tailieunhanh - Dimensioning and Tolerancing Part 3

Tham khảo tài liệu 'dimensioning and tolerancing part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ASME DIMENSIONING AND TOLERANCING plicable to control angularity perpendicularity or pariỉỉeỉism of the feature. See para. . b Specify a zero positional tolerance at MMC including a datum reference at MMC if applicable to control coaxial or symmetrical features. See paras. and . c Indicate this control for the features involved by a note such as PERFECT ORIENTATION or COAXIALITY or LOCATION OF SYMMETRICAL FEATURES AT MMC REQUIRED FOR RELATED FEATURES. d Relate dimensions to a datum reference frame by a local or general note indicating datum precedence. See para. . The noted dimensions define only the maximum material condition envelope related to the datum reference frame defined by the datums. For LMC see para. c . APPLICABILITY OF RFS MMC AND LMC Applicability of RFS MMC and LMC is limited to features subject to variations in size. They may be datum features or other features whose axes or center planes are conữolled by geometric tolerances. In the case of straightness covered in paras. and it is the derived median line and the derived median plane rather than the axis and center plane that are controlled. In all cases the following practices apply for indicating RFS MMC and LMC fl All Applicable Geometric Tolerances Rule 2 . RFS applies with respect to the individual tolerance datum reference or both where no modifying symbol is specified. MMC or LMC must be specified on the drawing where it is required. NOTE Circular runout total runout concentricity and symmetry are applicable only on an RFS basis and cannot be modified to MMC or LMC. b Alternative Practice. For a tolerance of position Rule 2a RFS may be specified on the drawing with respect to the individual tolerance datum reference or both as applicable. See Appendix D Fig. D-l . Effect of RFS. Where a geometric tolerance is applied on an RFS basis the specified tolerance is independent of die actual size of the considered feature. .