Product Code: ICAL08_407

Laser Stripping of CrTiAIN Coating to Facilitate Re-use of Cutting Tools
Authors:
Marimuthu Sundar, The University of Manchester; Great Britain
D. Whitehead, University of Manchester; Manchester Great Britain
P. Mativenga, University of Manchester; Manchester Great Britain
Lin Li, University of Manchester; Manchester Great Britain
Y. Shicai, Teer Coatings Ltd.; Worcestershire Great Britain
K. Cooke, Teer Coatings Ltd.; Worcestershire Great Britain
Presented at ICALEO 2008

This work provides details on the use of laser material processing technology for selectively removing thin layer CrTiAlN coatings from steel substrate. CrTiAlN coating has a high hardness and oxidation resistance and finds application in cases such as cutting tools. The motivation for removal of such coatings is to enable reuse of coated hard metal tooling and hence promote sustainable material usage. Existing chemical-based striping methods have disadvantages such as uneven removal, poor surface finish, and production of waste residue as well as the associated environmental concerns. Laser stripping was performed using a KrF excimer laser at 248 nm wavelength. The effect of laser fluence, number of pulses, frequency, scanning speed and stepover distance on the stripping performance was investigated in detail. The coating stripping process was evaluated in terms of resulting surface quality and the ability to remove CrTiAlN without substantial damage to the substrate. Successful laser removal of CrTiAlN coating has been demonstrated. Elemental EDX analysis and cross sectional SEM back-scattered image confirms the complete removal of the CrTiAlN coating from steel substrate without damage to the steel substrate. The resulting surface roughness was found to be in the range of 400 nm Ra. Experimental observations support evaporation as an active mechanism for coating removal.