process. A second pass could be used to clean this up and provide a more silver colour. Commercial decision was made to leave the second pass out ensuring the most attractive price was made available.
Due to the size of the parts, and the amount of data required, special jigging is used to locate the clasp very accurately each time.
A Q-switched Nd:YAG laser was used, due to its power output capability. With low frequency settings used, each pulse is available with high power levels, ensuring that break through to the base material is effective. The surface is very hard, and care must be taken during the laser marking process, not to create a dark mark which would obviously be difficult to read. Because of this, we skim the surface with low power a number of times to break through to the base material creating a lighter marking result.
In many cases, product in this process format will be supplied oiled. We do not have to dry or remove the oil. The laser will still be effective through a wet oil layer. Obviously, there will be limits to the amount of oil covering.
If you would like further information on this application, or any other application, please request a call back or, talk to one of our laser marking specialists by going to our contact page – link below.