Threading Insert Nomenclature for CNC Dummies

Today I am going to explain the threading insert nomenclature which are used for threading on cnc machines. Of course there are plenty of different types of threading inserts and the same way there are multiple threading insert nomenclatures. Here I am going to explain just one of the threading insert nomenclature. Although it looks a bit complex, but it is not that difficult to remember. Inserts nomenclature also helps when you are going to choose a new tool.

Threading Insert Nomenclature for CNC Dummies

Threading Insert Nomenclature for CNC Dummies

Threading Insert Nomenclature Explanation

Threading Insert Nomenclature for CNC Dummies

Threading Insert

  1. This tells style of the threading insert
    • R = Right hand style threading insert
    • L = Left hand style threading insert
  2.  Main Code for insert
  3. Type of machining
    • G = Insert for external threading
    • L = Insert for internal threading
  4. Insert dimensions. The threading insert dimension may be 11,16,22,27
  5. Thread profile
    • VM0  = V-profile 60°
    • MM0 = Metric 60°
    • UN0  = UN 60°
    • WH0 = Whitworth 55°
  6. Number of points per cutting edge
    • 1 = 1 point
    • 2 = 2 points
    • 3 = 3 points
  7. Cutting edge condition
    • – = Edge rounded
    • F = Sharp cutting edge
    • C = Chip breaking geometry
  8. Pitch
    • mm : pitch x 100
    • inch : number of threads per inch x 10
  9. Supplementary code

Everything is just self-explanatory.

The number 1 field for threading insert nomenclature tells whether the threading insert has a right hand style or a left hand style. This doesn’t mean that the right hand style threading insert can only be used for right hand thread cutting, we can machine left hand threads with right hand style threading insert, just direction of feed is to change. I will write about this in a future post.

When machining threads it must be insured that we are using the proper threading insert, you can’t use a threading insert which is made for internal threading for external thread machining. The field number 3 for the threading insert nomenclature tells this whether the threading insert is made for internal threading or for external threading.

Sometimes we have to make threads in very small bores so a bigger threading insert can’t be used there, so we will choose a threading insert which is smaller in size. The field number 4 tells about the size of the threading insert, the threading inserts sizes are 11, 16, 22 and 27.

Thread profile will be clear to everyone, there are multiple thread types and every thread type has its own angle and shape, and a threading insert which is made for 60° threads can’t make 55° threads. So it is must to use the proper profile threading insert. Threading insert nomenclature field number 5 tells this.

Some threading inserts has just one point per cutting edge, but some has two or three cutting point per cutting edge. The cutting edge points are increased to make fine threads and also help in making the proper thread profile.


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