The Term of RFS The Regardless of Feature Size(RFS)is when a geometric tolerance (or datum) applies independent of the feature size. That is,the geometric tolerance is limited to the stated amount regardless of the size of the feature-of-size. Shanghai Jiao Tong University 6
Shanghai Jiao Tong University 6 The Term of RFS n The Regardless of Feature Size (RFS) is when a geometric tolerance (or datum) applies independent of the feature size. That is, the geometric tolerance is limited to the stated amount regardless of the size of the feature-of-size
Rules for Tolerancing RULE-2:For tolerance of position,S,L,or M must be specified on the feature control frame,with respect to the tolerance value,datum reference,or both. 0.5D H E S,L.OR M MUST BE SPECIFIED IF THE DATUM IS A FEATURE-OF-SIZE Shanghai Jiao Tong University 7
Shanghai Jiao Tong University 7 Rules for Tolerancing
Rules for Tolerancing RULE-3:For other than tolerance of position,RFS applies with respect to the tolerance,datum reference,or both,if no modifier is specified. 0.12 (RFS applies) 0.6 (RFS applies) 0.1 M A (MMC is specified) Shanghai Jiao Tong University 8
Shanghai Jiao Tong University 8 Rules for Tolerancing
Exercise in Class If the block was at MMC,what would its straightness be limited to? the flatness of surface A be limited to? If the block was at LMC,the flatness of surface A would be limited to and the flatness of surface B would be limited to Could both of these flatness conditions exist simultaneously?Why? If the block was at LMC and the flatness of surface A was 0.3. what would the flatness of surface B would be limited to? SURFACE A- 12.2 16,2 118 16.0 SURFACE B Shanghai Jiao Tong University
Shanghai Jiao Tong University 9 Exercise in Class n If the block was at MMC, what would n its straightness be limited to? n the flatness of surface A be limited to? n If the block was at LMC, the flatness of surface A would be limited to and the flatness of surface B would be limited to . Could both of these flatness conditions exist simultaneously? Why? n If the block was at LMC and the flatness of surface A was 0.3, what would the flatness of surface B would be limited to?
Location Control Position and concentricity controls Controls locations of features such as holes,slots,bosses,etc.from datum features Controls center distances between such features Positional tolerances defines a zone within which the center,axis or center plane of a feature of size is allowed to vary from the theoretical (exact)position Shanghai Jiao Tong University 10
Shanghai Jiao Tong University 10 Location Control