rake60
Well-Known Member
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- Jul 8, 2007
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OK I'm a tech geek. I find the how's and why's fascinating.
Take a look at chip formation in cutting steel.
If the feed is far too slow the cut will produce a heavy stringer chip.
It will be straw to blue in color and is a hazard to you as well as your tooling.
If the feed is moderately too slow the chip will break in the shape of a 6
(or 9 depending on your point of view.). That chip is breaking on the base material.
It is curling ahead of the tool and ripping surface of the base material that is left.
If the feed is too fast the chip will break in the same shape of a 6.
Now it's curling around and hitting the face of the tool. The surface finish looks good
but the tool is being hammered and will fail very soon.
Between those speed there is a perfect zone. The chip will break on it's self.
No damage to the surface OR the tool.
So what exactly is that perfect speed?
If I gave you a 14 foot long bar of 2" CR steel and you took 4" off the front end of that bar
and another 4" from the back end that perfect speed would be different.
The text books will tell you EXACTLY what speeds and feed to use.
Truth is there is no permanent perfect answer.
The metal will tell you all you need to know.
All you need to do is observe and listen to what it's telling you.
If it doesn't feel safe, it ISN'T!
Rick
Take a look at chip formation in cutting steel.
If the feed is far too slow the cut will produce a heavy stringer chip.
It will be straw to blue in color and is a hazard to you as well as your tooling.
If the feed is moderately too slow the chip will break in the shape of a 6
(or 9 depending on your point of view.). That chip is breaking on the base material.
It is curling ahead of the tool and ripping surface of the base material that is left.
If the feed is too fast the chip will break in the same shape of a 6.
Now it's curling around and hitting the face of the tool. The surface finish looks good
but the tool is being hammered and will fail very soon.
Between those speed there is a perfect zone. The chip will break on it's self.
No damage to the surface OR the tool.
So what exactly is that perfect speed?
If I gave you a 14 foot long bar of 2" CR steel and you took 4" off the front end of that bar
and another 4" from the back end that perfect speed would be different.
The text books will tell you EXACTLY what speeds and feed to use.
Truth is there is no permanent perfect answer.
The metal will tell you all you need to know.
All you need to do is observe and listen to what it's telling you.
If it doesn't feel safe, it ISN'T!
Rick
