30 Years of Innovation: Dependable Laser Sintering Enables Sustainability in AM

In 2020, we celebrated Materialise’s 30th anniversary. Our 30 Years of Innovation blog series highlights some of the different 3D printing technologies that have helped our customers achieve their ambitions over the years and shows that there is no one-size-fits-all approach to 3D printing. This time, it’s the turn of selective laser sintering. 

Laser sintering is a popular and versatile 3D printing method that uses — you guessed it — lasers to bind powder particles together. Because of its adaptable process and high-quality output, laser sintering works well with a wide range of applications, from prototyping to series production. 

Selective laser sintering is used quite frequently in 3D printing — and for good reason. As an affordable, quick, and accurate technology, it checks off many boxes and is a great option for serial production. 

“One advantage of laser sintering is its productivity. Because parts are printed in a power bed, no support structures are needed, and you can really optimize each build to its fullest. This is especially useful in series manufacturing because you can print many copies of the same part in one go. 

Another benefit is the quality of the parts. Laser sintered parts have very good mechanical properties compared to injection-molded parts of the same material. Selective laser sintering creates robust parts,” explains Giovanni Vleminckx, Research Project Manager at Materialise. 

Laser sintering’s advantages also bring great value to prototyping.  

“On top of these other capabilities, laser sintering is fast, which is crucial for prototyping. Having the ability to nest many parts in the same build means that you can use one run of the machine for one-off parts, often prototypes, from various customers if they are the same material,” says Giovanni.  

“This chips down the lead time and decreases the cost because you can spread the cost of your single run among more parts. AM is fantastic for rapid prototyping, and that value really shines through with selective laser sintering.” 

At Materialise, we currently offer seven materials for selective laser sintering and many more finishes. Since it’s such a versatile, reliable option, laser sintering is a great match for many applications, ranging from a queen’s crown to acoustic panels to eyewear. 

Laser sintering’s usefulness is proven in both one-of-a-kind projects and repeat series. Its capabilities, such as the ability to print hinges and interlocking parts, allow designers to look at traditional products through a different lens. An example of this is the unique ONE_SHOT.MGX stool and beautiful 2.7-meter wedding veil shown above. In addition to this mobility, selective laser sintering was chosen because the wedding veil could be printed folded over itself within the powder bed to create the length. 

In mass production instances, laser sintering shows its value in applications like eyewear. At Materialise, laser sintering is often our go-to for eyewear applications for its high quality and ability to print many parts in one build. Plus, selective laser sintering provides the style and reliability that consumers need in their eyewear thanks to a wide variety of colors and finishes, impressive mechanical properties, and skin contact safety that will last throughout the accessory’s lifetime. 

Back in 2014, our team questioned how we could make selective laser sintering more sustainable. The powder used during this process could be recycled, but only when combined with fresh material. That means that only about 50% of each build can be recycled powder. The rest of the used powder, unfortunately, goes to waste. 

So, backed by the European Commission and VLAIO, we began tweaking laser sintering to develop a reliable process using 100% reused powder. Six years later, in 2020, we were finally able to share it with the world in the form of our new material that enables us to print parts using a more sustainable method: Bluesint PA12. 

Bluesint uses the same material powder as our laser-sintered PA12. Instead of throwing away the excess used powder, we can now use it to fill our specially designed laser sintering machines and print parts with impressive properties. 

Before this unique process was made possible by our team, the major challenge keeping manufacturers from using machines with only reused powder was the lack of quality in the resulting part. 

“Previously, builds using 100% reused powder created parts that had an ‘orange peel’ — low surface quality that resulted in a wavy texture,” explains Tom Craeghs, Research Manager at Materialise. “In the years that we worked on this research, we had to find the exact order of steps and parameters that would prevent ‘orange peel’.” 

The magic formula was a dual laser system, powered by Materialise software. 

“Because laser sintering machines are open systems, our team was able to fine-tune the parameters and, through much trial and error, finally develop the intelligent scanning strategy that builds a great material consisting of only reused powder,” says Tom. “Thanks to our team’s unparalleled expertise, our Build Processor to set these parameters, and the Materialise Control Platform to steer the process, we’ve created a laser sintering process that empowers our customers to make sustainable choices.” 

Now, we’re able to build an eco-conscious version of our PA12 that offers the same mechanical properties. When you compare the two materials, stiffness, strength, long-term stability, and chemical-resistance are the same — the only difference is in surface quality. Bluesint PA12 has a slightly rougher surface quality, so it is a great fit for functional prototypes. And since prototypes have the sole purpose of validating designs, Bluesint is a wonderful opportunity to make prototyping more sustainable.