Microtool coatings using magnetron sputtering

Abstract

<title/>This paper presents a deposition process for hard coatings on micromachining cutting tools using closed field unbalanced magnetron sputter ion plating. Any microtools with diameters in the range 0·1-0·5 mm can be coated using this deposition method, with uniform, smooth and ‘defect free’ surface morphology on the cutting corner areas. The coatings, consisting of single or multiple transition metal nitrides or carbonitrides, have also been deposited on the flat, hardened tool steel samples and are shown to have the desirable properties of high hardness, good adhesion and high wear resistance. Evaluation of the coatings and coated microtools is carried out using scanning electron microscopy, microhardness, Rockwell diamond scratch and indentation, and pin-on-disc measurements. Mechanical micromilling is used to test the coatings on WC-Co solid micromills, dry cutting hardened H13 die steel. The results show that this deposition process is capable of producing a range of hard coatings on micromachining tools, with attractive properties and significant improvement of tool lifetime.