Oblique cutting generates transverse cutting force which reduces tool life. Oblique cutting involves principal and auxiliary cutting edges in the cutting action which increases friction and advances wear in the cutting tool.

Orthogonal cutting doesn't have those complexities, but oblique cutting is found to be used in more often in an industrial setting.

Why are oblique cuts made instead of orthogonal cuts when it is more efficient to make an orthogonal cut?

Orthogonal and oblique cutting

  • $\begingroup$ Can you give some specific examples of where oblique cutting is used? The type of cut, shape of workpiece, and design intent will probably all factor in to the machining process. $\endgroup$ Apr 22 '15 at 15:37
  • 1
    $\begingroup$ It is used in turning of shafts. $\endgroup$ Apr 24 '15 at 7:22

Short answer

Orthogonal cutting increases pressure and decreases tool life. Thus isn't used if aim isn't cutting. Lathe operation is a shaping operation, not a cutting operation most of the time.

Long answer

Orthogonal cutting isn't suitable because

  1. Cutting forces act on a smaller area of cutting surface on tool if orthogonal cutting is employed so it increases wear on tool tip. However oblique cutting distribute cutting forces to greater area thus increases tool life.
  2. You usually don't want corners on your part. Corners reduce strenght and you want chamfers.
  3. Chip flow is another problem in orthogonal cutting.
  4. It's not possible to obtain perfect tool tip for orthogonal cutting, so addition of ploughing force increases total cutting force.

However, if you're trying to cut off a part you'll use orthogonal cutting. Below are some examples of cutting tool shapes Cutting tool shapes

Check Fundamentals of Metal Cutting and Machine Tools pages 117-139 which are accessible in Google Books.


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