ISO 2692-2021 pdf download.Geometrical product specifications (GPS]一. Geometrical tolerancing 一Maximum material requirement (MMR], least material requirement (LMR) and reciprocity requirement (RPR).
When an MMR or LMR applies to several toleranced features, the symbols CZ or SZ shall always be indicated in the zone section of the tolerance indicator following the sequence order specified in
Iso 1101.
NOTE See Annex B for former practice.
4.1.5 Simultaneous requirement
A simultaneous requirement can be useful for example for MMR or LMR with same datum indication containing MMR or LMR.
When a simultaneous requirement is needed, the SIM symbol possibly followed by an identification number (SIMI) without a space shall be indicated in the adjacent indication area of each related geometrical specification in accordance with ISO 5458.
The use of the SIM modifier transforms a set of more than one geometrical specification with MMR or LMR into a combined specification. The corresponding MMVC or LMVC are locked together with location and orientation constraints according to the rules of this document. The datum system is also constrained to be the same for each specification in the same SIM group.
Figure A.17 shows an example of simultaneous requirement.
4.1.6 MMR or LMR on a datum without MMR or LMR on the toleranced feature
When an MMR or LMR is applied to the datum only (see Figure A.19). then the rules for datum fully apply (see 4.2.2. 4.2A and 4.3.2. 4.3A). In addition, the constraints on the MMVC(s) of the datum(s) and the MMVC(s) of the toleranced feature(s) stated in rule D [see 42J. d)] or in rule K (see 4I1 d)] are replaced with the corresponding constraints applied on the MMVC(s) of the datum(s) and the tolerance zone as defined in ISO 1101 and ISO 5459.
4.2 Maximum material requirement (MMR)
4.2.1 MMR for toleranced features with indirect determination of virtual size
When the MMR applies to the toleranced feature and the indirect determination of virtual size is selected, it shall be indicated on drawings by the symbol @ placed after the geometrical tolerance of the derived feature of the feature of linear size (toleranced feature) in the tolerance indicator with no size indicated in square brackets.
The MMR for toleranced features with indirect determination of virtual size results in four independent requirements:
— a requirement for the upper limit of the size [see rules A 1) and A 2)j;
— a requirement for the lower limit of the size [see rules B 1) and B 2)1:
— a requirement for the surface non-violation of the MMVC (see rule C);
— a requirement for applying constraints on MMVCs (see rule 0).ISO 2692 pdf download.