Tolerances worth a conversation before quoting
Name the dimension, the feature and how it is checked. A screening number starts the discussion; the drawing carries the requirement.
Elise de WitInspection lead · 5 min read
A dimensional tolerance states the permitted variation for a named dimension. The ±0.02 mm choice in Check my part is a screening request. It does not promise that every feature on a drawing can be made or inspected to that number.
Start with the feature
A hole’s position, a surface relationship or a fit can need more information than its size. State the feature, the reference it is measured from and the inspection requirement your engineer has specified. Keep that requirement with the drawing revision.
Read the published range in context
For the listed metals, the screen uses ±0.05 mm on 3-axis milling and ±0.02 mm on 5-axis milling and turning. POM-C uses wider ranges: ±0.10 mm on 3-axis and ±0.05 mm on 5-axis and turning. Shape, size, quantity, finish and requested documents are checked separately.
A 6082-T6 block at 120 × 80 × 30 mm, 25 parts and ±0.02 mm needs a tolerance review on 3-axis milling. It screens within on 5-axis milling. Turning is outside because that record screens round parts. Geometry and drawing review still required.
One measured example
SAMPLE-01, revision A, gives one illustrative overall length: 120.00 mm with ±0.10 mm allowed variation. A measured example of 120.03 mm is within that interval. It says nothing about another feature, the whole part or whether that tolerance suits a real design.
Keep a drawing standard separate
A declared ISO general-tolerance class is separate from a numeric feature requirement. The check does not convert a class into one fixed ± value. Tighter or feature-specific requirements need review with the drawing, including the manufacturing and inspection work they add.
Bring these questions
- Which named features need the tighter requirement?
- Which datums or related faces define them?
- What inspection method and report are requested?
- Does a separate drawing standard apply?
- Which requirements are still undecided?
If you do not know the tolerance, choose Not specified yet and list the question. The review can then ask for the missing requirement before anyone quotes.
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