Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

3D characterization of powder gas stream improves process quality in laser material deposition

26.04.2012
For the first time, scientists at the Fraunhofer Institute for Laser Technology ILT have succeeded in performing qualitative and quantitative characterization of the powder gas stream in laser deposition welding.
The powder gas feed is an important parameter of the overall process and plays a key role in the results achieved. Precise knowledge of the powder gas stream is therefore necessary to maintain process quality.

Laser material deposition has become an established processing technique for the repair and manufacture of metal parts and the functionalization of metal surfaces. A nozzle is used to inject a powdered filler material into the melt generated by the laser beam. This produces a layer which is metallurgically bonded to the workpiece. The delivery of powder to the melt pool via the nozzle is a crucial element in this process. It has a major influence on the consumption of powder material, the effectiveness of the gas shielding system used to prevent oxidation, and the quality of the coating layer. In order to ensure consistently high process stability and quality, it is necessary to check the processing results at regular intervals.
This is because nozzle wear can lead to deviations that cause changes in the diameter and position of the powder focus. Orientation of the powder gas stream to the laser beam is of major importance. Until now, the only way of determining these changes was to use laser metal deposition to obtain reference samples. Correlating these samples with comparative deposited welds revealed the quality of the nozzle.

A simpler method of checking nozzle quality

A team from the Fraunhofer ILT has now developed a measurement procedure for characterizing the powder gas stream which provides a simple and reproducible means of checking nozzle quality. The process involves illuminating the powder gas stream from the side with a laser beam and using a camera positioned coaxially to the nozzle to capture images of the powder gas stream through the nozzle. This makes the ring-shaped distribution of the powder visible. Thanks to the camera's high frame rate, it is possible to precisely determine the number and position of individual powder particles at a defined point in time. Based on similar principles to laser caustic measurement, the lateral laser beam moves down the powder gas stream layer by layer, requiring just a few seconds to capture the data for each layer. The system then calculates the particle density distribution for each layer from the several thousand individual images captured by the camera. Finally, the individual layer images are superimposed on each other to yield the overall spatial particle density distribution. “For the first time, we have succeeded in developing a measuring procedure that enables us to determine the constancy of the powder mass flow, the symmetry of the powder gas stream, and the position and size of the powder focus,” says Stefan Mann, who is in charge of the project at the Fraunhofer ILT. Potential applications of this new measuring technique include all activities in the field of laser deposition welding, in particular engine and power plant manufacturing, toolmaking and mechanical engineering.
Live demonstration of the measuring process

A demonstration of this measuring procedure will be held in the Fraunhofer ILT’s laser equipment facility in Aachen on May 11 as part of the “Laser Technology Live” event at the International Laser Technology Congress AKL’12. To find out more, please visit www.lasercongress.org

Your contacts at Fraunhofer ILT
Our experts are on hand to answer your questions:

Dip.-Ing. Stefan Mann
Process Control and System Technology
Phone +49 241 8906-321
stefan.mann@ilt.fraunhofer.de

Dipl.-Ing. Peter Abels
Head of Process Control and System Technology
Phone +49 241 8906-428
peter.abels@ilt.fraunhofer.de

Fraunhofer Institute for Laser Technology ILT
Steinbachstrasse 15
52074 Aachen
Phone +49 241 8906-0
Fax +49 241 8906-121

Axel Bauer | Fraunhofer-Institut
Further information:
http://www.ilt.fraunhofer.de

More articles from Process Engineering:

nachricht Dresdner scientists print tomorrow’s world
08.02.2017 | Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS

nachricht New technology for mass-production of complex molded composite components
23.01.2017 | Evonik Industries AG

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>