Machine Design #99: Position Tolerance for Hole Patterns — Control Replaceable Assembly, Not Each Coordinate
MINATA turns the Vietnamese source into an evidence-led guide. hole-pattern position tolerance must preserve function, manufacturability, inspectability, cost, and serviceability when the boundary changes.
Function before a number
Write the input, expected result, acceptance limit, failure symptom, and measurement method before choosing a thickness, tolerance, datum, or hole pattern. Assign an owner to every value and change.
Core checks
- Assembly function and hole-pattern requirement: record value, source, method, owner, and pass/fail evidence.
- Datum order and mobility: record value, source, method, owner, and pass/fail evidence.
- Position tolerance, MMC, and virtual condition: record value, source, method, owner, and pass/fail evidence.
- Drill, reamer, CMM, or gauge method: record value, source, method, owner, and pass/fail evidence.
- Fastener clearance and replacement part: record value, source, method, owner, and pass/fail evidence.
- Capability, acceptance, and change control: record value, source, method, owner, and pass/fail evidence.
| Failure mode | Symptom | Verification |
|---|
| Function not defined | Over-tight or weak design | Rebuild the functional stack |
| Datum not real | Inspection and assembly disagree | Try the real fixture |
| Documents out of sync | Correct number, wrong revision | Baseline every reference |
1. Review pass: function and load path
Review function and load path for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
2. Review pass: datums and interfaces
Review datums and interfaces for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
3. Review pass: process capability
Review process capability for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
4. Review pass: assembly and maintenance
Review assembly and maintenance for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
5. Review pass: inspection and uncertainty
Review inspection and uncertainty for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
6. Review pass: failure and recovery
Review failure and recovery for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
7. Review pass: supplier and acceptance
Review supplier and acceptance for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
8. Review pass: revision and change
Review revision and change for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
9. Review pass: cost and trade-off
Review cost and trade-off for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
10. Review pass: safety and misuse
Review safety and misuse for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
11. Review pass: data and audit
Review data and audit for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
12. Review pass: training
Review training for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
13. Review pass: field feedback
Review field feedback for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
14. Review pass: release evidence
Review release evidence for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
15. Review pass: function and load path
Review function and load path for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
16. Review pass: datums and interfaces
Review datums and interfaces for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
17. Review pass: process capability
Review process capability for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
18. Review pass: assembly and maintenance
Review assembly and maintenance for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
19. Review pass: inspection and uncertainty
Review inspection and uncertainty for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
20. Review pass: failure and recovery
Review failure and recovery for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
21. Review pass: supplier and acceptance
Review supplier and acceptance for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
22. Review pass: revision and change
Review revision and change for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
23. Review pass: cost and trade-off
Review cost and trade-off for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
24. Review pass: safety and misuse
Review safety and misuse for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
25. Review pass: data and audit
Review data and audit for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
26. Review pass: training
Review training for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
27. Review pass: field feedback
Review field feedback for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
28. Review pass: release evidence
Review release evidence for the hole-pattern position tolerance. The key risk is functional pattern, virtual condition, datum mobility, assembly, and inspection. Define lower and upper boundaries, the simultaneous worst case, evidence source, owner, and change trigger. Confirm model, drawing, BOM, material, process, inspection, and work instruction use the same revision. Test normal assembly, variation, wrong input, interruption, and a controlled fault. Record actual value, unit, condition, instrument or log, sample or serial, pass/fail, and next action.
MINATA release checklist
- [ ] Function, boundary, and failure symptom are written.
- [ ] Datums, ownership, process, and mistake-proofing are clear.
- [ ] Six topic checks have evidence and pass/fail limits.
- [ ] Manufacturing, assembly, inspection, and maintenance were tried.
- [ ] Revision, supplier, material, and configuration records agree.
Good engineering is an explicit chain that survives manufacture, operation, maintenance, and change. For hole-pattern position tolerance, evidence that function and variation remain reliable is the MINATA standard.
Public references
- MINATA Q-up design practice and internal review checklist.
- Applicable drawing, material, molding, or quality standard selected by the project owner.
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