How often should the die be backed off during external thread cutting?
Periodically during cutting to break chips, depending on material conditions
When an external thread is cut with a die, metal is removed as chips, and if these chips are not broken and cleared they pack into the die and tear the freshly formed thread.
To manage this, the operator does not simply drive the die straight on; the cutting action is interrupted deliberately.
The standard practice is to back off the die by turning it a part-turn in the reverse direction periodically as the cut advances, which snaps the chips and lets them fall clear before forward cutting resumes.
How frequently this reverse turn is needed depends on the material and cutting conditions, with tough or gummy metals needing more frequent backing off than free-cutting ones.
Backing off only once at the beginning would do nothing for the chips formed through the rest of the cut.
Backing off only at the end is far too late, and backing off only after each complete thread lets long chips build up over a full pitch and clog the die.
Hence, the answer is Periodically during cutting to break chips, depending on material conditions.
Similar Questions
When cutting an ISO Metric thread for a coarse pitch, by how many degrees should the compound rest be swiveled to?
Taps are re-sharpened by grinding:
The type of thread used in lead screw of a lathe is ______
The surface connecting crest and root of a thread is termed as
Angle of Knuckle thread is ______
Which one of the following is used to rectify damaged or rusted threads?
The resistance of fine thread unscrewing is ______
Lead is equal to double the pitch value then this type of thread is called as _____.
Identify the type of Die in the above Fig.
- The distance from a point on a thread to the corresponding point on the next thread of a screw is called ______.
Important Questions from Screw Threads
When cutting an ISO Metric thread for a coarse pitch, by how many degrees should the compound rest be swiveled to?
What is the blank size (diameter) for preparing a bolt of M12 × 1.5?
What is the relation between the lead (L) and pitch (P) of a two-start thread screw?
Taps are re-sharpened by grinding:
The form of thread in a saw tooth thread is
