Wilkes is the person in charge of all engineering groups involved in designing the machines and making sure they function correctly. These include the chemical, electric, hardware engineering, software development, process and material development teams, as well as a technology development group and product management group.
“The advantages of multiple lasers are evident in terms of speed in the build rate and productivity,” he immediately clarifies. “Having four lasers means you can reach productivity that is more than 3 times as fast as single laser machines, this is a very significant increment.”
Wilkes is now working on powering up the lasers, which, in a way, is the same idea of using a bigger nozzle on filament-based machines. The machine currently works with four 400-watt energy sources, and the engineering team is studying an upgrade to four 700-watt lasers.
“Increasing the laser power is tricky and is not sufficient for incrementing speed,” Wilkes explains. “A more powerful laser increases the size of the meltpool and that generally means that the resolution and surface quality becomes poorer. You cannot just increase the laser power to 2, 3 or 5 KW without losing part quality. We found that we can manage 700 Watt and achieve approximately the same quality as 400 Watt lasers. Increased laser power is particularly beneficial to aluminum alloys.”
For example, says Wilkes, with a typical aluminum alloy you can increase scanning speed up to 100% compared to a 350-watt laser. However, he warns, you cannot push significantly beyond that: you cannot have 2 KW laser and still achieve the same quality. More lasers – even beyond four beams – is an alternative approach that SLM Solutions is going to look at in the future.
“It is not a principal difference in terms of algorithms when you use 4 or 8 lasers,” says Wilkes. “One thing that is particularly tricky in the multiple laser setup is the alignment of the lasers with each other. That’s because, if you are building a large part with all lasers in parallel, they have to be aligned with extreme precision.”
As anticipated, the SLM 500 HL is now capable of 3D printing some of its own parts. Wilkes showed me one that is visible, and of course it looks just like any other part. He also said that some of the complex parts on the inside are built by SLM, which, of course, makes perfect sense. Machines building themselves and engineers optimizing every aspect of the production cycle: that is why the speed of metal 3D printing is increasing exponentially, doubling approximately every two years. Today we are talking about going from two to four lasers; one day we may be considering going from 128 to 256. SLM Solutions will probably have a solution for that too. Discuss your thoughts on this new technology in the SLM 500 HL 3D Printer forum over at 3DPB.com.