This table identifies primary datum features regardless of material boundary. The degrees of freedom approach in establishing a datum-reference frame is not new, it was first introduced in the ASME Y14.5.1-1994 standard and is now a staple of the new ASME Y14.5-2009 standard.Ī degrees-of-freedom table has been added to the datum section. These degrees of freedom must be constrained to mathematically apply or measure geometric tolerances. The degrees-of-freedom concept has been introduced recognizing that a part has six degrees of freedom, three translations, and three rotations. The standard, being a product-definition standard, recognizes the fact that there are physical simulators but speaks in terms of the theoretical-datum feature simulator.
Drafting as per asme y14.5 2009 simulator#
The physical-datum feature simulator represents the collet or chuck that would be used on the shop floor. The theoretical-datum feature simulator represents the perfect geometry as a circumscribing cylinder for a shaft. It is a little confusing at first, but there are two types of datum feature simulators, theoretical and physical.
The term True Geometric Counterpart has been replaced with the term Datum Feature Simulator. There are many major enhancements and clarifications in the datum section.
Drafting as per asme y14.5 2009 software#
Caution is in order, however, to make sure inspection procedures and CMM software can handle these types of features. This small change was really needed and opens the door to many possibilities, especially in plastics and sheet-metal parts. In the new standard, a hex, square, cone, or other similar type of features can used as a feature of size and even as a datum feature as long as they are properly related with profile or other geometric controls. Irregular features of size are features other than a sphere, cylinder, or two parallel planes. The limits of size, Rule #1, has been expanded to include irregular features of size. The use of direct-tolerancing methods, limit dimensioning, and plus-minus tolerancing are used to control the size of features only. It has been revised to emphasize and encourage of use of basic dimensions and geometric tolerancing as the preferred method of controlling the form, orientation, and location of features. The standard is progressing in its use of geometric tolerancing. Below, we’ll outline a few of the major concepts. The expansions, revisions, clarifications, and term definitions are woven through the fabric of the document. The reorganization has made the geometric concepts much easier to read and understand. The sections in the standard have been reorganized to present the foundational principles first and then to build on these foundations. They should not be interpreted as coming from the committee. Readers should also note that what follows are the views of someone who has been a member on the ASME Y14.5 subcommittee for the past 25 years. In general, the major change to the standard is that users will find it much easier to use and understand, but the fundamental geometric concepts have not changed. The new ASME Y14.5-2009 standard is progressing forward and reflects the state of the art in industry today. But prospective users can benefit from general guide to some of the new changes. That said, it is impossible to address the implications of all the changes in a short article. This file type includes high resolution graphics and schematics when applicable. There are many changes, improvements, and enhancements in this new standard from the earlier 1994 standard. The M in the title of the old standard recognized the fact that it was metric compatible and was deemed no longer necessary, so it was dropped. It is a revision of the ASME Y14.5M-1994 standard.
(941) 383-4283, The new ASME Y14.5-2009 standard on dimensioning and tolerancing reflects a culmination of effort extending over 15 years. Revisions emphasize use of basic dimensions and geometric tolerancing as the preferred way of controlling the form, orientation, and location of features.