Laser Treatment CVD Diamond Coated Punch for Ultra-Fine Piercing of Metallic Sheets

Abstract

CVD-diamond coated special tools have been widely utilized to prolong their tool life in practical production lines. WC (Co) punch for fine piercing of metallic sheets required for high wear-toughness to be free from chipping and damages and for high product quality to punch out the holes with sufficient dimensional accuracy. The laser trimming process was developed to reduce the surface roughness of diamond coating down to submicron level and to adjust its diamond layer dimensions with a sharp punch edge for accurate piercing. The pulsed laser irradiation was employed to demonstrate that micro-groove was accurately formed into the diamond coating. Less deterioration in the worked diamond film by this laser treatment was proved by the Raman spectroscopy. The femtosecond laser trimming was proposed to sharpen the punch edge down to 2 μm and to form the nano-textured punch side surfaces with the LIPSS (Laser Induced Periodic Surface Structuring)-period of 300 nm. Fine piercing experiments were performed to demonstrate that punch life was significantly extended to continuous punching in more than 10,000 shots and that mirror-shining hole surfaces were attained in every shot by regularly coining the nanotextures. The sharp punch edge with homogeneous edge profile was responsible for reduction of the induced damages into work sheet by piercing. The punch life was extended by the ejection mechanism of debris particles through the nanotextures on the punch side surface. The present laser treatment was useful in trimming and nanostructuring the complex-shaped punch edge for industrial application.

Galling-free fine blanking of titanium plates by carbon-supersaturated tool steel punch

“…As reported in [21][22], the abrasive and adhesive galling processes were effectively suppressed by the nanotexturing onto the punch side surface when punching out the electrical steel sheets. This was because the debris particles were ejected through the nanotextured grooves to the outside of punching process.…”

Femtosecond Laser Micro-/Nano-Texturing to Die Substrates for Fine Imprinting to Products

“…In the case of laser-texturing of the glassy carbon, this removal rate under the same laser irradiation condition decreased down to 5-10 μm. On the other hand, the sp3-rich DLC and the diamond coatings needed more irradiation shots for drilling the depth of coatings [29]. This dependency on the mass density of carbon base coatings reveals that the power and fluence of laser irradiation must be tuned to each substrate materials.…”