Tolerance Analysis Report Template
A tolerance stack that lives only in an engineer's spreadsheet is hard to review and easy to forget. This template gives the study a standard structure so a reviewer can see the requirement, method, inputs, result and decision at a glance.
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Tolerance Analysis Report Template
Tolerance Analysis Report
Company: Acme Precision Ltd Report: TA-2026-019 Date: 2026-10-20 Assembly: ASSY-7720 Gearbox, DWG-77200 Rev D Analyst: R. Menon
1. Requirement
End float of the output shaft shall be between 0.05 mm and 0.30 mm over the operating temperature range.
2. Method and assumptions
Method: Worst case
All dimensions at 20 C. Parts conform to drawing. Thermal growth analysed separately in section 4.
3. Contributor list (loop)
| Item | Part and feature | Nominal | Tolerance | Direction (+/-) | Distribution |
|---|---|---|---|---|---|
| 1 | |||||
| 2 | |||||
| 3 | |||||
| 4 |
4. Results
Worst-case gap ranges from 0.02 mm to 0.34 mm. The upper bound meets the requirement; the lower bound does not.
5. Recommendation
Add a 0.05 mm shim grade selection at assembly, or tighten bearing housing depth tolerance from +/-0.05 to +/-0.03.
Review and approval
Run the actual numbers in your calculator or spreadsheet and paste the results here. The report documents the reasoning, it does not compute the stack.
Keep engineering analysis with your part records
Optional review of how reports could link to PLM and ERP items.
Optional. The tool and every export work without this. No spam.
How to use it
State the requirement as a measurable gap, fit or alignment limit, choose the analysis method and write down your assumptions. List every contributor in the loop table with its nominal, tolerance, direction and distribution, then summarize the result and recommendation. Export to Word or PDF and attach it to the design review or ECN.
Choosing the method
Worst case assumes every part is at its limit simultaneously, so it guarantees the requirement but can force tight, expensive tolerances. RSS assumes independent, roughly normal variation and gives a smaller expected spread, but allows a small fraction of assemblies to fall outside. Monte Carlo handles non-normal distributions and nonlinear loops.
- Safety-critical gap: worst case
- High volume, capable processes: RSS or statistical
- Complex or nonlinear loops: simulation
- Always state which one you used and why
Common mistakes
Common errors are missing contributors such as coating thickness, thermal growth or form error, mixing up the direction of a dimension in the loop, and using RSS on parts that come from a single tooling cavity or a single machine setup, which makes variation correlated. Document those assumptions explicitly so the next engineer can challenge them.
Frequently Asked Questions
When is worst case required?
When failure is safety-critical, parts are low volume, or process capability is not known. Otherwise a statistical method may be acceptable, if agreed with the customer or design authority.
What belongs in the loop?
Every dimension that adds to or subtracts from the gap along the path through the assembly, including bearings, shims, seals, fits and thermal effects. Missing a contributor is the most common cause of surprise.
Do I need a datum scheme for the analysis?
It helps. Geometric tolerances such as position and perpendicularity contribute to the loop, so know how each is referenced. The datum template in this set can record that.
Should the report be revision controlled?
Yes. If a drawing tolerance changes, the analysis may no longer be valid. Store it with the assembly and reference its revision.
If analysis results are filed outside your PLM and ERP, we can discuss linking them to the drawing and part records.
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