A study on the accuracy of thermography-based temperature measurement in powder-fed directed energy deposition

Research output: Contribution to journalConference articleContributedpeer-review

Contributors

  • Christian Kledwig - , DMG MORI AG (Author)
  • Markus Hofer - , DMG MORI AG (Author)
  • Martin Reisacher - , DMG MORI AG (Author)
  • Frank Brückner - , Chair of Laser and Surface Technology, Institute of Manufacturing, Product and Production Development, Luleå University of Technology, TUD Dresden University of Technology, Fraunhofer Institute for Material and Beam Technology (Author)
  • Jens Bliedtner - , University of Applied Sciences Jena (Author)
  • Christoph Leyens - , Institute of Materials Science, Chair of Materials Technology, TUD Dresden University of Technology, Fraunhofer Institute for Material and Beam Technology (Author)

Abstract

Due to continuous development and increasingly deep understanding of the additive process, directed-energy deposition (DED) is becoming more and more interesting for industrial use. However, both the number of influencing factors and the process complexity, still require well-trained operators who can monitor and understand the machine tools. In order to facilitate the operators and to enable longer unattended processes, higher process safety, reliable monitoring systems and closed-loop controller are required. For example, despite a large number of investigations, the monitoring and control of the temperature distribution within the work piece still poses a big challenge. This study focusses on workpiece temperature measurement using a thermal imaging camera that observes the entire machining area. In order examine the measurement error caused by different viewing angles (φφ = 0 … 75°), object temperatures (TT = 333 … 1073K), surface conditions (welded and milled) and materials (316L, Inconel 718 and CuAl10) commonly used in DED, several approaches were followed using a thermal camera. It was found that surface condition and material cause the greatest measuring errors (up to +325K | − 453K). However, the measuring errors can be significantly reduced by suitable selection of the emissivity, so that it is possible to measure even the milled CuAl10 surface at a known viewing angle with a measuring error of +13.3% | − 10.9%.

Details

Original languageEnglish
Pages (from-to)35-41
Number of pages7
JournalProcedia CIRP
Volume95
Publication statusPublished - 2020
Peer-reviewedYes

Conference

Title20th CIRP Conference on Electro Physical and Chemical Machining, ISEM 2020
Duration19 - 21 January 2021
CityZurich, Online
CountrySwitzerland

Keywords

Keywords

  • Directed energy deposition, Laser cladding, Laser metal deposition, Process monitoring, Temperature distribution, Thermal imaging