Machine Flashcards
7 cards from real CNC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Machine flashcards as text
What is the primary advantage of a direct-drive spindle motor compared to a belt-driven spindle?
Answer: Elimination of belt wear, vibration, and power loss between motor and spindle
Direct-drive spindles couple the motor shaft directly to the spindle, eliminating belt slippage, vibration, and transmission losses for improved accuracy and surface finish.
A CNC machine's control panel shows an 'E-stop' (emergency stop) fault. What must an operator do before resuming machining?
Answer: Identify and resolve the cause, reset the E-stop, then re-home the machine axes
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.
What is the function of 'G-code canned cycles' (such as G81 or G83) on a CNC machine?
Answer: To execute repetitive multi-step operations like drilling with a single block of code
Canned cycles condense complex, repetitive operations like drilling, tapping, or boring into a single G-code block, simplifying programs and reducing errors.
Which machine characteristic defines how quickly an axis can reverse direction and reach programmed velocity, affecting corner accuracy?
Answer: Servo loop gain and acceleration rate
The servo loop gain and maximum axis acceleration determine how fast the machine can reverse and track programmed velocity, directly impacting corner geometry accuracy.
On a CNC lathe, what is the purpose of the steady rest?
Answer: To support long, slender workpieces and prevent deflection during turning
A steady rest provides an intermediate support point along a long workpiece, preventing it from deflecting or vibrating under cutting forces.
What does 'machine zero' (machine origin) represent in a CNC machine's coordinate system?
Answer: The fixed, absolute reference point established by the machine manufacturer
Machine zero is the fixed absolute reference point set by the machine manufacturer, from which all work offsets and tool offsets are ultimately derived.
Which safety device on a CNC machine physically prevents axis overtravel beyond the machine's mechanical limits?
Answer: Hard limit switches (over-travel switches)
Hard limit switches are physical sensors that trigger an immediate stop if an axis travels beyond its programmed soft limits, preventing mechanical damage.