Methods of making a drilling tool with low friction coatings to reduce balling and friction

A method of manufacturing a drilling tool comprising:

• providing one or more drilling tool components with specified locations for fitting cutters, inserts, bearings, rollers, additional non-coated components, or combinations thereof;
• cleaning said one or more drilling tool components with specified locations to remove oil, organic compounds, and/or adsorbates;
• applying masking to said cleaned specified locations for fitting cutters, inserts, bearings, rollers, additional non-coated components or combinations thereof;
• applying a multi-layer low friction coating to said cleaned specified locations, wherein said multi-layer low friction coating comprises:
• i) an under layer selected from the group consisting of CrN, TiN, TiAlN, TiAlVN, TiAlVCN, TiSiN, TiSiCN, TiAlSiN and combinations thereof, wherein the under layer ranges in thickness from 0.1 to 100 μm,
• ii) an adhesion promoting layer selected from the group consisting of Cr, Ti, Si, W, CrC, TiC, SiC, WC, and combinations thereof, wherein the adhesion promoting layer ranges in thickness from 0.1 to 50 μm and is contiguous with a surface of the under layer, and
• iii) a functional layer selected from the group consisting of a fullerene based composite, graphene, a diamond based material, diamond-like-carbon (DLC), and combinations thereof, wherein the functional layer ranges from 0.1 to 50 μm and is contiguous with a surface of the adhesion promoting layer.
• wherein the adhesion promoting layer is interposed between the under layer and the functional layer,
• wherein the coefficient of friction of the functional layer of the low friction coating as measured by the block on ring friction test is less than or equal to 0.15, and
• wherein the abrasion resistance of the low friction coating as measured by the modified ASTM G105 abrasion test yields a wear scar depth of less than or equal to 20 μm and a weight loss less than or equal to 0.03 grams;
• removing the masking from said cleaned and coated specified locations of said one or more drilling components;
• inserting cutters and inserts and assembling moving parts to the cleaned and coated specified locations of the one or more drilling tool components;
• and
• assembling the one or more drilling tool components to form a drilling tool.