CNC Quality Control and Inspection 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 Quality Control and Inspection flashcards as text
What does 'total runout' (as opposed to circular runout) control in GD&T?
Answer: All surface variations (radial and axial) along the entire length of a cylindrical feature
Total runout controls all surface variations — both radial and axial — over the entire length of a cylindrical or planar surface as it rotates about a datum axis.
In CMM measurement, what is the purpose of 'probe qualification'?
Answer: To determine the exact tip radius and position of the probe stylus for accurate measurement compensation
Probe qualification (or calibration) measures the actual stylus tip radius and its precise position so the CMM software can compensate for it in all measurements.
What does a negative Cpk value indicate about a manufacturing process?
Answer: The process mean is outside one of the specification limits
A negative Cpk means the process average has moved beyond one of the specification limits, indicating that a significant portion of parts are being produced out of tolerance.
In surface roughness measurement, what is the difference between Ra and Rz?
Answer: Ra is an arithmetic average while Rz is the average of the five largest peak-to-valley heights
Ra is the arithmetic mean roughness of the entire profile, while Rz averages the five highest peak-to-valley measurements within the evaluation length.
What is the purpose of 'first article inspection' (FAI) in CNC manufacturing?
Answer: To fully verify that the first production part meets all drawing requirements before running the batch
First article inspection fully documents and verifies that the first production part meets every dimension, tolerance, and requirement on the engineering drawing.
What does an out-of-round condition (ovality) in a CNC turned bore indicate about the machining process?
Answer: Possible chuck jaw distortion, worn spindle bearings, or workpiece deflection during turning
Ovality in a bore suggests the workpiece was distorted by clamping forces (from chuck jaws), or there is bearing wear or deflection causing non-circular tool paths.