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What’s the Difference Between SLS and SLM?

June 30, 2014

What’s the difference between Selective Laser Sintering (SLS) and Selective Laser Melting (SLM)? The truth is that they are very similar processes that differ primarily in the materials that they use. Here’s one of the better descriptions I’ve found that explains it:

“Selective Laser Sintering and Direct Metal Laser Sintering are essentially the same thing, with SLS used to refer to the process as applied to a variety of materials—plastics, glass, ceramics—whereas DMLS refers to the process as applied to metal alloys. But what sets sintering apart from melting or ‘Cusing’ is that the sintering processes do not fully melt the powder, but heat it to the point that the powder can fuse together on a molecular level. And with sintering, the porosity of the material can be controlled.

“Selective Laser Melting, on the other hand, can do the same as sintering—and go one further, by using the laser to achieve a full melt. Meaning the powder is not merely fused together, but is actually melted into a homogeneous part. That makes melting the way to go for a monomaterial, as there’s just one melting point, not the variety you’d find in an alloy. To nutshell it, if you’re working with an alloy of some sort, you’ll go SLS or DMLS; if you’re working with say, pure titanium, you’ll go with SLM.”

So in lay terms, SLM is stronger because it has fewer or no voids which helps prevent part failure but is only feasible when using with a single metal powder.

When to Use SLS vs. SLM

Because additive manufacturing works by building up layers instead of removing material, SLS, SLM and other 3D printing technologies are most useful for products with complex internal geometries like spiral vents and nested cores, or for rare metals that would be prohibitively expensive to machine. 3D printed metal can also be an effective option for manufacturing very small batches of metal parts or for projects with very short timelines.

In other cases, 3D printing metal is often substantially more expensive than CNC machining, especially for medium- to large-sized productions. Though it has longer lead times, machining is still quite cost-effective for small batches and becomes substantially less expensive at medium to high volumes. Moreover, metal machining yields superior fine detail and surface finish when compared to printed metal.

At the same time, other modern 3D plastic printing technologies like the HP Multi Jet Fusion 3D printer, are extremely cost effective for small- to medium-sized productions. The Multi Jet Fusion (MJF) is able to print industrial-strength parts at a fraction of the cost of SLS and SLM. It’s quicker, too; MJF printing is many times faster than any other 3D printing technology, machining or injection molding. Depending on the demands of your project, plastic printing may even be a viable alternative to metal printing.

The Best Manufacturing Technology?

At RapidMade, our team of engineers deploy a wide range of traditional and additive manufacturing technologies to ensure that you always have access to the best manufacturing technologies for your needs. Whether you are working with metal or plastic—3D printing, molding or machining—our 3D Printing Services are dedicated to creating high-quality, cost-effective products. If you have a product you want to manufacture or an idea you want to prototype, get started with a quote today. Our team will review your project and we’ll get back to you with a quote in 24 hours or less.

Have other questions about SLS, SLM or other manufacturing technologies? Contact us for more information! We’re always happy to hear from you.

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