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Geometrical features are fundamental elements for the fulfilment of the functional product requirements. Therefore, their inevitable deviations caused by manufacturing inaccuracies are the main issues in the field of tolerance management. To close the gap between physical part description and nominal model representation, the framework of discrete geometrical representatives via Skin Model Shapes has been developed and continuously enhanced. As the underlying concepts are based on final virtual parts, consistent inferences to every single manufacturing step are not fully investigated in literature. This paper presents the development of Skin Model Shapes based on the virtual representation of intermediate part outcome (in-process geometry) and the integration of machining processes. Thus, integration and simulation of different kinds of deviations are enabled at each manufacturing stage considering error accumulation due to machine specific inaccuracies, such as tool movement and fixturing. Furthermore, the effect of inaccuracies on the final conformance result can be quantified at each manufacturing stage. A case study is presented to illustrate the entire approach and to demonstrate the validity of the proposed methods.

For more than 25 years, the aim of the Geometrical Product Specification (GPS) system has been to establish a consistent framework for specification and verification of geometrical properties ensuring the functional requirements placed on a product – unambiguously, completely and non-verbally. In order to get to know the system or to learn how to use it, it is common for selected employees, mostly designers or developers, to receive training courses lasting several days. The majority of the currently 150 existing individual standards are presented in an overview while the extensive symbol language is explained and applied to fictitious examples. Though, because of a lack of efficient teaching courses, it is almost impossible for the technical experts to use the GPS system in practice in its entirety. Furthermore, all far-reaching cuts in all product development processes, including the interfaces considering the internal and external customer supplier relationships, are still not understood sufficiently. There is no user-friendly procedure for integrating the GPS system into companies and assessing the progress of application, up to now. This paper describes the approach of a GPS integration based on a maturity model. The aim is to enable companies to integrate the GPS system into the entire product development process using agile methods and to develop themselves into learning organizations.

In this paper the process of integrating the information of real and simulated measuring data into the early development stage and its potential benefits are presented. Thereby existing concepts of closed loop tolerance engineering are considered and expanded with geometrical aspects. As a result, the reverse process flow and interactions of the different product development stages are achieved. Criteria for the establishment of consistent data flow like independency of the used design software and measuring system as well as data exchange format are introduced. During the design stage of a product, decisions are made with a strong impact on functionality and manufacturability. Therefore, guiding the designer within this process is necessary to reduce ambiguous, uninformed and incomplete specifications. With the focus on gathering information from previous products, prototypes and early production stages the definition of the products can be optimized and waste can be reduced. With the integration of measuring data in simulations, what-if analyses and discussions, the mainly forward-facing process in product development can benefit from a reverse information processing and therefore become a closed loop process for design, tolerancing, process development, prototyping, production as well as measurement. Existing standards defined in the ISO Geometrical Product Specification system (GPS) for the specification of geometrical properties can be used to support this with the rules and structures developed for geometrical elements.

Abrasive flow machining is a suitable manufacturing process for deburring, edge rounding and surface finishing applications. In this paper, the alterations of the form as a result of abrasive flow machining are presented. The alteration of the form is only one example for the reproduction of geometrical changes. Others could be seen in the changes of surface roughness or waviness. Moreover, a verification strategy for a holistic understanding of the interaction between the micro and macro geometry is introduced. In this sense, the term quality is enhanced. The findings are used to develop process models and simulations in consideration of the correlation between the machining parameters and the examined geometrical properties. These process models will be used to accelerate the process design, thus reducing costs incurred by time, work and material for necessary experiments.

Der Artikel beschreibt die Nutzung der VR-Technologie zur Unterstützung und Optimierung von Qualitätsmethoden. Die Anwendung von QM-Methoden, hierbei im Speziellen der FMEA, kann durch die Nutzung der Virtual Reality unterstützt und verbessert werden. Die FMEA, als eine wichtige präventive QM-Mathode zur Fehlervermeidung, wird besonders gut unterstützt, da bei dieser Methode die Visualisierung des Untersuchungsobjekts ein entscheidender Schlüsselfaktor für das Ergebnis ist. Besonders vorteilhaft ist die Nutzung der Visualisierung durch die VR bei Produkten, welche durch Ihre hohe Komplexität nicht als Prototyp bzw. nur mit sehr hohem Aufwand als Prototyp erstellt werden können.

In applying quality management (QM) methods, as for instance the Failure Mode and Effects Analysis (FMEA) in the field of complex mechatronic systems, it is necessary to visually illustrate the system to be examined to all members of the interdisciplinary team. Using Virtual Reality (VR) in combination with QM methods creates conditions that help the team to improve the application of QM methods considerably. VR is particularly suitable to visualize complex mechanical systems due to its realistic three-dimensional presentation of single components, assemblies, and complete systems in combination with the interaction in all six degrees of freedom. The present article presents goals and results of a research project at Chemnitz University of Technology. One result is that all members of the interdisciplinary team easily gain insight into the stage of development when FMEA is supported by Virtual Reality.

Zusammenfassung Der Beitrag stellt die Ergebnisse eines Ringvergleiches zur Messung plateauartiger Nano-Strukturen auf einer gewachsenen Siliziumoberfläche mit verschiedenen taktilen und optischen Messgeräten vor. Die Strukturen sind Inseln mit einem Durchmesser von ca. 800 nm und einer Höhe von ca. 12 nm. Neben der vertikalen und horizontalen Ausdehnung können damit Auflösung, Sensoreigenschaften, Stufenhöhen und auf Grund des ideal ebenen Grundmaterials auch die Geradheiten von Führungsbahnen im Nanometerbereich kalibriert werden.

Zusammenfassung Die funktionalen Eigenschaften von tribologischen Systemen sind mit den heute genormten Kenngrößen für Form, Welligkeit und Rauheit auf Grund der Vorgehensweisen bei der Erfassung, Filterung und Zuordnung nur eingeschränkt zu bewerten. Ausgehend von einem einhüllenden Bewertungssystem werden neue Möglichkeiten der Beschreibung der Interaktion der geometrischen Oberflächeneigenschaften für tribologische Systeme vorgestellt.

For functional properties such as gliding, sealing, assembling, adhering etc. the outer layer of the surface is the functional related surface. For the functional assessment of the surface this outer layer should be used as the reference for any functional characteristic. With the existing mean line system for the assessment of roughness and waviness, the standardized characteristics do not follow this logic. However there are valid historical reasons for the acceptance of the shortcomings of the mean line system. They are e.g. the alignment of the profile, the removal of form, the assumption of a sinusoidal structure of the waviness on the surface, and the distortion of the surface by the application of the mean line filtering process. To overcome these shortcomings morphological operations have been used to establish a new developed envelope system. In order to define new parameters to characterize and specify functional properties of surfaces, a common datum is necessary. The presented method for the alignment of datums is consistent with the algorithms used to establish datums and datum systems for workpieces, where the datum is established by the location of a tangent geometrical element such as a line, plane, cylinder etc. The orientation is usually derived by the application of the minimum zone algorithm. The benefit of the assessment of the functional properties of surfaces with morphological operations will be presented for two examples.

Common functional requirements of work pieces are sliding, adhering, sealing and assembling. These requirements are asking for specific properties of surfaces. Surfaces of work pieces are described by geometrical properties such as dimension, orientation, form, waviness and roughness. Functional requirements need to be expressed by specifying these geometrical features. With the existing definitions for orientation, form, waviness and roughness a holistic description of functional surface properties is not possible. Based on the function a holistic view of the surface properties including dimension, orientation, form, waviness and roughness is necessary. The existing classification of the surface based on wavelength is in combination with the mean line filtering an incomplete definition. The dimension and orientation of the work piece geometry is not even considered. With the revitalization of the envelope system there is a new approach to establish a correlation between the functional requirements and geometrical properties of the work piece surface. This new approach consists of the implementation of morphological filter operations to associate dimension, orientation, form, waviness and roughness based on a common reference system. This common reference system is equal to the envelope of the work piece. Proposals to describe the functional requirements with new parameters are presented.

The basic problem of measuring real surfaces with a tactile probe is the distortion of the measured profile due to the tip geometry in comparison with the real profile. The bigger the ratio of the characteristic dimension of the tip and the shortest describing wavelength of the surface, the larger the relative distortion will be. That must especially be taken into account in the case of the measurement of nano structures. To reverse this distortion a morphological operation for the reconstruction of the mechanical surface is investigated. The results demonstrate the efficiency and the limits of the reconstruction to obtain the mechanical surface, which also depends on the morphological extraction theorem.

In ISO 5459: 1981 the problem of datums and datum-systems established by cylindrical features is described graphically. The figures in the standard, however, show solutions that sometimes are not unique irrespective of the realization with hard gauging or by using algorithms. In order to develop algorithms to solve the above mentioned problems, well known ideas of hard gauging have consequently been applied. For the example of cylindrical features unsolved problems will be discussed. Proposals for the cases of maximum inscribed and minimum circumscribed geometrical elements will be presented. In addition the problem of common axes of two or more cylinders with any diameters is covered. The new concept is generic to solve all possible cases including the ones, which can not be solved by applying algorithms used today. The results obtained by the new concept are consistent with the solutions found by hard gauging.

According to international standardisation, the functional requirements are the basis for the specification of geometrical properties. The planning of measurements is deviated from these specifications. Furthermore, characteristics of production processes are not represented in the specifications and measurements. Therefore high risks of product quality problems are preassigned. Especially in the context of increasing digitisation and communication of production machines, the potential to control the production with help of measuring data is not prepared. Major benefits in quality as well as costs can be evolved by uncovering this potential. This paper shows a possible solution for the intelligent use of measuring data for production control. For that it is essential to create a system which starts from the functional requirements and also includes manufacturing processes properties to identify the relationship between measuring results and the process parameters. This new understanding will lead to an early planning of measurements with a higher effort at the beginning of the development process to generate effective and specific measuring data but will reduce time and costs as well as better quality at the end. That is the fundament for the industrial development and a smart production.

The paper presents the possibilities and advantages of collaboration platforms for the quality information management of the advanced quality planning. This is based on a quality information system that provides all information necessary for the specification and the control of product and process conformity. The goal of this quality information management is the reduction of changes after the development process as well as a back flow of information for a sustainable product development process to save money and resources.

The recent attempt in Geometrical Product Specification to change from dimensional to geometrical tolerancing leads to a stronger focus on datum systems. Two aspects on the requirements for these and their effects on each other will therefore be discussed in this paper. A new approach to develop a functional datum system in the early stages of the methodical design process that is derived from the functional interaction of the indeterminate workpiece geometry within the outlined assembly group will be explained. It will also show current research results to overcome the gaps in ISO 5459 about extraction and association requirements for the verification process.