CNC Machine 5

Question 1

What is the primary advantage of a direct-drive spindle motor compared to a belt-driven spindle?

Accepted Answer

Elimination of belt wear, vibration, and power loss between motor and spindle

Answer

Direct-drive spindles couple the motor shaft directly to the spindle, eliminating belt slippage, vibration, and transmission losses for improved accuracy and surface finish.

Question 2

A CNC machine's control panel shows an 'E-stop' (emergency stop) fault. What must an operator do before resuming machining?

Accepted Answer

Identify and resolve the cause, reset the E-stop, then re-home the machine axes

Answer

After an E-stop, the cause must be found and corrected, the E-stop button released, and axes re-homed because position data may have been lost during the fault.

Question 3

What is the function of 'G-code canned cycles' (such as G81 or G83) on a CNC machine?

Accepted Answer

To execute repetitive multi-step operations like drilling with a single block of code

Answer

Canned cycles condense complex, repetitive operations like drilling, tapping, or boring into a single G-code block, simplifying programs and reducing errors.

Question 4

Which machine characteristic defines how quickly an axis can reverse direction and reach programmed velocity, affecting corner accuracy?

Accepted Answer

Servo loop gain and acceleration rate

Answer

The servo loop gain and maximum axis acceleration determine how fast the machine can reverse and track programmed velocity, directly impacting corner geometry accuracy.

Question 5

On a CNC lathe, what is the purpose of the steady rest?

Accepted Answer

To support long, slender workpieces and prevent deflection during turning

Answer

A steady rest provides an intermediate support point along a long workpiece, preventing it from deflecting or vibrating under cutting forces.

CNC - Cutting Practice Test

CNC - Cutting Practice Test

CNC Machine 5