Safety Standards & Maintenance Practices 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 Safety Standards & Maintenance Practices flashcards as text
What does the machine tool builder's recommended 'warm-up cycle' accomplish on a CNC machining center?
Answer: Thermally stabilizes the spindle and axes to minimize thermal growth errors
Warm-up cycles gradually bring spindle bearings and axis components to operating temperature, reducing thermal expansion errors during precision machining.
According to OSHA standards, a CNC machine's interlocked enclosure guard must:
Answer: Stop all hazardous motion when the guard is opened during automatic operation
OSHA and ANSI B11 standards require that interlocked guards interrupt all hazardous motion—not just coolant—whenever the enclosure is opened during automatic cycle.
A CNC mill's spindle draws significantly higher current than normal during light finishing cuts. This most likely indicates:
Answer: Worn or contaminated spindle bearings causing excessive friction
Elevated spindle current during light cuts signals increased mechanical resistance, most commonly from degraded or contaminated bearings requiring inspection.
Before replacing a CNC servo amplifier or drive board, the technician must first:
Answer: De-energize the machine and discharge DC bus capacitors per the manufacturer's procedure
DC bus capacitors in servo drives can hold lethal voltages long after power-off; manufacturer discharge procedures must be followed before any drive board work.
What is the purpose of checking backlash during CNC machine preventive maintenance?
Answer: To measure lost motion between the servo drive and the axis leadscrew or ball nut
Backlash measurement quantifies the mechanical play in the drive train; excessive backlash causes positioning errors and must be compensated or corrected.
Which PPE is specifically required when handling solid carbide CNC cutting tools?
Answer: Cut-resistant gloves and safety glasses
Carbide tool edges are extremely sharp and brittle; cut-resistant gloves protect hands from laceration, and safety glasses protect eyes from edge chipping.
A CNC operator notices the X-axis position display drifts by 0.005" over 30 minutes with no commanded movement. This is most likely caused by:
Answer: Encoder feedback drift or a faulty servo drive holding register
Uncommanded axis drift with no motion command is a control or feedback problem, typically a failing encoder or servo drive losing its position register.