SLM vs DMLS: A Complete Comparison

3D metal printing has changed how industries design and manufacture parts, and two names you’ll always hear are SLM (Selective Laser Melting) and DMLS (Direct Metal Laser Sintering). Whether you’re choosing a production route or just trying to understand the difference between SLM vs DMLS, this guide breaks everything down in the exact pattern you like: clear intro, “what is” sections, how it works, advantages & limitations, deep comparison (quality, strength, speed, materials), use-cases, a side-by-side table, and FAQs.

This detailed comparison will help you decide which technology  SLM vs DMLS  fits your part requirements and budget.

What is SLM 3D Printing?

SLM 3D printing (SLM) is a powder-bed fusion (PBF) metal 3D printing technology that uses a high-energy laser to fully melt pre-alloyed metal powder into a molten pool that solidifies into dense, metallurgically bonded layers. SLM aims for near-full density and excellent mechanical properties, making it popular for aerospace, medical, and high-stress application.

How SLM Works

• A thin, uniform layer of pre-alloyed metal powder (e.g., Ti-6Al-4V, stainless steels, IN718) is spread across the build plate.

• A focused, high-power laser scans and completely melts the powder in the regions defined by the CAD cross-section.

• After one layer is fused, the build plate lowers, a new powder layer is spread, and the cycle repeats until the part is built.

Advantages of SLM

• Produces very high density (>99% in many cases) and excellent mechanical strength.

• Near-wrought properties possible with correct parameter control.

• Great for high-performance end-use parts and critical applications.

Limitations of SLM

• Equipment and process control are expensive and complex.

• Higher residual stresses (because of full melting) needs careful scan strategies and heat treatment.

• Limited to high-quality, pre-alloyed powders (material costs higher).

What is DMLS 3D Printing?

Direct Metal Laser Sintering (DMLS) is also a powder-bed fusion method for metals, historically described as sintering-based, but in practice many modern DMLS systems use energy levels that produce partial or near-complete melting depending on materials and parameters. DMLS is widely used for complex metal parts, tooling, and medical components.

How DMLS Works

• A metal powder layer is spread across the build platform.

• A laser (often somewhat lower power than SLM setups) selectively sinters or partially fuses powder particles together where the CAD model requires.

• Repeat layer-by-layer until the part is complete; parts are then removed and post-processed (heat treatment, HIP, machining as needed).

Advantages of DMLS

• Better material flexibility in some implementations (works well with complex alloys).

• Can achieve very good mechanical properties with optimized parameters and post-processing.

• Strong track record for tooling, small-batch production, and medical implants.

Limitations of DMLS

• Historically may show more porosity if parameters are not optimized (but modern systems mitigate this).

• Surface finish and density can vary with material and machine; post-processing often required.

SLM vs DMLS: Detailed Comparison

Now let’s compare both side by side.

SLM vs DMLS Core Technology

SLM:

• Fully melts metal powder

• Creates single-phase, high-strength solid metal

DMLS:

• Sintering + partial melting

• Designed for alloy-based metals

SLM vs DMLS Material Compatibility

SLM Materials:

• Pure metals: Titanium, Aluminum, Stainless steel

• Produces extremely dense parts

DMLS Materials:

• Alloy metals: Tool steel, Inconel, Maraging steel, Cobalt chrome

• More variety for industry tooling

If someone asks are SLM and DMLS the same, this is the biggest difference.

SLM vs DMLS Mechanical Properties

SLM:

• Higher density

• Higher tensile strength

• Ideal for aerospace loads

• Very stable crystal structure

DMLS:

• Alloy-based strength

• Excellent impact resistance

• Great for industrial tooling

Both processes produce strong parts but for pure metals, SLM wins.

SLM vs DMLS Surface Finish

SLM:

• Slightly smoother surfaces

• Better melt pool stability

DMLS:

• Slightly rougher

• Usually needs machining

SLM vs DMLS Dimensional Accuracy

Both SLM and DMLS deliver high accuracy, but SLM is marginally better due to complete melting.

Cost & Speed

SLM:

• Higher cost

• Slower due to deep melting

DMLS:

• More cost-efficient

• Faster layer cycles

Are SLM and DMLS the Same?

Short answer: Almost but not exactly.

• Technology base is the same: Powder bed + laser

• Results are similar: Industrial-grade metal parts

• But the core process differs:

  • SLM fully melts metal

  • DMLS sinters metal

So they are related but not identical.

SLM vs DMLS for Industrial Use

Choose SLM if you want:

• 100% density

• Pure metals

• Highest strength

• Aerospace-grade properties

Choose DMLS if you want:

• Alloy materials

• Functional mechanical parts

• Cost-efficient metal printing

• Industrial tooling solutions

SLM vs DMLS: Side-by-Side Table