23 April 2010

Concept Laser presents a quality management system for real-time monitoring of the LaserCUSING® process

Concept Laser’s holistic approach to Quality Management expands the boundaries for direct component production and enhances traceability for the aviation and medical sectors.

Applications in the medical and aviation sectors demand a high degree of quality control and process monitoring with the aim of achieving a zero-defect standard. To meet these stringent requirements, Concept Laser has developed a completely new type of QM system for real-time monitoring of the LaserCUSING® process, also known as Selective Laser Melting (SLM).

The core of this new development is a user-friendly evaluation of the process data which can in turn, be adapted to fulfil the documentation requirements of customers. Each of the individual monitoring systems used previously, have now been brought together and improved in order to enhance the level of reproducibility. Concept Laser’s pilot partner in this venture is the German Aerospace Centre (DLR), which is based in Cologne (Germany). The "Engineering Systems House" division at the DLR use the Concept Laser process to carry out research on turbine components and other metal applications in aircraft construction.

Microscopic real-time monitoring of the melt-pool

The new QM package includes real-time monitoring of the melt pool to monitor the construction process at a microscopic level. LaserCUSING® is a micro-welding process working in a confined area (track width approx. 100 µm), building with a layer thickness of approx. 20 – 50 µm, and generating high resolution detail on the component parts. The melt-pool module follows the ongoing construction process, sampling at the rate of several thousand scans per second and analysing the relevant data within the melt track in real time. This data is then further evaluated and documented by the machine software.

Continuous real-time QM modules
Concept Laser uses a detached powder module to ensure consistent powder quality for the LaserCUSING® process. Being separate from the production facility, the powder module allows sieving, through a fine sieve mesh of less than 50 µm, and recovery of the metal powder to take place in parallel with the construction process, providing higher throughput rates.

The powder module can also be made inert using a gas such as argon, thus eliminating oxygen and guaranteeing the constant chemical composition of the metal powder. Redundant monitoring and regulation of the oxygen concentration of the process gas takes place in the process gas module. In future, this will also include monitoring the condition of the filter with the additional possibility of automatic filter cleaning. A temperature module monitors important, temperature-sensitive machine components and provides information about their current state. Finally, the documentation module, as one element of the LaserCUSING® software, analyses the ongoing construction process and makes it possible to provide reports on all of the data held within the real-time QM modules.
Stochastic structure based on the "island principle"

A fundamental core function of LaserCUSING® machines, is the exposure of individual layers based on the "island principle". The process has been patented and is unique. Stochastically selected, the segments of a layer (so-called "islands") are processed successively. In the melting process, this strategy guarantees a significant reduction in stresses within the finished component.

Expanding the boundaries for direct component production
The QM system used within Concept Laser’s range of machines is also able to monitor the production process when using extremely fine titanium powders, such as CL41 TI, satisfying the requirements of ASTM Standard F136 for surgical implants. Other materials such as high-grade steels, cobalt-chromium-base alloys or nickel-based super alloys are also used in the LaserCUSING® process. The use of precious metals, such as gold and silver is also in development.

With these latest achievements, Concept Laser has expanded the boundaries of feasibility for direct components made from metals and at the same time set new benchmarks when it comes to reproducibility and quality. Other machine manufacturers only document the laser fusing process at the macroscopic level, which covers the full field of construction. Concept Laser is consistently adopting the approach of analysing the level of quality in the process at the microscopic level during the production of tracks, with real time sampling rates in the kHz range. The use of finer powders also allows a significant enhancement in the level of surface finish that can be achieved. The high standards, in terms of quality and process reliability, in the fabrication of metal components using the LaserCUSING® process, now meet the very latest and most demanding specifications.

The Concept Laser range of LaserCUSING® machines are available from ES Technology Limited, who are responsible for the marketing, sales, servicing and support of the full range of Concept Laser products within the United Kingdom and Ireland.

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