Explanation of New Specifications Used in Geometric Dimensioning Model

Abstract

This article is based on rules used in ISO GPS standards. During few last years are applied to drawing documentation environment various modifiers, specifications, and symbols from 3D annotated model. There CAD model describes nominal shape of the part. Specifications are then defined by annotations directly in the 3D model [1, 2]. Specifications from 3D annotations are applied in 2D drawing documentation now. The significance of these specifications (modifiers) from field of geometric tolerance is same in 2D and in 3D documentation. This is the reason why it is necessary to know, recognize and applied these specifications. The basis for these specifications is the latest edition of the standard ISO 1101 from 2017. Main new specifications are: intersection plane indicator; orientation plane indicator; direction feature indicator; collection plane indicator. With these specifications, disappeared dependence of placement of geometric tolerances on specific 2D view in orthographic projection (ISO E). The method of evaluation for metrology was also better specified. Used these specifications, we can better and more clearly positioned geometric tolerances on a 2D drawing or also into a parametric 3D CAD model using PMI dimensions. This article explains application of these new symbols to specific components with detailed descriptions. Apart from symbols for geometrical tolerances, are also very important symbols for datum, which are defined in ISO 5459. Furthermore, the issue of linear and angular dimensions from standards ISO 14405-1 and ISO 14405-3.