Cutting data for Threading

 
Cutting speed m/min.
(Ft/min) Tool grade
Material
PM25
KM15
TIN25
Low and medium carbon steel 120-80
(390-260)		   250-210
(820-690)
High carbon steel 110-70
(360-230)		   210-150
(690-490)
alloyed tool steel and heat-treatment steels 100-70
(360-230)		   180-140
(590-460)
Stainless steels 100-70
(360-230)
90-70
(295-230)
 140-110
(460-360)
Cast-iron HB 180-250  
90-70
(295-230)
  
Non-Ferrous metals  
180-120
(590-390)
  
 
Nº of passes
P mm
TPI
Nº of passes
0,50 48,0 4-6
0,75 32,0 4-7
1,00 24,0 4-8
1,25 20,0 5-9
1,50 16,0 6-10
1,75 14,0 7-12
2,00 12,0 7-12
2,50 10,0 8-14
3,00 8,0 10-18
3,50 7,0 11-18
4,00 6,0 11-18
4,50 5,5 11-19
5,00 5,0 12-20
5,50 4,5 12-20
6,00 4,0 12-20
8,00 3,0 15-24
General recommendations:

- Threading speeds should normally be a minimum of 80% to 90% of turning speeds being used to machine the same component. (Assuming grades are compatible).
-Check helix angle and number of passes shown in charts before starting.
- Ensure centre height is correct.
- When there is a problem consult the following recommendations and change only one variable at time. This will help to be sure of the original problem.
- Do not use flank infeed on work hardening materials.

  Problem Cause and Remedy
Pitch error (on CNC machines)
  • Starting too close to workpiece.
  • Saddle speed towards chuck is excessive.
  • Start cycle further back from workpiece.
  • Reduce speed by 10% until correct.
  • Change insert earlier.
Thread torn on one side only
  • Incorrect helix angle in toolholder.
  • Check helix chart.
  • Reassemble with correct anvil.
  • Check centre height.
Thread torn on both sides
  • Running too slow.
  • Built up edge.
  • Increase surface speed.
  • Check centre height.
  • Use coated grade.
  • Compare thread speed with turning speed.
Long dangerous swarf
  • Incorrect chipbreaker geometry.
  • Incorrect method of infeed.
  • Use Canela (TD) chipbreaker.
  • Use different infeed method.
Vibration chatter marks on both flanks
  • Poor stability.
  • Excessive overhang.
  • Renew anvil to support insert.
  • Check tool clamping.
  • Reduce tool overhang.
  • Check rigidity of setup.
Shallow threads
Problem with gauging
  • Insert not cresting.
  • Incorrect effective diameter.
  • Check machined diameters.
  • Excessive tool wear or chipped on nose see remedies above.