Compare measured metal surface deviation with a specified flatness tolerance and calculate pass/fail, remaining tolerance and tolerance utilization.
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Flatness describes how closely a metal surface conforms to a required planar condition. Sheet, plate, strip and other metal products can have surface deviations caused by rolling, forming, residual stress, thermal effects, handling or subsequent fabrication.
A flatness tolerance defines the maximum permitted deviation according to the applicable drawing, material specification, product standard or inspection requirement.
This calculator performs a straightforward maximum-deviation comparison between the measured value and the specified flatness limit.
If the measured deviation is greater than the specified limit, the numerical result is FAIL.
The remaining tolerance indicates how much of the specified flatness allowance is still available.
A positive value means tolerance remains. Zero means the measurement is exactly at the limit. A negative value means the limit has been exceeded.
Tolerance utilization shows what percentage of the specified flatness limit has been consumed by the measured deviation.
For example, a measured deviation of 2 mm against a 4 mm limit uses 50% of the available numerical tolerance.
Flatness requirements can vary substantially according to material grade, thickness, width, length, product class and governing standard.
There is therefore no single universal flatness limit that applies to every sheet or plate. The specified limit for the actual product should always be used.
Thickness tolerance and flatness tolerance describe different characteristics.
Thickness measures the material dimension through its section, while flatness describes deviation of a surface from the required planar condition. A product can satisfy one requirement and fail the other.
Flatness concerns a surface or planar condition. Straightness generally concerns a line element or feature.
They should not automatically be treated as interchangeable inspection requirements. The applicable drawing or specification defines the required geometric characteristic.
This calculator performs a numerical comparison only. It does not determine the correct flatness standard or prescribe how measurements must be taken.
Actual acceptance may depend on the applicable product specification, drawing, inspection plan, reference method, measurement locations and calibrated equipment.
When does the flatness check pass? The numerical check passes when the measured maximum deviation is less than or equal to the specified maximum flatness limit.
What is remaining tolerance? It is the specified flatness 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 this be used for steel plate? Yes, when the applicable flatness limit and measured deviation are already known.
Does PASS certify the material? No. It only confirms that the entered numbers satisfy the mathematical comparison.