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Dimensioning and Tolerancing Part 14

Tham khảo tài liệu 'dimensioning and tolerancing part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ASME Y14.5M-1994 DIMENSIONING AND TOLERANCING forces are those that would be exerted in the assembly or functioning of the part. However if the dimensions and tolerances are met in the free state it is usually not necessary to restrain the part unless the effect of subsequent restraining forces on the concerned features could cause other features of the part to exceed specified limits. Free state variation of nonrigid parts may be controlled as described in the following paragraphs. 6.8.1 Specifying Geometric Tolerances on Features Subject to Free State Variation. Where an individual form or location tolerance is applied to a feature in the free state specify the maximum allowable free state variation with an appropriate feature control frame. See Fig. 6-53. The free state symbol may be placed within the feature conữol frame following the tolerance and any modifiers to clarify a free state requirement on a drawing containing restrained feature notes or to separate a free state requirement from associated features having restrained requirements. See Figs. 3-18 and 6-54. 6.8.2 Specifying Geometric Tolerances on Features to Be Restrained. Where orientation runout or location tolerances are to be verified with the part in a resưained condition select and identify the features pilot diameter bosses flanges etc. to be used as datum surfaces. Since these surfaces may be subject to free state variation it is necessary to specify the maximum force necessary to restrain each of them. Determine the amount of the restraining or holding forces and other requirements necessary to simulate expected assembly conditions specify on the drawing that if restrained to this condition the remainder of the part or certain features thereof shall be within stated tolerances. See Fig. 6-54. 6.8.3 Average Diameter. Where form control such as circularity is specified in a free state for a circular or cylindrical feature the pertinent diameter is qualified with the abbreviation AVG. See Fig. .