Laser powder bed fusion (LPBF, also sold as DMLS or SLM) and electron beam melting (EBM, also called electron beam powder bed fusion) both build metal parts by spreading thin layers of powder and melting each cross-section. They differ in the energy source, and that difference changes the build environment, the temperature of the powder bed and how much stress is left in the part. Those in turn decide supports, surface finish, which alloys can be printed and how parts are packed in a build.
LPBF is the more widespread of the two. EOS, a major LPBF maker, names aerospace, automotive, medical, tooling and turbomachinery as its main markets. EBM is a smaller field. GE bought Arcam, the company that commercialized EBM, in 2016, and its successor Colibrium Additive is the main supplier, so much of the EBM detail here comes from Colibrium and is attributed.
Inert gas versus vacuum
A laser passes through gas without losing much energy, so LPBF machines fill the build chamber with inert gas to keep oxygen away from the melt. EOS's Ti64 process data sheet for the M 290 specifies argon, and Pasang and colleagues built their laser samples in argon for a 2021 comparison of the two processes. An electron beam behaves differently. Colibrium explains that collisions with gas molecules would sap the electrons' energy before they reached the powder, so EBM runs in a vacuum of about one-billionth of an atmosphere. Loughborough University cites about 1 × 10⁻⁵ mbar on Arcam machines.
The beam also carries electric charge into the powder. Colibrium says a small, controlled flow of helium prevents charge from building up, which would otherwise cause what it calls a smoke event, a small powder explosion inside the machine. For the same reason, Colibrium says EBM is unsuitable only when the material is not electrically conductive.
Preheat and residual stress
A vacuum chamber holds heat like a thermos, and EBM deliberately keeps the powder bed hot. Pasang and colleagues describe the bed held at about 700 °C for Ti-6Al-4V, above the stress-relieving temperature, while their laser samples were built on a bed at ambient temperature. Colibrium says its machines can heat each layer to 1,000 °C or more, and it markets its Spectra H for builds above 1,000 °C. Colibrium adds that because the powder starts closer to its melting point, each layer takes less time and energy to melt.
The temperature difference shows up as residual stress. Desktop Metal notes that the rapid heating and cooling in LPBF leave thermal stress and direction-dependent properties, so laser parts are typically stress relieved for several hours at 400 to 800 °C. Colibrium claims EBM cuts thermal stress by orders of magnitude compared with laser printing, so its parts need no stress relief. It also says the hot process allows crack-prone alloys that laser machines struggle with.
Supports and packing a build
In LPBF, supports do two jobs. Desktop Metal says they anchor parts against distortion and carry heat away, and that they are often removed by wire EDM or milling. Every part is therefore attached to the build plate. In EBM, the hot powder around the parts becomes partly sintered and gives some mechanical support. Colibrium says this lets parts be stacked from the build plate to the top of the envelope, sometimes floating free in the powder, and calls EBM the only additive process that prints such stacks. It describes large machines printing 20 stacks of eight acetabular cups for hip implants, or 160 cups per build.
EBM is not support-free, though. Colibrium's Spectra L page says its supports are used mainly to even out heat, and Desktop Metal cautions that EBM still needs thermal supports in many designs. Desktop Metal also notes that both processes need skilled machine preparation between builds, including cleaning and component changes, which usually takes about 2 to 3 hours.
Surface finish and detail
LPBF generally gives finer surfaces and features. In Pasang's comparison, as-built Ti-6Al-4V measured about 6 to 8 µm Ra from the laser process and 18 to 23 µm from EBM, which the authors attribute mainly to EBM's coarser powder and partly melted particles stuck to the surface. Layers were about 30 µm thick for the laser samples and 50 µm for EBM. EOS lists 9 to 12 µm Ra as built for its Ti64 parameter set with 30 µm layers.
Colibrium acknowledges that laser machines have traditionally finished better and that features below about 200 microns are harder for EBM because the beam broadens. It says its newer Point Melt scanning strategy improves surface quality. The coarser powder has an upside: Colibrium says EBM powders cost up to 50 percent less than finer powders and are easier and safer to handle.
Materials and properties
LPBF covers far more alloys. For its M 290 alone, EOS lists aluminum alloys, stainless, maraging and tool steels, cobalt-chrome, copper and copper alloys, nickel alloys such as IN718 and IN625, and several titanium grades. Commercial EBM lists are shorter. Colibrium offers its Spectra L in two Ti-6Al-4V grades, while the higher-power Spectra H adds titanium aluminide, cobalt-chrome and a highly alloyed tool steel. Colibrium highlights titanium aluminide turbine blades, which it says GE has printed by the thousands each year since 2019. It also notes that pure copper absorbs only about 2 to 10 percent of a red laser's energy but 65 to 85 percent of an electron beam's. Laser makers answer with more power: EOS launched a 1 kW version of the M 290 in 2024, qualified for pure copper and CuCrZr.
The thermal history shows in the properties. Pasang and colleagues found martensite in as-built laser Ti-6Al-4V and an alpha-beta lath structure in EBM, with the laser parts slightly stronger in every direction: 950 to 1,036 MPa ultimate tensile strength against 800 to 847 MPa for EBM, with comparable ductility. Both had some porosity. For comparison, EOS's Ti64 data sheet reports 1,055 to 1,075 MPa for laser-built specimens after heat treatment at 800 °C for two hours in argon. Pasang and colleagues note that laser parts are often heat treated, and cite other studies in which hot isostatic pressing removed the directional differences.
| Factor | LPBF (DMLS or SLM) | EBM (EB-PBF) |
|---|---|---|
| Energy source | Fiber laser; the EOS M 290 uses one 400 W laser | Electron beam; Colibrium lists 4.5 kW and 6 kW machines |
| Build atmosphere | Inert gas, such as argon in EOS's Ti64 process | Vacuum with a small, controlled helium flow |
| Powder bed temperature | Ambient in Pasang's study | About 700 °C for Ti-6Al-4V (Pasang); 1,000 °C or more (Colibrium) |
| Residual stress | High; stress relief at 400 to 800 °C, per Desktop Metal | Low; Colibrium says no stress relief is needed |
| Supports | Structural and thermal, often cut off by wire EDM or milling | Mainly thermal; parts can be stacked |
| As-built roughness, Ti-6Al-4V | About 6 to 8 µm Ra (Pasang); 9 to 12 µm Ra (EOS) | About 18 to 23 µm Ra (Pasang) |
| Materials | Broad range of aluminum, steel, nickel, cobalt, titanium and copper alloys | Conductive metals only; mainly titanium alloys, TiAl, nickel alloys, CoCr, tool steel and copper |
| Example build volume | 250 × 250 × 325 mm (EOS M 290) | Ø350 × 430 mm (Colibrium Spectra L) |
At a glance
Strengths
- Choose LPBF for fine features, smoother as-built surfaces and the widest range of qualified alloys
- Choose LPBF for aluminum, maraging steel and the many other alloys offered on machines such as the EOS M 290
- Choose EBM for crack-prone alloys such as titanium aluminide, per Colibrium
- Choose EBM for stacked batches of small titanium parts, such as hip implant cups
Limitations
- LPBF: residual stress means parts need supports and stress relief
- LPBF: support removal often requires wire EDM or milling
- EBM: rougher surfaces and coarser minimum features
- EBM: conductive materials only, and a shorter commercial alloy list
Typical applications
- LPBF: aerospace, automotive, medical, tooling and turbomachinery parts, per EOS
- EBM: porous titanium acetabular cups for hip implants
- EBM: titanium aluminide low-pressure turbine blades
- LPBF: copper parts on high-power machines such as the 1 kW EOS M 290
Materials for this process
- Ti-6Al-4V titanium
- AlSi10Mg aluminum
- Nickel alloy 718
- Nickel alloy 625
- Cobalt-chromium alloy
- Copper
- CuCrZr copper alloy
- 316L stainless steel
- 17-4 PH stainless steel
- Maraging steel
Common questions
Why does EBM need a vacuum?
Colibrium explains that collisions with gas molecules would drain the electrons' energy before the beam reached the powder, so EBM runs in a vacuum of about one-billionth of an atmosphere. A small, controlled flow of helium is added to stop electric charge from building up in the powder.
Are EBM parts free of residual stress?
Much lower in stress, according to the sources. Pasang and colleagues note that the EBM powder bed sits above stress-relieving temperature, about 700 °C for Ti-6Al-4V. Colibrium claims its parts need no stress relief. Desktop Metal still describes thermal supports as necessary in many EBM designs.
Which process gives a better surface finish?
Laser. In Pasang's Ti-6Al-4V comparison, as-built roughness was about 6 to 8 µm Ra for the laser process and 18 to 23 µm for EBM, mainly because EBM uses coarser powder. Colibrium says its newer Point Melt strategy improves EBM surfaces.
Are SLM, DMLS and LPBF the same thing?
In current use, yes. EOS calls its DMLS process laser powder bed fusion, and Desktop Metal describes L-PBF as also commonly referred to as SLM or DMLS. All three mean a laser melting metal powder in an inert atmosphere.
Sources
- EOS Titanium Ti64 for EOS M 290 (30 µm) process data sheet EOS · Checked 2026-11-02
- Directionally-Dependent Mechanical Properties of Ti6Al4V Manufactured by Electron Beam Melting (EBM) and Selective Laser Melting (SLM) (Pasang et al., Materials, 2021) Materials (MDPI) via PubMed Central · Checked 2026-11-02
- Enabling Metal Additive Production Using Electron Beam Melting Technology (EBM Anthology) Colibrium Additive · Checked 2026-11-02
- Powder Bed Fusion Loughborough University Additive Manufacturing Research Group · Checked 2026-11-02
- Spectra H EBM Machine Colibrium Additive · Checked 2026-11-02
- The Ultimate Guide to Laser-Free Metal 3D Printing (binder jetting) Desktop Metal · Checked 2026-11-02
- Spectra L EBM Printer Colibrium Additive · Checked 2026-11-02
- EOS M 290 system data sheet EOS · Checked 2026-11-02
- EOS Launches its EOS M 290 1kW Metal AM System (March 14, 2024) EOS · Checked 2026-11-02
- DMLS Metal 3D Printing EOS · Checked 2026-11-02
An explainer synthesized from the cited references, not hands-on testing. Vendor names for processes are trademarks of their owners and are mapped to the ISO/ASTM 52900 families for orientation.