Since the new year I have been experimenting with aluminium powder and I can now conclude that this material cannot be processed by this system. Compared to conventional LPBF printers the blue laser diode should have almost 3x more efficiency than the infrared lasers that are used. Unfortionately there is also another factor at play since the aluminium has a very high thermal conductivity. I believe the problem lies in the absolute power of the laser spot, the blue laser has a relatively large spot size of 0.15*0.18mm. Compared with other systems that generally have a spot size of <0.1mm the watt/mm2 is about 3x lower. This causes the powder to only loosely bond and because of the large thermal conductivity of the build plate the powder does not fuse correctly to the build plate. I believe the system will have to go into the 100watt power range with the same spot size as now to be able to print aluminium.
I did see an improvement with a sandblasted build plate compared to a grounded one. Furthermore I also experimented with a composite build plate consisting of a normal plate with a 0.3mm layer of aluminium bonded to it with epoxy to reduce the thermal capacity of the build plate, this in the end gave the best result but still not good enough. The laser spot is just not bright enough.
The next material I will attempt will be copper, the absorption is almost 68% for the blue laser so there is a possibility that it just might work.
