Achtung:

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Lattice structure tensile specimen manufactured with laser melting (LM) process out of the material H13. Show image information
Industry partners of the DMRC. Show image information
Quality control during a Laser Sinter (LS) build job by a researcher of the DMRC. Show image information
Fused Deposition Modeling (FDM) process during the manufacture of an Ultem 9085 part. Show image information
Additive manufactured reaction wheel bracket for telecomunication satellites. Show image information
Employees of the DMRC working with the "freeformer" from Arburg. Show image information
Tactile measurement of a SLM part with a Coordinatemeasuring machine (CMM). Show image information

Lattice structure tensile specimen manufactured with laser melting (LM) process out of the material H13.

Industry partners of the DMRC.

Quality control during a Laser Sinter (LS) build job by a researcher of the DMRC.

Fused Deposition Modeling (FDM) process during the manufacture of an Ultem 9085 part.

Additive manufactured reaction wheel bracket for telecomunication satellites.

Employees of the DMRC working with the "freeformer" from Arburg.

Tactile measurement of a SLM part with a Coordinatemeasuring machine (CMM).

Surface Topography Analysis and Enhancement of Laser Sintered Parts

3D Measurement of a surface topography of a laser sintered part surface. Adhered incomplete molten particles are obvious

The first part of the project includes the investigation of diverse existing methods to characterize the surface quality and their applicability to assess laser sintered parts. For characterization of laser sintered parts it is important to keep in mind imperfections at different levels of scale: shape deviations, surface deviations (e.g. waviness, terrace formation) and surface roughness (ranging from sub-millimeter to micrometer scale). Tactile and optical measurement systems are investigated as well. As an optical instrument fringe light projection is investigated and evaluated. Main emphasis is on suitable mathematical methods to extract valid information about surface defects on different scales from obtained data.

Left: untreated laser sintered sample; Right: sample treated with ceramic abrasives in mass finishing process

Another challenge is to get comparable information from completely different measurement techniques. Further on a subjective assessment of the surface quality by haptic testing is aimed at. For this purpose suitable test specimens are used and assessed through blind-testing by different test persons. Finally, we aim to get a correlation of subjective and objective assessment of different surfaces. The resulting surface quality for different machine parameters (e.g. layer thickness, laser and scanning parameters) and powder quality (virgin powder vs. used powder) is tested with the methods developed previously. Especially the orientation of a surface in respect to the layer orientation has a huge influence on the surface quality, too.

The post process is an important factor using the laser sintering process. In this part of the project the post process regarding the different post process parameter shall be investigated. For example at shot blasting the blasting time, the blasting distances as well as the blasting pressure are the most important parameters. Further on the blasting material shall be investigated as well. Next to the abrasive blasting method other promising methods like grinding and chemical etching will be used. The challenges here are also to find the right materials and parameters. Because of a lower surface quality, compared to injection molding, laser sintered parts are not used in visible areas of the manufacturing fields at the moment. The main focus is on a smoother surface with a minimal effort of manual labor.

The last part of the project deals with the ageing of post processed and untreated parts. Therefore the test specimens will exposed to light, humidity and temperature for different durations under laboratory conditions as well exposure to nature conditions. On one side the ageing will be simulated with a defined exposure of above mentioned impacts and then compared to ageing by real weather of Paderborn. Measurements will be done to evaluate the influences on surface quality.

Further project information
Project statusIn progress
Project duration24 month
Funding50 % Land of North Rhine-Westphalia
50 % DMRC industry partner
Project managerProf. Dr.-Ing. Hans-Joachim Schmid
Project coordinator Peter Keller (EOS GmbH)
Wolfgang Diekmann (Evonik Industries AG)
Hans-Ulrich Büse (Blue Production Company)
Scientific staffM.Sc. Patrick Delfs
Involved chairsParticle Technology Group (PVT)
Contact

Prof. Dr. Hans-Joachim Schmid

Partikelverfahrenstechnik (PVT)

Lehrstuhlleiter

Hans-Joachim Schmid
Phone:
+49 5251 60-2404
Phone:
05251 60 2410
Fax:
+49 5251 60-3207
Office:
E3.319
Web:

Office hours:
n.V.

Patrick Delfs, M.Sc.

DMRC

Surface Quality Laser Sintering

Patrick Delfs
Phone:
+49 5251 60-5419
Fax:
+49 5251 60-5409
Office:
W2.105
Web:

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