Member postings for Richard Wright 1

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Well Novice,

I was a sales engineer and industrial cutting tool research engineer once upon a time and indeed it is for conventional right to left machining.

The gold colour is titanium nitride coating, very thin but what most people don't realise is that when it gets black it is still there improving the cutting action. It actually soaks back into the carbide substrate so don't chuck blackened ones away!

Unfortunately, tungsten carbide has the worst cutting edge of all tool materials i.e. microscopically it has a large radius compared to the best; diamond. Then from top (diamond) down: polycrystaline diamond, cermets, ceramics, silver steel,HSS....

TC Tungsten Carbide relies on high speed and HEAT to 'cut' so only really useful for heavy duty. Don't cool it with splashes of coolant either! Either FULL flood coolant or NON or you will introduce micro-cracking and ruin your tool!

HSS cutting tools and milling cutters tool-life can be increased 10 fold by dipping into liquid nitrogen over-night. Tested this myself scientifically.

Don't use pure diamonds or composite diamond tips on anything containing Carbon or you will ruin the diamond as it itself is composed of carbon under high pressures etc.

Use Cubic Boron Nitride to machine anything including TC at 80 Rockwell C! Use high speed, high pressure though until a swarf comes off red hot (400 M/min cutting speed; 0.1mm/rev feed) on hard steels and even hardened shafts and welds etc!

If you can't afford all these expensive 'exotic' tools, use good old HSS carefully ground (constant dipping to avoid softening while grinding) To achieve an excellent finish on steel parts, make a scrapper tool of HSS; normal looking right to left but with a flat at the front parallel with the lathe axis. Final scrape cut a few microns at a slow speed (feed less tha the width of the flat so get overlaps) for an excellent result.

Hope I've helped a bit?

Richard