Compare measured metal straightness deviation with a specified maximum limit and calculate pass/fail, remaining tolerance and tolerance utilization.
| Item | Value | Meaning |
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Straightness describes how closely a line element, axis or applicable metal feature follows the required straight condition. Deviations can occur in bars, rods, shafts, tubes, pipes, strips and structural sections during rolling, drawing, forming, heat treatment, machining, handling or storage.
A straightness tolerance establishes the maximum permitted deviation according to the applicable drawing, material specification, product standard or inspection requirement.
This calculator performs a maximum-deviation comparison between the measured straightness value and the specified straightness limit.
If the measured deviation is greater than the specified limit, the numerical result is FAIL.
Remaining tolerance indicates how much of the specified straightness allowance is still available after the measured deviation is considered.
A positive value means numerical tolerance remains. Zero means the measurement is exactly at the limit. A negative value means the specified limit has been exceeded.
Tolerance utilization shows what percentage of the specified straightness limit has been consumed by the measured deviation.
For example, a measured deviation of 1 mm against a 2 mm limit uses 50% of the specified numerical allowance.
Straightness requirements for bars and shafts can depend on diameter, length, material condition, manufacturing route and the applicable product specification.
A generic straightness value should not be assumed to be the correct acceptance limit for every product. The actual specified limit should always be used.
Straightness and flatness are different geometric characteristics. Straightness generally concerns a line element or axis, whereas flatness concerns an entire surface or planar condition.
For example, a long round shaft can have a straightness requirement for its axis, while a metal plate can have a flatness requirement for its surface.
Straightness and runout are also different inspection characteristics. Runout can describe variation relative to a datum axis during rotation, while straightness evaluates the relevant line element or axis against a straight condition.
The applicable engineering drawing and inspection specification determine which characteristic is required.
This calculator performs a numerical comparison only. It does not determine the applicable straightness standard, inspection length, datum system or measurement procedure.
Actual acceptance can depend on the applicable drawing, product standard, inspection plan, measurement equipment and environmental conditions.
When does the straightness check pass? The numerical check passes when the measured maximum deviation is less than or equal to the specified maximum straightness limit.
What is remaining straightness tolerance? It is the specified straightness limit minus the measured deviation.
What does 100% tolerance utilization mean? It means the measured deviation is exactly equal to the specified maximum limit.
What happens above 100% utilization? The measured deviation exceeds the specified limit and the numerical result becomes FAIL.
Can I use this for steel bars? Yes, when the applicable straightness limit and measured deviation are already known.
Is straightness the same as flatness? No. Straightness generally concerns a line element or axis, while flatness concerns a surface.
Does PASS certify the material? No. It only confirms that the entered measurement satisfies the mathematical comparison.