SECTION 3 1 FORM TOLERANCES Form Tolerances Form

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SECTION 3. 1 FORM TOLERANCES

SECTION 3. 1 FORM TOLERANCES

Form Tolerances Form tolerances of a feature control only form deviations of the feature.

Form Tolerances Form tolerances of a feature control only form deviations of the feature. No datum is needed. There are 6 types of form tolerances. Toloerances Characteristics Straightness Flatness Form Roundness Cylindricity Profile any line Profile any surface Symbol

3. 1. 1 Straightness The straightness is very important parameter for the lethe bed

3. 1. 1 Straightness The straightness is very important parameter for the lethe bed rail.

3. 1. 1 Straightness A straightness tolerance can be used to control the straightness

3. 1. 1 Straightness A straightness tolerance can be used to control the straightness of surface elements or an axis. The tolerance specifies how close to perfectly straight a feature must be made.

3. 1. 1 Straightness(1) The tolerance zone is limited by two parallel straight lines

3. 1. 1 Straightness(1) The tolerance zone is limited by two parallel straight lines a distance t apart and in the specified direction only. Example of indication Any extracted line on the upper surface, parallel to the plane of projection shall be contained between two parallel straight lines 0. 05 mm apart. 0. 05

3. 1. 1 Straightness(2) The tolerance zone is limited by two parallel planes a

3. 1. 1 Straightness(2) The tolerance zone is limited by two parallel planes a distance t apart. Example of indication Any extracted (actual) generating line on the cylindrical surface shall be contained between two parallel planes 0. 05 mm apart. 0. 05

3. 1. 1 Straightness(3) The tolerance zone is limited by a cylinder of diameter

3. 1. 1 Straightness(3) The tolerance zone is limited by a cylinder of diameter t, if the tolerance value is preceded by the symbol ɸ. Example of indication The extracted median line of the cylinder to which the tolerance applies shall be contained within a cylindrical zone of diameter 0. 05 mm. Φ 0. 05

3. 1. 2 Flatness is a very important parameter for machine tool working surfaces.

3. 1. 2 Flatness is a very important parameter for machine tool working surfaces.

3. 1. 2 Flatness tolerances are only used to specify a form control for

3. 1. 2 Flatness tolerances are only used to specify a form control for flat surfaces.

3. 1. 2 Flatness The tolerance zone is limited by two parallel planes a

3. 1. 2 Flatness The tolerance zone is limited by two parallel planes a distance t apart. Example of indication The extracted (actual) surface shall be contained between two parallel planes 0. 05 mm apart. 0. 05

3. 1. 3 Roundness Bearing bore for roundness and cylindrical precision of the request

3. 1. 3 Roundness Bearing bore for roundness and cylindrical precision of the request is very high.

3. 1. 3 Roundness tolerances control the roundness of any feature that has a

3. 1. 3 Roundness tolerances control the roundness of any feature that has a circular cross section, including cylinders and cones. Although a cone does not have a constant diameter, it does have a circular cross section. Circularity tolerances are often referred to as roundness tolerances. cylinder cone

3. 1. 3 Roundness(1) The tolerance zone, in the considered cross-section, is limited by

3. 1. 3 Roundness(1) The tolerance zone, in the considered cross-section, is limited by two concentric circles with a difference in radii of t. Example of indication For the cylindrical surface, the extracted circumferential line, in any cross-section of the cylindrical, shall be contained between two coplanar concentric circles, with a difference in radii of 0. 05 mm. 0. 05

3. 1. 3 Roundness(2) The tolerance zone, in the considered cross-section, is limited by

3. 1. 3 Roundness(2) The tolerance zone, in the considered cross-section, is limited by two concentric circles with a difference in radii of t. Example of indication Any extracted circumferential line, resulting in the intersection of the (actual) revolute surface and a section cone shall be contained in a conical zone limited by two circles 0. 05 apart (this distance is taken on the generatrix). 0. 05

3. 1. 4 Cylindricity The form of a cylindrical surface can be controlled by

3. 1. 4 Cylindricity The form of a cylindrical surface can be controlled by a cylindricity tolerance. It can be applied to a shaft or hole. This tolerance type is, in effect, a combination of circularity and straightness tolerances. It also controls parallelism of the sides of the cylinder to prevent the part from being tapered. cylinder

3. 1. 4 Cylindricity The tolerance zone is limited by two coaxial cylinders with

3. 1. 4 Cylindricity The tolerance zone is limited by two coaxial cylinders with a difference in radii of t. Example of indication The extracted (actual) cylindrical surface shall be contained between two coaxial cylinders with a difference in radii of 0. 05 mm. 0. 05