I'm getting a new slant bed lathe (either a Doosan Lynx or Haas ST-20).
Both have 20 HP. But they are direct drive and higher speed than I am used to.
Right now I use a geared flat bed CNC lathe. It only has 10 HP, but I always run it on low gear, never need to go past 450rpm.
At low gear, this flatbed produces a lot of torque. I don't have the exact values (its an old machine), but I can assure you it has more torque than what either Haas or Doosan list as their max torque. And at lower RPM too!
For example I have 8.625" OD SS316 part that I turn down to 7.975"
Using Kennametal cutting force calculator; 0.15" DOC, 0.013 ipr, 170 rpm = 202ftlb...
Clearly a slant bed can't do that heavy of a cut at low speed. So I definitely will need to change my feeds/speeds.
I'm not too familiar with "high speed, low DOC cutting" so I used Sandviks Toolguide as a starting point, this what they recommend:
0.08" DOC, 0.009" ipr, 332rpm = 125ftlb
That is still quite high. The Doosan lists 93ftlb max torque at 1125 rpm and the Haas is 150ftlb at 500 rpm.
I'm now beginning to realize that I can't have my cake and eat it too... I want the versatility of a slantbed, but it seems that I have much to do on my feeds/speeds and any high torque low speed slant bed is +$$$
Both have 20 HP. But they are direct drive and higher speed than I am used to.
Right now I use a geared flat bed CNC lathe. It only has 10 HP, but I always run it on low gear, never need to go past 450rpm.
At low gear, this flatbed produces a lot of torque. I don't have the exact values (its an old machine), but I can assure you it has more torque than what either Haas or Doosan list as their max torque. And at lower RPM too!
For example I have 8.625" OD SS316 part that I turn down to 7.975"
Using Kennametal cutting force calculator; 0.15" DOC, 0.013 ipr, 170 rpm = 202ftlb...
Clearly a slant bed can't do that heavy of a cut at low speed. So I definitely will need to change my feeds/speeds.
I'm not too familiar with "high speed, low DOC cutting" so I used Sandviks Toolguide as a starting point, this what they recommend:
0.08" DOC, 0.009" ipr, 332rpm = 125ftlb
That is still quite high. The Doosan lists 93ftlb max torque at 1125 rpm and the Haas is 150ftlb at 500 rpm.
I'm now beginning to realize that I can't have my cake and eat it too... I want the versatility of a slantbed, but it seems that I have much to do on my feeds/speeds and any high torque low speed slant bed is +$$$