With the partial success of printing copper I found that Bronze with a much lower heat conductivity could be very interesting. After doing some simple tests I found that bronze is actually very easy to process. The energy absorption seems to be very similar to copper but the reduced conductivity makes this easier to print than stainless steel. I have been using a bronze with 85% copper and 15% tin, the nice thing is that this powder is also less expensive than stainless steel.

I have been doing the first tests with copper powder. From the first test it is clear that it is possible to print copper with the blue 30 watt laser.

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 have started recieving all the components of the new printer and I have started the assembly process, not all components have arrived but it is almost ready to start the motion system testing.

A selective laser melting machine contains a couple of risk that need to be mitigated so the machine can be used safely.

The last month I have been focussing on determining and improving the product density and also the skin of the 3d printed products. This is done by printing a lot of density cubes. Since the last update I have printed in total 68 density cubes to try to improve the density. The density is dertermined by first measuring the weight of the density cube and after that determining the volume by floating the cube under water, this gives the displacement of the water in grams and 1gram=1cm3.

Today i assembled the first pistons of the production model. The right part is fully assembled and the left one is only semi assembled and is still missing the seals and the 3d printed connection part that I will be printing on monday.For the next few months these pistons will be running an endurance test with 2000 layers being done in about 15 minutes. This will do almost 2 years of movements in little over 7 days.

The latest result of the process development really improved the quality of the part. the part on the right is the latest one, the one on the left is the one before that.