Direct Metal Laser Sintering (DMLS) is one of the major technologies in additive manufacturing (AM). It is known for making precise and extremely dense metal parts in single or small-lot quantities. DMLS-made parts are common in medical, aerospace, dental and other industries that need smaller, geometrically complex parts.  If a part cannot be made using traditional metal manufacturing methods, DMLS could be a good alternative choice.

As with other AM processes, DMLS begins with a data cloud file from a CAD program loaded onto the 3D printer. The DMLS machine uses a blade to sweep a layer of metal powder onto and across the build platform. Then a laser beam moves over this layer in a pattern called for by the data cloud file. As the laser moves, it melts (sinters) portions of the powder to the layer below it. Then a fresh layer of powder is spread over the build platform.  The laser moves across the build platform again, sintering various portions as commanded by the build program.  This new layer in its sintered state bonds to the previous layer. This layer-by-layer process repeats until the part is complete.

Protolabs has been offering DMLS services since 2012.  Today, the company has 25 Concept Laser Mlab and M2 DMLS 3D printing machines and a Velo3D printing machine, all certified to ISO 9001 and AS9100D.  That’s a lot of capacity for metal prototyping and low-volume production needs.

These machines offer large build sizes, produce accurate parts, and provide quick turnaround times, with good surface quality and fine component structures. The large build platforms of the Concept Laser M2s are suitable for higher part volumes. All of Protolabs additive manufacturing equipment handles both reactive and non-reactive metal powder.

Even though these machines deliver good surface quality, parts will still need some post processing. Protolabs offers a range of post-processing capabilities to ensure good finishes.  Protolabs employs five full-time machinists to operate a number of mills and CNCs that are used to smooth away rough surfaces, machine mating surfaces, and hone part tolerances.  In some cases, more advanced heat treatment processes are performed to enhance material properties.  Other secondary processes for post-processing can include tapping and reaming.

How to begin with DMLS

Protolabs offers an easy process to get your design prototyped. All you need to do is upload a part online, and you’ll receive feedback on lead times and pricing quickly.  You may also receive tips on your design that will make it easier, less expensive, and faster to prototype.  Notes David Bentley, Senior Manufacturing Engineer, “Probably the most important step when designing a part for DMLS is to involve us early.”

Each additive technology has different requirements, so it’s important to design for the specific additive process.  This is where Protolabs engineers’ experience can really make it easier to get the part you have in mind.

Typically, once you’ve loaded your design onto Protolabs order entry engine, the following will happen:

1. Protolabs engineers will thoroughly review the design. For example, the review will help determine the best placement for support structures and the best part orientation.
2. Then, you will be asked to select a material. Even though DMLS works with a range of metal powders, each brand of DMLS machine works better with some metal powders than others. Some of the materials available at Protolabs for DMLS include:

Aluminum / ALSi10Mg
Cobalt Chrome
Inconel 718
Stainless Steel 17-4 PH
Stainless Steel 316L
Titanium / Ti 6AL-4V

Certain materials fit application attributes better than others. For example, when the part needs strength, consider Inconel, Titanium, and Stainless Steel. When low weight is important, look into Aluminum and Titanium. For corrosion resistance, Stainless Steel, Inconel, Titanium, and Cobalt Chrome will fit.  And for the combined needs of high strength and low weight, consider Aluminum, Titanium, and Cobalt Chrome.

Protolabs also has its own test lab to explore material properties of tensile strength, hardness, microstructures, and coordinate measuring.  As a digital manufacturing provider, Protolabs offers powder analysis, material traceability, process validation, and inspection reporting.

That’s it.  Once everyone agrees on the design, it is sent to the DMLS printer and built.  Depending on part complexity, you’ll usually have your prototype in three to five days.

So, consider DMLS when:

• You need to make part with complex geometries
• Reducing weight, also known as lightweighting, is a need.
• When a design can consolidate parts
• When customization is a need
• When a design is developed with Topology optimization programs
• When you can cut costs.

Protolabs
www.protolabs.com