Quality Control & Inspection Flashcards

A coordinate measuring machine (CMM) is used in QC to:

Answer: Measure physical part geometry and compare it to nominal drawing dimensions

A CMM uses a probe to capture physical part coordinates and compare them against nominal geometry and tolerances defined in the drawing.

An engineering change order (ECO) raises the revision of a drawing from Rev B to Rev C. QC requires that:

Answer: The change is documented in the revision block with a description, date, and approval signatures

Each revision must be recorded in the drawing's revision block with a clear description, effective date, and required approval signatures per ASME Y14.100.

Which term describes the condition where a manufactured feature is exactly at the boundary defined by its size and geometric tolerance simultaneously?

Answer: Virtual condition

Virtual condition is the worst-case boundary envelope of a feature, combining its MMC (or LMC) size with its geometric tolerance for mating-part clearance calculations.

A drawing is submitted for QC review and the tolerance on a linear dimension reads '2.500 ±0.005'. A checker should verify that this tolerance:

Answer: Is achievable with the specified manufacturing process and does not create a stack-up issue

QC must confirm that specified tolerances can be produced by the designated process and do not create downstream assembly interference through tolerance accumulation.

What does it mean when a feature control frame contains the symbol 'P' (projected tolerance zone)?

Answer: The tolerance zone extends beyond the part into the mating assembly space

A projected tolerance zone (P) extends the positional tolerance zone above the part surface into the space where a fastener or pin will protrude, controlling its angular deviation.

During drawing review, a QC technician notices that two dimensions on the same view together over-define (fully constrain) a feature that is already located by a third dimension. This is called:

Answer: Redundant dimensioning (over-dimensioning)

Redundant or over-dimensioning occurs when more dimensions than necessary are applied, creating conflicts if the part is manufactured to any one of them.

A quality audit of drawing files reveals that several released drawings lack a material specification in the title block. The correct corrective action is to:

Answer: Issue ECOs to add the material callout to each affected drawing before next production run

Missing material specifications must be formally added via engineering change orders to ensure the correct material is used and the change is traceable.