Cutting steel using diamond tools in micro machining

The scope and nature of national security and resilience is evolving rapidly, which is why the Middle East’s civil defence needs to have the right equipment to address all kinds of situations. The diamond tool is commonly used in micro-machining, as it can withstand the micro hardening of the work-piece surface during micro-machining of intricate, high-precision parts used in defence equipment. However, if a diamond tool was to be used to cut steel, one of the most common engineering materials used in defence industries, the diamond tool will face severe tool wear.

While diamond only softens at 1350 degree Celsius and melts at 3027 degree Celsius, and is also the hardest material in the world, it has a weakness. Diamond succumbs to graphitisation, which means that it will change its crystal structure to graphite crystal structure at 200 degree Celsius in the presence of a catalyst metal such as carbon steel and alloys with titanium, nickel and cobalt.

There have been various attempts to improve the tool life of the diamond tool, while cutting steel so as to improve the efficiency and profitability of this operation. Such processes include micro-cutting the steel workpiece in a carbon-rich gas chamber as well as a cryongenically cooled chamber. However, these methods require costly equipment modification and restrict direct supervision of the micro-cutting process.

The latest breakthrough came when the diamond tool was subject to ultrasonic vibration during micro-cutting. It has been shown that a diamond tool subject to ultrasonic vibration can cut the steel well enough to produce a mirror surface finish with acceptable tool life. The ultrasonic vibration at the diamond tool tip allows the tool face to cool down considerably during the cutting process and delays the chemical reaction between the diamond tool and the steel workpiece. As a result, the diamond tool life is increased by a few hundred times.

For example, a single crystal diamond tool with feedrate 5 micron/revolution, cutting speed zero to 5m/min and depth of cut 10 micron was attached to a ultrasonic vibration generator so that the diamond tool tip vibrated about 4 microns, while it was used to cut stainless steel. The mirror surface finish of the cut steel surface was measured at 8nm Ra. The tool life depended on the spindle speed of machine tool, as well as the amplitude and frequency of ultrasonic vibration to a large extent. Among the parameters, which affect the processing quality, cutting speed was utmost, followed by feed, and the influence of back cutting depth was insignificant.

With more and more machining companies moving into the niche micro machining field, such ultrasonic vibration assisted cutAdidas