Dimensional inspection begins with an agreed reference. If a drawing shows nominal dimensions without identifying important tolerances, inspectors and suppliers may reach different conclusions about acceptability. Resolve fit-critical dimensions and measurement methods before manufacturing starts.
Identify what controls fit
Mark dimensions that connect to site openings, adjacent parts or fixing locations. Ask the designer or responsible specialist to establish acceptable limits for those features. Avoid applying one tolerance to every dimension simply because it is convenient for the inspection sheet.
Make measurement repeatable
Specify the reference edges or datums, the item condition during measurement and the appropriate instrument. For an assembly, distinguish overall dimensions from component dimensions. Record whether a part is measured before or after coating, assembly or adjustment where that changes the result.
Inspection record
- Part number and drawing revision.
- Dimension being checked and its acceptance limits.
- Actual reading with a clear photograph where useful.
- Instrument identification and any measurement limitations.
When a discrepancy appears, determine whether it affects function, installation or appearance before agreeing a remedy. Do not alter the drawing merely to make an out-of-specification item pass. Any accepted deviation should be recorded by the authorized project decision-maker and linked to the affected parts.
AN Sourcing buying notes. These are practical procurement checklists; specifications, service scope and destination requirements should be confirmed for the actual order.