Direct Metal Laser Melting

Direct Metal Laser Melting (DMLM) technology has the power to help businesses build the next generation of applications, today. Offering high productivity and lower cost per part compared to traditional manufacturing, DMLM is an innovative technology for manufacturing in the aerospace, medical and industrial manufacturing industries.

The DMLM process

DMLM is an additive manufacturing process that uses lasers to melt ultra-thin layers of metal powder to build three-dimensional objects. Parts are built directly from an .stl file generated from CAD (computer-aided design) data. The .stl file is converted to a sliced file through our machine software, which is uploaded to a machine for the build process. The use of a laser to selectively melt thin layers of tiny particles yields objects exhibiting fine, dense and homogeneous characteristics.

The DMLM process begins with a recoater spreading a thin layer of metal powder on the print bed. Next, the sliced file generated lays down the scan paths that control the exposure of the laser to melt the powder and create a cross-section of the object. The print bed is then lowered so the process can be repeated to create the next layer. After all layers are printed, the excess unmelted powder is brushed, blown or blasted away. The final part sometimes requires little, if any, finishing.

Video transcript
Direct Metal Laser Melting or DMLM is a powder bed fusion additive manufacturing process. DMLM uses one or more lasers to melt ultra-thin layers of metal powder to build three dimensional parts. The parts are built from CAD files and converted into slice files. The slice files are then uploaded to the DMLM machine. During the DMLM process the re-coater moves across the build platform evenly spreading a fine layer of metal powder. A cross section of the part is melted based on a layer of the slice file. The build platform is then lowered, and the next layer of powder is distributed and melted. In the case of multiple lasers overlapping areas are stitched together to create a seamless part. The superior gas flow within the build chamber helps to keep a clean environment ensuring a better part quality. When the part is completed, the platform is raised and removed from the build chamber. The excess powder is removed from the finished part. GE’s Concept Laser DMLM machines minimize the effects of process variations resulting in fast builds that can improve part quality, get parts to market faster, and help reduce costs.

Laser Anthology

What are some of the complexities and realities of machine development? What do repeatability and reliability mean in practice? What rigor and technical maturity are needed to develop industrial-scale systems? In this anthology our team guides you through some of those questions and offers an insight into their respective fields of expertise. They’re ready! Are you?

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The power and precision of lasers used in the DMLM process make it possible to use extremely durable metals delivered as fine powders. Machines using Direct Metal Laser Melting produce elaborate yet super-strong parts used in demanding applications in aerospace, auto racing and medical industries, among others.


Titanium is one of the most popular materials used in the Direct Metal Laser melting process. Titanium parts endure high pressures and temperature extremes. Parts fabricated by DMLM machines are valuable where a quick turnaround of limited product runs is a strategic advantage.

Stainless Steel

Since stainless steel is known for its strength, toughness and ductility, it is frequently used to print functional prototypes and production parts. When low-carbon content is required, 316L stainless steel is an option. It is a tough, ductile, weldable compound that is highly resistant to pitting and corrosion. Maraging steel is used to create conformal cooling channels important in injection molding. This tooling steel is readily machined and easily polished in post-processing.


Alloy718 is a nickel-based superalloy with properties required in rocket and jet engines. Its heat and corrosion resistance also make it ideal for use in various chemical industry applications. CoCr F75 is a cobalt-based superalloy offering high-temperature resistance and toughness. It is also used in the printing of turbine and engine parts.


Aluminum alloys possess excellent fusion characteristics that are important in additive manufacturing. DMLM is used to create hard aluminum objects capable of handling significant loads. Highly machinable aluminum components are used in automotive, racing and thermal applications.

General Electric

Frequently asked questions

What are the best DMLM applications?
Designers take advantage of the fact that Direct Metal Laser Melting yields intricate parts that reduce weight while retaining requisite strength and durability. Parts are often used in applications where weight reduction is vital, as in satellites, rocket thrusters and jet engines. Robotics and injection molding also benefit from the low-run, highly durable precision components produced by Direct Metal Laser Melting.

The temperature and pressure extremes in a rocket engine make it the perfect laboratory for demonstrating the unique capabilities of DMLM. The propellant of choice in rocket engines is typically liquid hydrogen — a lightweight fuel with a high exhaust velocity and high reaction rate. However, liquid hydrogen must be stored at minus 423 degrees F. At combustion, it generates temperatures exceeding 5,500 degrees F.
What are the DMLM advantages?
High-precision DMLM parts possess exceptional surface characteristics along with mechanical properties equivalent to those found in traditional wrought materials.

Surface quality and minimal porosity are two key advantages of the Direct Metal Laser Melting process. Since it is possible to move the print bed in as little as 20-micron increments, objects exhibit a smooth surface quality that minimizes the need for post-production finishing. To put a thickness of 20 microns in perspective, consider that the diameter of a red blood cell is about five microns, and a human hair is about 75 microns thick.

The Direct Metal Laser Melting process minimizes the porosity common with sintering. In fact, it is possible to achieve close to 100 percent density. Enterprises can reuse the valuable unmelted metal powders.

Direct Metal Laser Melting offers short lead times ideal in situations where repeated testing of functional metal prototypes is necessary. Where traditional production times are often measured weeks, the direct metal laser melting process only requires hours or days.

The DMLM process gives designers the freedom to create objects with intricate structures and significant undercuts that are usually impossible to create using conventional methods. Quicker design cycles are vitally important in the highly competitive environments common in many industries. DMLM makes possible a design-driven process with significant benefits.

How does DMLM compare to DMLS?
The direct metal laser sintering (DMLS) process uses lasers to partially melt particles so they adhere to one another. The DMLM process is very similar, except that the material is completely melted to create ultra-thin liquid pools, which solidify as they cool.
The term “DMLS” is often used to refer to both processes, although the term “DMLM” is gradually emerging as the preferred way to reference the process when complete melting occurs.
What is Selective Laser Melting (SLM) and Selective Laser Sintering (SLS)
SLM and SLS are two AM processes differentiated by the degree to which materials are melted. SLM involves the full melting of material, while SLS involves sintering (partially melting) material. In both instances, the term “selective” refers to the precise melting of ultra-thin layers of build material.

SLS is a lower-temperature process than SLM, although SLS still produces parts with dimensional accuracy and complex geometries. Support structures are not required during printing. SLS uses either single- or dual-component powders. When using the latter substance, lasers melt away the outer layer, and the inner material fuses with adjacent particles.

With SLS, it is possible to reduce shrinking and warping by heating the build chamber to a temperature just below that required for sintering powdered metal alloys, plastics, glass and ceramics. Surface porosity commonly associated with sintering is addressed with the application of a sealant.

Since selective laser melting (SLM) requires complete melting at very high temperatures, object distortions and stresses are more of an issue. However, full melting minimizes porosity.

Stresses introduced by the high-temperature SLM process make it vital to keep the object firmly secured to the print bed during printing. A heated build chamber combined with proper support structures helps to minimize distortion. Post-processing heat treatment while the object is still on the platform also reduces internal stresses. The SLM process uses atomized metallic powders, including titanium, tungsten, maraging steel, cobalt chrome, stainless steel, aluminum and copper.