Superfast Stripping of DLC Coatings from WC-Co Cutting Tools Using a Low-Energy High-Current Electron Beam

Diamond-Like Carbon (DLC) coatings are extensively applied to enhance the durability and cutting efficiency of Hard Metal (HM) cutting tools, particularly under demanding operating conditions. Over time, these tools inevitably develop defects and wear, requiring their disposal. To extend their lifespan through resharpening and reuse, an efficient decoating process is essential. In the present research, a vacuum plasma technology is implemented to tackle the issue of cutting tools decoating, with an eye on avoiding the use of harmful chemicals in the process. Low-Energy High-Current Electron Beam (LEHCEB) was employed to remove DLC coatings from WC-Co2 milling inserts. Pulsed irradiation by LEHCEB allows to completely evaporate the carbon coating from the substrate by exploiting the fast (109 K/s) induced thermal gradient and the lowered sublimation point of the coating at the vacuum working pressure. The electron accelerating voltages were 20, 25 and 30 kV, with an associated energy density of 2.5, 3.3 and 4.9 J cm-2, respectively. The number of pulses were 5, 10 and 20, with a 0.2 Hz repetition frequency. The working pressure (1.8·10-4 Torr) and the ionized gas (Ar) were kept the same. Stripped substrates were then reground, recoated and tested to demonstrate the full regeneration of the cutting tools.