Method of making cutting tool for aluminum work pieces having enhanced crater wear resistance

Reference Number: N 03-03

Inventors: Schmatz, Duane J.; Badgley, John S.; McHugh, Charles O.

Owner: NISTAC

USPTO Link: 4936959

Invention Summary

The invention, in one aspect, is a method of making an iron-based cutting tool useful for machining aluminum-based workpieces at surface speeds at or in excess of 1000 surface feet per minute (sfm). Such method comprises (i) removing surface impurities from the surface of the cutting tool which will be exposed to crater wear during the machining, the removal being by sputtering or ion bombardment using the surface as a target thereby resulting in a cleansed activated surface; and (ii) depositing a single-phase crystal film of sputtered silicon carbide onto the cleansed activated surface.

The activation of the surface in step (i) is preferably carried out by causing ionized argon to be accelerated against the surface maintained at about zero bias for a period of about 2-4 minutes; preferably, the depositing of step (ii) is carried out to cause silicon carbide to be condensed onto the activated surface as a result of being sputtered from a silicon carbide target for at least 300 minutes. Advantageously, the film of silicon carbide has a thickness in a range of about 1-4 microns, and the crystal orientation of such film is amorphous.

The invention, in another aspect, is a cutting tool for machining aluminum workpieces at surface speeds in excess of 1000 sfm, the tool having enhanced crater wear resistance. The tool comprises (a) a preshaped base of steel having a cutting edge defined by the juncture of flank and rake surfaces, and (b) a single-phase crystal film of sputtered silicon carbide coated onto at least the rake surface. Advantageously, the cutting tool has a crater wear resistance represented by a K value of less than 0.08 when measured at a distance of 0.03-0.045 inches from the cutting edge and viewed at an angle of zero or 30.degree. from the flank cutting edge.

Still another aspect of this invention is a new method of use, the use being for machining aluminum-based workpieces at high surface speeds exceeding 1000 sfm. The method of use comprises moving an iron-based cutting tool against an aluminum-based workpiece to continuously shear off a shaving of said workpiece, the cutting tool having a rake face contacted by the shaving, which face is coated with a single-phase crystal film of sputtered silicon carbide.