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Multiple Lasers in Metal AM a Blessing and a Bane

Richard Grylls
By Richard Grylls Technical Director for North America, SLM Solutions NA Inc.

Reality sometimes bites. As I write this, a machine in our applications development center in Wixom, Michigan, is idle.

The nine-day build for a major aerospace customer failed seven days in because of an unexpected problem, so we had to scrap the part and start again.

Anyone using 3D printers is familiar with arriving in the morning (or receiving an e-mail from the machine in the middle of the night) to find a failed build, for a variety of reasons.

As the technology matures, and users and system manufacturers become more knowledgeable, failures diminish and uptime increases. Redundant systems, uninterruptible power supplies, intelligent pauses, process controls and optimized process parameters all play a role in achieving high productivity from a metal additive manufacturing system.

SLM Solutions pioneered multiple laser systems and has taken a leading position in productivity improvements in recent years. The newly re-launched SLM280 offers not one but two 400-W lasers, and the SLM500 comes with four 400-W lasers. The latest systems also offer 700-W configurations.

Multiple and higher-power lasers bring one main, significant benefit: higher productivity. In general, switching from one to two lasers nearly halves the build time. The SLM500 with four 700-W lasers offers game-changing productivity increases: Parts that were uneconomical to build with metal AM suddenly become very cost-effective.

However, multiple lasers can also bring some extra challenges and decisions.

If the user is building many small parts, it makes sense to build some with one laser and some with the second laser.

However, if you’re building one large component, both lasers need to work on the same part, and so the alignment of the two lasers to each other, and the manner in which they work together to build the part, become critically important.

If one laser is doing most of the work with the other laser melting much less material and sitting idle much of the time, the benefit of multiple lasers is largely lost. If the lasers are not properly aligned, there will be an obvious witness mark—maybe a step—on the surface of the part, or worse, an actual defect where some material is unmelted.

SLM Solutions has worked for years with hardware, software and procedures to push through the challenges and devise a workable solution for multiple laser builds for many industries and components.

Challenges remain, however, and are likely to continue as the industry looks to further increase both throughput and the build capacity of metal powder bed fusion machines. As the size and value of the parts produced on the machine continues to increase, the stakes continue to rise, and quality and robustness continue to be of critical importance.

The market will eventually find the balance of build chamber size, laser count, laser power, system cost and reliability. The value proposition for large multilaser machines is quite compelling, but if a $100K part build fails just before completion, the benefits become harder to justify. The exact size, format, number and type of lasers and useful applications are still very much open questions in many industries. The benefits are substantial, but there will be more than a few headaches along the way toward large-scale serial production.

The drive for increased productivity from metal AM processes is relentless. Moving from a single-laser system to a twin- or quad-laser system provides a step-change in productivity that opens up new applications that weren’t previously economically feasible. Smaller, less “marketing-friendly” features, such as the removable/swappable build chamber in the SLM500, mean that that machine in our application center—the machine that I mentioned was sitting idle—is back up and running now: Getting it fixed only took as long as it took me to sit down and write this guest column.

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