Sandvik Coromant Threading - Manual (Page 20)

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2. Applications – Thread turning
Infeed depths per pass
Decreasing depth per pass (constant chip area)
• First choice, most common
• First pass is deepest
• More ‘balanced’ chip area
• Even load on insert
• Last pass 0.07 mm (.003 inch)
Constant depth per pass
• Each pass is of equal depth, regardless of number of passes
• More demanding on the insert
• Can improve chip control
• Increases the required number of passes
• Should not be used for pitches larger than 1.5 mm or 16 t.p.i.
• A less-productive method
First choice
Normal CNC lathes are equipped with dedicated threading cycles,
where pitch, thread depth and number of passes can be set in dif-
ferent ways – including the fi rst and last passes.
For the last pass, we strongly recommend against using a spring
pass (a cut without radial cutting depth). It is more benefi cial to use
the recommended infeed cycles to ensure better thread quality and
longer insert tool life.