There are several companies that offer a motorized tool for removing slag build up from slats.  Some have moderate success in preventing slag build up by spraying the slats with a solution that is very similar to anti-spatter for welding.  However, the best, long term solution is to use copper slats.  While the upfront investment is significant, after 4 to 5 years, when it is time to replace them, you receive a good portion of your money back for the copper scrap. 

Another cost saving tip is to make sure that you develop slats that are double-sided so that when the top side becomes too worn, the slat can simply be flipped over.  The reason why the overall height of the slats is so important is because this affects how high the material sits inside of the laser.  When the slats become too short, the laser will experience height sensor alarms when processing thin gauge material because the Z-axis travel is close to exceeding the soft-limits of the machine’s parameters.