CFS Fastener Testing & Quality Control 3

Question 1

What does the term 'lot traceability' mean in fastener quality control?

Accepted Answer

Tracking a fastener from raw material heat through finished product

Answer

Lot traceability links each finished fastener lot back to the raw material heat, manufacturing records, and test data for accountability.

Question 2

A torque-tension test on a fastener assembly shows high clamp load variation. Which variable is most likely responsible?

Accepted Answer

Coefficient of friction between mating surfaces

Answer

Friction at the bearing face and in the threads accounts for approximately 90% of applied torque, so friction variation causes significant clamp load scatter.

Question 3

Which destructive test is specifically designed to detect seams, laps, or folds in the head of a bolt?

Accepted Answer

Macro etch examination

Answer

Macro etch (or cross-section examination) reveals internal discontinuities such as seams and cold-working defects in bolt heads.

Question 4

What is the significance of the 'acceptance quality limit' (AQL) in fastener inspection?

Accepted Answer

Percentage of defectives considered acceptable for a lot to pass

Answer

AQL defines the maximum percent defective (or defects per hundred units) that is still considered acceptable for routine sampling inspection.

Question 5

A hydrogen embrittlement susceptibility test requires fasteners to be loaded at what percentage of their proof load?

Accepted Answer

75%

Answer

Per ASTM F1940 and similar standards, sustained load tests for hydrogen embrittlement detection are typically conducted at 75% of proof load.

(CFS) Certified Fastener Specialist Practice Test

(CFS) Certified Fastener Specialist Practice Test

CFS Fastener Testing & Quality Control 3