If you’ve searched the internet about laserable materials you might have decided that plywood is the most popular sheet material out there. And, you might be right which is no surprise given that it’s a very versatile material due to its strength and the solid-wood look of its surface. However, the glue used to bond the layers (i.e. the plys) together can give off noxious and toxic fumes when burned, and is also difficult for a laser to cut. Also, the glue and its thickness can vary around the sheet, making cutting potentially inconsistent.
That’s why using a LASER mounted on a CNC machine means we really need to make sure the plywood we use is LASER-safe. LASER-safe plywood has a special glue that reduces the fume problems and is easier and more consistent to cut. So, to see how useful it can be with my 5W diode-LASER I tested cutting a piece of 3mm thick LASER-safe Birch plywood. The results are shown in the photo above. I found that two passes, at 100 mm/min, around 100% power was successful at cutting right through.
However, probably due to variations in glue thickness, and some curving of the sheet (and maybe water content variations: my meter said 8% although it’s hard to be sure with plywood) for some cutting I find I really need three passes. Below is a photo of the back of the test sheet, which showed that cleaning up the burn marks isn’t a small job, but nonetheless isn’t so bad that it’s not worthwhile.