Inspecting everything is expensive. Inspecting nothing is more expensive. Deciding where to place quality control checkpoints is therefore an economic judgement, and it is one most small manufacturers make by accident — usually by inspecting at the end, where defects cost the most to correct.

The Cost of a Defect Rises with Every Step

A fault caught at the workstation costs minutes. The same fault caught at final inspection costs the value of everything added since. Caught by the customer, it costs the rework, the freight, the credit note and a portion of the relationship. Checkpoint placement is about intercepting error as early as its cost begins to climb.

Four Positions that Usually Earn Their Keep

Define the Criterion, Not the Inspection

"Check the part" is not a control. A control states what is measured, with what instrument, against which tolerance, how often, and what happens when it fails. Without the failure path, the operator's only options are to stop the line or to pass the part, and under time pressure the second usually wins.

Prefer Verification by the Person Doing the Work

Checks performed by the operator at the point of work are faster, cheaper and better understood than checks performed later by someone else. Reserve independent inspection for the small number of characteristics where the consequence of escape is severe.

Record Only What You Will Use

Every check generates a record and every record costs time. Capture the data you will actually analyse — defect type, stage, frequency — and drop the rest. A simple weekly tally of defects by category and stage, reviewed by the owner, drives more improvement than a filing cabinet of unread sheets.

A well-placed control system does not slow production. It shortens it, because less work has to be done twice.