Engineering guide
CNC machining tolerance planning for functional parts.
Tighter is not automatically better. Apply tolerance where function requires it, connect it to a clear datum strategy and make sure the requirement can be measured reliably.
Send drawings for reviewStart with
Assembly and functional requirements
Define
Datums, fits and critical characteristics
Avoid
Tight general tolerances without purpose
Confirm
Measurement method and report scope
Drawing strategy
Separate critical features from general geometry
When every dimension is treated as critical, cost rises and the true risks become harder to control. Use general tolerances for non-critical geometry and explicit callouts for function.
- Identify interfaces that control assembly
- Use datums that reflect functional setup
- Apply fits to mating diameter pairs
- Define surface finish only where needed
Measurement
A tolerance is incomplete without an inspection approach
Feature size, access, surface condition, temperature and datum simulation influence measurement. Discuss difficult characteristics before finalizing the quotation.
- Select tools appropriate to tolerance and geometry
- Clarify CMM datum alignment
- Define inspection frequency or sample size
- Agree report units, format and rounding
Questions buyers ask
Technical answers before the RFQ.
What standard CNC tolerance can MINGYU hold?
There is no single meaningful number for every feature. Capability is reviewed against geometry, size, material, process, setup and inspection method.
Should all drawing dimensions appear on a report?
Only if full dimensional reporting is required. Otherwise identify the critical characteristics and sampling expectations.
Continue your evaluation
Related manufacturing information
Capability is confirmed against your drawing.
Send CAD, drawing, material, quantity, finish, inspection requirements and target date for an engineer-led review.