SEP Separate requirement
Separate requirement · Modificadores de zona · ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Note: SEP REQT on two position frames on the same pattern” states a separate requirement requirement.
What controls
A note that explicitly overrides the simultaneous requirement: even if two feature control frames cite the same datums in the same order, each one is evaluated on its own, establishing the datum reference frame afresh for each group. The zones of one group are no longer locked relative to those of the other and each pattern can shift independently, which makes the criterion more permissive. It is used when the groups do not work together in the assembly: two patterns that receive two different components and do not need to maintain a relationship to each other. What it does NOT mean is that the datums change, or that each group can be measured in a different setup or datum order: the reference frame is the same, the only thing that happens is that each group is re-seated in it.
How to verify
The same setup and the same datum reference frame are kept, but in the software each feature control frame is declared as an independent requirement and each group is allowed to fit on its own within that frame. The report must make clear which groups were evaluated separately; if it does not say, anyone reviewing it later will assume the simultaneous criterion. A single functional gauge with all the pins is no good here, because it imposes the relationship between groups: you need separate gauges, one per group.
Common mistakes when interpreting it
- Assuming the separate requirement when the drawing does not state it: without a note, in ASME the simultaneous requirement applies.
- Taking it as permission to change setup or datum order for each group: the datum reference frame is still the same.
- Verifying with a single functional gauge covering all the groups, imposing a relationship between them that the note has just released.
How to get it in the workshop / if it comes out of tolerance
The opposite of SIM REQT. If there are several feature control frames on a pattern with no note, ask the customer which applies. It directly affects the inspection worst case. For production it is good news (it lets one group shift without dragging the other along), but it must not be assumed: on an ASME drawing with no note, the simultaneous criterion applies, which is stricter. If the supplier assumes separate and the customer evaluates simultaneous, the lot is rejected at receiving inspection.
If one group fails, treat it as a local problem: tool, strategy and offset for that group, without looking at the rest. If both fail with the same bias, the cause is common (work offset, datums or workholding) and is fixed in one go. Before rejecting, verify that the evaluation really was done separately, because the simultaneous criterion applied by mistake rejects good parts. And if the drawing does not carry the note and the parts only pass when evaluated separately, do not take it as given: ask the customer for clarification in writing.
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