The cutting properties and wear of the knives with DLC and W-DLC coatings, deposited by PVD methods, applied for wood and wood-based materials machining

Purpose: Performance of DLC and W-DLC coated woodworking knives was investigated. The results of testing DLC and W-DLC coating properties as well as the results of life-time tests in the form of wear of HSS and HM knives with these coatings is presents.Design/methodology/approach: DLC coating was deposited by MCVA method, and W-DLC coating was deposited by pulsed RMS. Tests of knives coated with DLC and W-DLC as uncoated ones was made by machining: MDF board, pinewood slats and floorboard - using a typical industrial milling machine.Findings: DLC coating is significantly harder (33-40 GPa) than W-DLC coating (19 GPa). From Rockwell test it can be concluded that both coatings display high adhesion (HF1), whereas in the scratch methods, significantly lower adhesion of DLC coating can be observed (LC2 = 17-21 N) in comparison to W-DLC coating (LC2 = 54 N). Influence of the hardness and adhesion of coatings on wear resistance of coated tools is discussed.Practical implications: Wear resistance of planer knives coated with DLC is by approx. 20%, and W-DLC by approx. 30% higher in comparison with uncoated knives during MDF milling. Wear of planer knives with W-DLC coating is approx. by 10%, and DLC by approx. 25% lower in comparison to uncoated HSS knives during pinewood milling. Lifetime of HM shape tools coated DLC and W-DLC is considerably higher (200-300 %) during floorboard milling.Originality/value: The industrial tests of cutting wood and wood-based materials indicate that the carbon coatings deposited on the tool generally improve its performance and all wear indexes for the tools are lower than for uncoated. The DLC and W-DLC coatings show good antiwear properties required in industry application.