More grazing tooth entry works better.
I have a question about this which was surely answered in "Machining 101", but I never took that class. I know that there are people here who have not just taken that class, but actually taught it, so I was wondering if one of them could set me straight.
My question is not about the gear train of the machine, but instead the effects of an interrupted cut on carbide cutters.
Think about two different ways of doing a cut, where the tool is wider than the cut. In the first way, the cutting edges have a grazing entry and an abrupt exit. In the second way, the cutting edges have an abrupt entry and a grazing exit.
In the first way, when the tooth enters the material, the chip is thin, so there is no shock on the tooth upon entry. The force or pressure build as the tooth moves through the material. Finally, when the tooth exits, the chip is thickest and so there is a sudden jump (downwards) in pressure on the tooth, as it exits.
In the second way, when the tooth enters the material, the chip is thick, so there is sudden shock as the force or pressure leap up. The force or pressure then decrease as the tooth moves through the material, because the chip is getting thinner. Finally, when the tooth exits, the chip is thinnest and the pressure on the tooth, just before it exits, is almost zero. So when the tooth does exit, there is no sudden downwards jump in pressure on the tooth.
In the first way, the shock on the tooth happens in tension, a large compressive force is suddenly released. In the second way, the shock on the tooth happens in compression, a large compressive force is suddenly applied. Now I always thought that carbide was a material like concrete: strong in compression, but weak in tension. If that's true, wouldn't the second approach preserve the cutting edges better than the first?
Cheers,
Bruce