Laser Melting (LM)

image of Explanation of the technology laser melting (same as direct metal laser sintering, DMLS, selective laser melting) including characteristics, materials, machines, vendors, applications and process chain. image of Explanation of the technology laser melting (same as direct metal laser sintering, DMLS, selective laser melting) including characteristics, materials, machines, vendors, applications and process chain.

Synonyms

Selective Laser Melting, SLM, Direct Metal Laser Sintering, DMLS, Laser Cusing

Process description

A thin layer of metal powder is selectively melted by a laser. The parts are built up layer by layer in the powder bed. Read more

A laser melting machine distributes a layer of metal powder onto a build platform, which is melted by a laser (or multiple lasers). The build platform will then be lowered and the next layer of metal powder will be coated on top. By repeating the process of coating powder and melting where needed, the parts are built up layer by layer in the powder bed.

Laser melting requires support structures, which anchor parts and overhanging structures to the build platform. This enables the heat transfer away where the laser is melting the powder. Therefore it reduces thermal stresses and prevents wrapping. The build envelope can be filled by several parts being built in parallel as long as they are all attached to the build platform.

Advantages / disadvantages

Laser melting can manufacture parts in standard metals with high density, which can be further processed as any welding part. However, the technology is rather slow and expensive as well as surface finishes are limited. Read more

The technology manufactures parts in standard metals with high density (above 99%) and good mechanical properties (comparable to traditional production technologies). A constantly widening set of standard metals is available. Parts can be further processed as any welding part.

LM is still an expensive and slow process. Tolerances and surface finishes are limited, however they can be improved through post-processing.

Application areas

  • Prototypes are produced in standard metals for form / fit and functional testing by laser melting
  • Support parts (jigs, fixtures, helps) are produced in standard metals
  • Small series parts down to one of a kind are directly produced in standard metals (further post-processing might be required to improve surface or tolerances)
  • Tools for injection molds are produced in hot work steel enabling conformal cooling (complex cooling channels directly beneath the surface

Characteristics / restrictions

  • Maximal build envelope: 600x400x500 mm3
  • Minimum feature size: 0.04-0.2 mm
  • Accuracy: +/- 0.05-0.2 mm (+/- 0.1-0.2%)
  • Minimum layer thickness: 0.03 mm
  • Typical surface finish: 4 – 10 microns RA
  • Density: Up to 99.9%

Characteristics are only indicative, as there are different types of machines available.

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Process chain

When planning the build, critical tolerances, surface finishes and overhangs need to be taken into consideration. After the build, parts often need to be thermally processed and the support structures need to be mechanically removed. Laser melting parts can be further post-processed as any welding part. Read more

Pre-build planning

The production of parts is planned in a build preparation software. One or several parts are placed in the build, using the digital 3D files (typically in the STL file format). Important decision during the set-up phase is the orientation of the part in the build envelope and what support structures are required. This depends on:

  • Geometry, overhangs and inclination
  • Location of most critical tolerances and surface finishes
  • Areas where post-processing is required and potentially additional material needs to be added

Post-processing

  • Removal of build envelope: The build envelope is removed from the machine
  • Remove powder: Build platform with the parts attached is taken out of the loose powder. Excess loose powder is removed by sand blasting. This is usually straight forward, however might require some extra effort for parts with complex geometric features (e.g. trapped powder)
  • Thermal processing: After the build, parts are often thermally processed to release residual stresses and improve part characteristics and metallurgical structure. Which regime is best depends on the application, desired part characteristics, the material used and the part characteristics. Typical processes include vacuum heat treatment, heat treatment under inert gas or hot isostatic pressing (HIP).
  • Removal of supports and post-machining: Afterwards, parts are taken off the build platform, typically through wire cutting EDM or machining. Further support structures are mechanically removed. Parts might be partially post-machined in order to fulfil critical tolerances.
  • Surface finish: Often parts need to be further processed to improve surface finish – either mechanically (e.g. polishing, grinding, peening) or chemically (e.g. plating, electro polishing).

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Materials

Copper-based alloys
Gold
 
Silver
 
Plastic
PA 12

Equipment

Vendor

Model

3D Micro Print

DMP50GP
DMP60GP

3D Systems

Phenix PSM Dental
Phenix PXL
Phenix PXM
Show All
Phenix PXS
Phenix PXS Dental
ProX 300
sPro 125 Direct Metal
sPro 250 Direct Metal

Additive Industries

MetalFAB1

Concept Laser

M1 Cusing
M2 Cusing
M2 Cusing Multilaser
Show All
M3 Linear
Mlab Cusing
Mlab Cusing R
X line 1000R
X line 2000R

EOS

EOSINT M 270
EOSINT M 280
M 100
Show All
M 290
M 400
Precious M 080

Optomec

LENS 450
LENS 850-R
LENS MR-7

ReaLizer

SLM 100
SLM 125
SLM 250
SLM 50

Renishaw

AM 125
AM 250

Sisma

MySint 100
MySint 300

SLM Solutions

SLM 125 HL
SLM 250 HL
SLM 280 HL
SLM 500 HL

TRUMPF

TruPrint1000

Stay up-to-date on professional 3D printing!


Our monthly newsletter contains ideas, how you could use 3D printing in your company. See what projects other companies are realising and stay up-to-date what’s new in professional 3D printing and on Additively.

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