Keeping an edge longer. (news & notes).

A Michigan manufacturer of stainless steel hexagonal valves has tripled its tool life and cut machine downtime by a third, by using tools made of a specialty alloy that approximates the wear resistance of carbide at less cost than carbide tools.

The parts manufacturer originally used dovetail form tools fashioned from T15 steel to make the small valves, which are turned in screw machines. T15 is a high carbon/tungsten/cobalt/vanadium alloy that offers both abrasion resistance and hardness. However, every eight hours, the form tools became worn, so that the company had to stop its screw machine and grind off 0.04 inch to sharpen them.

The part maker decided to increase productivity by extending the intervals between tool sharpening, and approached Nichols Precision Tool Inc. of Madison Heights, Mich., for a solution. Nichols is a manufacturer of high-speed steel and carbide cutting tools for screw machines and CNC machines.

Company president Dave Nichols ruled out tungsten carbide tools, whose relative brittleness might cause them to crack in this interrupted cut application. Instead, he suggested making the form tools from the Micro-Melt Maxamet alloy developed by Carpenter Specialty Alloys of Wyomissing, Pa.

Maxamet is composed of 2.15 percent carbon, 4.75 percent chromium, 6 percent vanadium, 13 percent tungsten, and 10 percent cobalt, with the balance being iron. This composition and the manufacturing process used by Carpenter to make bars or plates of the alloy give properties that lie between those of conventional high-speed tool steels like T15 and cemented tungsten carbide.

For example, the high carbide volume provides the alloy with wear resistance, while balancing the chemical composition when making the alloy enables the finished product to possess good toughness at high levels of hardness.

After the Maxamet forming tools were installed at the Michigan machine shop, workers were able to run their forming machine for 12 hours between resharpenings that only required 0.02 inch to be ground off the tools. The combination of longer machining runs and savings in stock removed from the tools added up to a 300 percent increase in tool life.

Nichols believes further improvements are possible using Maxamet. The precision toolmaker will coat future Maxamet form tools with titanium nitride and titanium carbonitride, hoping to double or even triple tooling life.