Preventive Maintenance Schedules 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 Preventive Maintenance Schedules flashcards as text
A CNC machine PM schedule includes 'verify spindle orientation (M19) accuracy.' Why is this check important?
Answer: Ensures the ATC can engage the tool holder drive key reliably during tool changes
Spindle orientation positions the drive key so the ATC can consistently engage tool holders; drift in this position causes tool change crashes.
During a PM inspection, the technician measures the CNC machine table for flatness using a precision level. The reading shows a 0.002" per foot deviation. What is the appropriate response?
Answer: Document the finding and compare to machine specification tolerance before deciding on corrective action
The measurement must be compared against the manufacturer's tolerance specification before taking corrective action, as acceptable deviation varies by machine.
What does 'backlash compensation' refer to in the context of CNC machine PM?
Answer: A control parameter that compensates for the small lost motion when a screw reverses direction
Backlash compensation is a CNC parameter that adds a small extra move to overcome the play in the drive system when the axis reverses direction.
A PM checklist item states 'inspect and clean the linear scale encoder strips.' What type of contamination is most harmful to these components?
Answer: Metal chips and cutting fluid on the scale surface
Chips and coolant on encoder scale strips cause reading errors and can physically damage the delicate glass or stainless scale, leading to axis faults.
When conducting a PM on a CNC turning center, why is it important to check the turret indexing repeatability?
Answer: Turret position accuracy directly affects the dimensional accuracy of turned parts
If the turret doesn't return to the exact same position each time, the cutting tool position changes, causing dimensional variation in machined parts.
A PM procedure for a CNC machine requires 'checking and adjusting the belt tension on the spindle drive.' What tool is used to measure belt tension?
Answer: A belt tension gauge (sonic tension meter or deflection gauge)
Belt tension gauges measure deflection force or use sonic frequency methods to accurately set tension within the manufacturer's specified range.
During a PM review of a CNC machine's maintenance history, a technician notices that spindle bearing temperatures have been trending upward over the past six monthly checks. What is the most appropriate action?
Answer: Schedule a spindle inspection and bearing replacement before temperature reaches the alarm threshold
A rising temperature trend indicates progressive bearing degradation; proactive replacement prevents unplanned downtime and spindle damage.