[The Pininator]

I have been messing around with some Tornos ENC-16 and ENC-164 machines lately. I have been learning by going through older programs and one thing I have noticed is the feed rates. Being a regular non Swiss turning kinda guy, they seem a little strange to me. I noticed that typically the feed rates are very slow. Many are in the.0008" per rev range for turning a .190" dia for example. In fact, it doesn't seem to matter what the diameter is, they range from .098" up to .625", the feed rates are always in this area. Is this normally the way these should be programmed and if so, could someone enlighten me to why? Is it something to do with guide bushings? The age of the machine? Any input is appreciated.

[cogsman1]

On a Swissmachine we are NOT doing any rough cuts so the feedrate you see is for the finish pass and gets adjusted for depth of cut and chip control. On occasion too great a feedrate with a deep cut can push the stock back also. Many swiss machines are doing medical parts out of Titanium which will catch FIRE if it gets too hot.

[The Pininator]

Thanks for the reply cogsman1.
Lets assume the DOC is minimal, .01"-.03" and it is not titanium but rather 17-4 stainless steel for example. Is there any reason for the feedrates to be at the .0008" per rev range?

[The Pininator]

Thanks for the reply cogsman1.
Lets assume the DOC is minimal, .01"-.03" and it is not titanium but rather 17-4 stainless steel for example. Is there any reason for the feedrates to be at the .0008" per rev range?

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....

[ProProcess]

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.

[The Pininator]

Thanks for the input. I'm going to start tweaking some of these programs a bit. If I see sparks or fire I will back off :-)