Machine Flashcards

What does 'spindle runout' measure on a CNC machine?

Answer: The deviation of the spindle centerline from true rotation

Spindle runout is the radial deviation of the rotating spindle from its true centerline, which directly affects surface finish and tool life.

In a CNC turning center, what is the purpose of the turret?

Answer: It holds multiple cutting tools and indexes them into position

The turret on a lathe holds multiple tools and rotates (indexes) to bring each tool into the cutting position without manual changes.

What machine feature allows a CNC mill to tilt its spindle or table to machine angled features without repositioning the part?

Answer: 4th or 5th axis (tilt axis)

A 4th or 5th rotary/tilt axis allows the machine to reorient the cutting tool relative to the part for complex angled surfaces in a single setup.

Why is machine thermal stability important in precision CNC machining?

Answer: Thermal expansion changes machine geometry, causing dimensional errors

As machine components heat up, they expand and shift, altering the relative positions of the spindle and workpiece, causing out-of-tolerance parts.

What is the role of a CNC machine's servo drive (amplifier)?

Answer: To convert low-power control signals into high-power motor commands

The servo drive receives position/velocity commands from the controller and amplifies them to supply the power needed to drive the servo motor accurately.

A CNC machine's axis position feedback is provided by an encoder. What type of encoder reads position relative to a fixed reference mark?

Answer: Absolute encoder

An absolute encoder stores the actual position value at every point, so the controller knows the exact location even after a power loss without homing.

Which machine component on a CNC lathe holds and rotates the raw workpiece during turning?

Answer: Chuck (spindle nose)

The chuck mounted on the spindle nose grips and rotates the workpiece, while the cutting tool removes material as the part spins.