New Multimedia Geometrical Tolerancing Course

AbstractThe new application Geometrical Tolerancing developed for usage during lectures at technical universities as well as for the enhancement of vocational trainings for design, manufacturing and metrology engineers working in industry is presented. The application capabilities are shown and discussed on base of the selected screen shoots. The suggestive 3-D animations and multicolour drawings with intuitive user interface are employed to effectively familiarize the application user with definitions of form, orientation, location and run out tolerances. The tolerance zones for toleranced integral or derived features are clearly visualized and then shrunk to show particular deviations. The role of the datums and datum systems for establishing involved tolerance zones is explained in details. The restrictions for the part geometry imposed by specified maximum material requirement or least material requirement that combine requirements for size of the features of size and the geometrical tolerance to one aggregated functional requirement are shown. The concepts of the geometrical deviations evaluation by coordinate measuring techniques or workpiece verification by hard gauges are demonstrated for the selected tolerances with case studies

Geometrical Product Specification and Verification as toolbox to meet up-to-date technical requirements

The ISO standards for the Geometrical Product Specification and Verification (GPS) define an internationally uniform description language, that allows expressing unambiguously and completely all requirements for the geometry of a product with the corresponding requirements for the inspection process in technical drawings, taking into account current possibilities of measurement and testing technology. The practice shows that the university curricula of the mechanical engineering faculties often include only limited classes on the GPS, mostly as part of curriculum of subjects like Metrology or Fundamentals of Machine Design. This does not allow students to gain enough knowledge on the subject. Currently there is no coherent EU-wide provision for vocational training (VET) in this area. Consortium, members of which are the authors of this paper, is preparing a proposal of an EU project aiming to develop appropriate course

Can ISO GPS and ASME Tolerancing Systems Define the Same Functional Requirements?

Geometrical tolerances are defined in the ISO Geometrical Product Specification system that is used worldwide, but on the other hand, the ASME Y14.5 standard is used in American companies to define how far actual parts may be away from their nominal geometry. This paper aimed to investigate whether specifications defining acceptable geometrical deviations in one system can be transformed to specifications in the other system. Twelve selected cases are discussed in the paper. Particularly, two cases of size tolerance, three cases of form tolerances, one case of orientation tolerance, four cases of position tolerance (including position tolerance with MMR for the pattern of five holes) and, finally, two cases of surface profile tolerance (unequally disposed tolerance zone and dynamic profile tolerance). The issue is not only in the several different symbols and a set of different defaults, but also in the different meanings and different application contexts of some symbols that have the same graphical form. The answer to the question raised in the paper title is yes for the majority of indications specified according to ASME Y14.5 when new tools from the 2017 edition of ISO 1101 are applied

ISO GPS and ASME GDT standards – differences and similarities in definitions of measurands

Geometrical tolerances as tricky measurands are indicated. Crucial differences between the ISO and ASME geometrical tolerancing standards are discussed. It is demonstrated that, in many cases, both systems have different default rules. Moreover, for some identical graphical indications, interpretations are different. On the other hand, the standards contain similar arrangements in many cases. It is underlined that nowadays, due to the progressing globalisation, it is necessary to know these standards, bearing in mind that suppliers or customers specify requirements according to provisions from particular standards implemented in their companies. The above justifies the need for research exploring differences and similarities in both systems of standards. It is shown that the ISO GPS system standards, due to default independency principle, prefer to set production as cheaply as possible, while ASME, due to default provisions ( e.g. Rule #1, simultaneous requirement) puts stress on controlling product geometry more strictly, which is sometimes unnecessary

Assessment of the candidate suppliers’ fluency in ISO GPS standards essential principles, rules and indications

Many potential suppliers state that they are ready to produce components according to specified requirements as they are familiar with the ISO GPS system tools for dimensional and geometrical tolerancing. Regrettably, in many instances, this is not true. This paper discusses a survey developed to assess the geometrical dimensioning and tolerancing skills and results derived from this survey executed among 15 potential suppliers. The investigation aims to preselect potential suppliers and evaluate how much support the suppliers will require while also assessing the risks associated with placing an order with a particular supplier. The survey is based on the online test comprised of 27 closed-end questions used to identify strengths, weaknesses, and knowledge of a candidate supplier’s personnel. Five different answers are given for each question. The respondent shall indicate one correct answer. The inquiry is practically oriented. Most of the questions include drawings with indicated selected tolerance as well as drawings of the possible actual parts with exaggerated geometrical deviations. The associated question is whether an actual part is made according to the specification. The main conclusion is that most responders disclose a low level of understanding of the ISO GPS system. Urgent education is needed

Tolerances for aluminium alloy-extruded profiles according to EN 755-9 and EN 12020-2 versus definitions of tolerances according to the ISO GPS system

The inconsistencies between tolerances for aluminium profiles as specified in EN 755-9:2016 along with EN 12020-2:2016 and tolerance concepts defined in ISO 1101:2017 are demonstrated. It is shown that the standards defining requirements for extruded profiles have been developed without considering provisions in the ISO GPS system. A number of ambiguities in EN 755-9 and EN 12020-2 that were overcome in the ISO GPS system are shown. For example, broad application of plus/minus tolerancing for step dimensions does not provide unique verification of aluminium alloy-extruded profiles. It is pointed out that some terms univocally defined in the ISO GPS system are used incorrectly in both standards. It makes it difficult for a customer to verify on CMM whether or not extruded profiles satisfy the requirements specified in the order. Finally, significant changes regarding geometrical tolerancing in standards for the aluminium alloy-extruded profiles are proposed