CNC Lathe Turning Operations Flashcards

On a CNC lathe, the turret index command is typically issued by:

Answer: A T-word followed by the tool and offset number

The T-word (e.g., T0202) selects the turret station and applies the corresponding tool geometry and wear offset.

What does 'tool nose radius' (TNR) compensation prevent when turning a chamfer?

Answer: Dimensional error caused by the rounded insert tip

Without TNR compensation, the rounded insert tip causes the chamfer to be slightly off the programmed angle; G41/G42 corrects for this geometrically.

Which parameter primarily determines thread pitch in a G32 (threading) block?

Answer: F-word (feed per revolution)

In G32 threading, the F-word specifies the feed rate in inches or millimeters per revolution, which equals the thread pitch.

When measuring a turned diameter with a micrometer and finding it 0.005" oversize, the operator should:

Answer: Subtract 0.0025" from the X wear offset

Because X is a diameter value and wear offset adjustment is a radius correction, subtracting 0.0025" (half of 0.005") from the X wear offset reduces the diameter by 0.005".

What is the function of the 'spindle encoder' on a CNC lathe during threading?

Answer: Synchronizes the Z-axis feed with spindle rotation

The spindle encoder provides a reference signal so the controller can synchronize Z-axis motion exactly with spindle rotation, ensuring accurate thread pitch.

Which facing strategy minimizes face runout on a thin disc turned between centers?

Answer: Light finishing pass from OD toward center at low feed

A light finishing pass from OD inward at low feed rate minimizes deflection and vibration on thin discs, yielding the flattest and most accurate face.

In a CNC lathe program, M08 and M09 control:

Answer: Coolant on and off

M08 activates flood coolant and M09 turns all coolant off; these are standard miscellaneous functions for coolant control.