CNC Maintenance and Troubleshooting Flashcards
6 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 6 CNC Maintenance and Troubleshooting flashcards as text
What is the primary purpose of ball screw lubrication in a CNC machine?
Answer: To reduce friction, prevent wear, and maintain positioning accuracy of the linear axes
Ball screw lubrication reduces friction between balls and raceways, prevents wear, dissipates heat, and maintains the tight positioning accuracy required for precision machining.
What condition is indicated by a 'following error' alarm on a CNC servo axis?
Answer: The actual axis position lags too far behind the commanded position
A following error occurs when the difference between the commanded position and the actual encoder-reported position exceeds the controller's tolerance, often caused by binding, overloading, or drive issues.
Why is it important to check and maintain the CNC machine's way lube system regularly?
Answer: To ensure the sliding guideways move freely and maintain their geometry over time
Way lube forms an oil film on the guideways (box ways or linear rails) that reduces friction, prevents stick-slip, and protects the precision surfaces from wear.
What does 'backlash' in a CNC axis mean?
Answer: The lost motion or play when a linear axis reverses direction
Backlash is the mechanical play (dead zone) in a drive system when the axis reverses direction — the motor turns but the axis does not move until the slack is taken up.
What is the purpose of an automatic tool length measurement (TLM) probe in a CNC machining center?
Answer: To automatically measure and store each tool's length offset after a tool change
A tool length measuring probe touches the tip of each tool and records its actual length in the offset table, eliminating manual tool-setting and ensuring accurate Z-axis positioning.
When a CNC machine produces parts that consistently measure on one side of the tolerance (all slightly oversize), what is the most likely cause?
Answer: A systematic offset error in the tool length, work coordinate, or tool radius compensation
A consistent directional size error indicates a systematic offset problem — the tool length offset, work zero, or cutter radius compensation contains an error that shifts all parts in the same direction.