Originally Posted by
The Pininator
The reason I ask this is because I am looking at hundreds upon hundreds of programs done by at least three different programmers over a span of 6 or 7 years, and they are all done this way. While I think that I should be able to use typical turning feedrates in the example I mentioned above, this amount of history has me wondering....
Could be that the others have done what you are doing now (looking at exsisting programs), only they never asked if this is an optimal condition, but merely copied what they saw.
Cogsman1 outlined the typical situations that low feed would be appropriate.
You've stated that these are not the cases that you have, but again, alot of machines are programed by alteration rather than creation.
This practice does have the tendancy to perpetuate both good and bad practices.
I would say that with swiss machines that turning feeds are .0002-.0020" IPR.
There are many cases that you can increase beyond that but every situation is different and needs evaluated on its own.
At the risk of repeating Cogsman1, here are some low feedrate situations...
- Bar pushes back during turning operation
- Thinner chip is easier to control
- Bearing design lacks robust performance
- Tool holding lacks rigidity
- High depth of cut
- The use of tools with very small or nearly sharp tool nose radius
- Fine surface finish requirements
I would say that if you feel that a higher feedrate would work than give it a go.
If chip control and surface finish are good and the bar doesn't push back, that's good.
This should also increase tool life and reduce cycle time and those always make the bottom line better and that should make your boss happy.
HTH
Good luck.
Control the process, not the product!
Machining is more science than art, master the science and the artistry will be evident.