Analyze cylindrical inspection measurements across multiple sections, calculate dimensional variation along the feature, and compare the estimated cylindricity variation with a specified limit.
| Section | Minimum | Maximum | Section Variation |
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Cylindricity is a form characteristic that controls how closely a cylindrical surface conforms to an ideal cylinder. It considers the overall cylindrical form rather than only one circular cross-section.
For shafts, bores, sleeves and turned cylindrical components, inspection measurements taken at multiple sections can reveal changes in diameter and cylindrical form along the feature length.
This tool uses four inspection sections. Each section contains a minimum and maximum measured diameter. The calculator finds the lowest measurement and highest measurement across all sections.
The result is compared with the entered cylindricity limit. This provides a simplified screening calculation rather than a complete GD&T cylindricity evaluation.
A cylindrical component can vary along its length. Measuring only one cross-section may miss taper, barrel shape, necking or other dimensional changes.
Shafts and bearing journals often require controlled cylindrical form because variation can affect bearing contact, rotation, sealing and component fit.
Internal cylindrical features can also require controlled form. Bores, tubes and sleeves may need consistent geometry for bearings, seals, bushings or mating components.
Roundness controls the form of an individual circular cross-section. Cylindricity controls the complete cylindrical surface and therefore considers form along the length as well as around the circumference.
A shaft can have good roundness at one measured section while still having significant variation along its length.
Straightness and cylindricity are different geometric characteristics. Straightness can control a line element or axis, while cylindricity controls the entire cylindrical surface.
A cylindrical feature may therefore require separate consideration of its form and its axis or location depending on the engineering drawing.
Runout is evaluated relative to a datum axis while a component rotates. Cylindricity is a form control and does not require a datum for its basic definition.
Runout measurements can be affected by both form and axis-related conditions, whereas cylindricity focuses on the cylindrical form itself.
Each inspection section has its own local variation, calculated from the maximum and minimum diameter measured at that section.
Comparing section variations helps identify whether the largest local dimensional change occurs at a particular location.
Tolerance utilization shows how much of the specified cylindricity limit is consumed by the calculated overall variation.
For example, an overall variation of 0.06 mm against a 0.10 mm numerical limit represents 60% utilization.
Remaining tolerance is the difference between the specified limit and the calculated overall variation.
A positive value indicates that the simplified measured variation remains inside the entered limit. A negative value means the limit has been exceeded.
This calculator provides a simplified inspection analysis based on minimum and maximum diameter measurements from four sections. It is not a complete cylindricity measurement algorithm.
Formal cylindricity evaluation can involve a defined tolerance zone, measurement strategy, sampling density, filtering and appropriate reference geometry. The correct method depends on the engineering drawing and applicable inspection standard.
What does this cylindricity calculator measure? It calculates a simplified overall diameter variation from the lowest and highest measurements across four inspection sections.
Why use four sections? Multiple sections help reveal dimensional changes along the length that a single cross-section could miss.
What is section variation? It is the maximum measured diameter minus the minimum measured diameter within one inspection section.
Is cylindricity the same as roundness? No. Roundness applies to an individual cross-section, while cylindricity controls the overall cylindrical form.
Can this tool be used for bores? Yes. It can analyze entered internal diameter measurements from multiple bore sections.
What does 100% utilization mean? The calculated overall variation is exactly equal to the specified numerical limit.
Does PASS certify the component? No. It only means the simplified calculated variation is within the entered limit.