The evolution of Geometrical Product Specification and Verification in the field of surface metrology and the challenges of its vocational training

Surface metrology is the science of the measurement on micro/nano surface which plays an important role in the control of the manufacture process of a workpiece and the prediction of its performance. In the last three decades, there is an evolution in the field of surface metrology, such as the emerge of many new data collection methods, the development of novel data processing techniques and the shift of characterisation technology from profile paradigm toward areal paradigm. Therefore, in the last 10 years, ISO have developed and released lot of new standard documents to standardise the specification and verification procedure of surface texture assessment in the framework of its technique langrage, i.e. Geometrical Product Specification and Verification (GPS). It empowers engineers with a richer and unambiguous language to detail their requirement with the less specification uncertainty. However, an engineer has difficulty to develop his/her skill in use this technique language due to the increase of its complexity and flexibility. To this end, an EC founded project is undertaking to develop e-learning platform and workshop to deliver the latest development of GPS to engineers. It will use the student-centred method which focused user friendly learning environment, the learning outcomes (i.e. skill and knowledge), self-directed learning etc. This three-year project will be completed at end of 2018. In the beginning of the project, it is of importance to develop a better understanding the challenge of training and user requirement. Therefore, this paper reviews the evolution of GPS in the field of surface metrology with highlighting the issues from training aspect. It explores the current ISO standard documents and training materials, together with a short review of education theory and practise in the information era. A survey has undertaken from industrial participants which outline the requirements of its main users. The outcome of this research maps the field of this training project

Explicitly representing the semantics of composite positional tolerance for patterns of holes

Representing the semantics of the interaction of two or more tolerances (i.e. composite tolerance) explicitly to make them computer-understandable is currently a challenging task in computer-aided tolerancing (CAT). We have proposed a description logic (DL) ontology based approach to complete this task recently. In this paper, the representation of the semantics of the composite positional tolerance (CPT) for patterns of holes (POHs) is used as an example to illustrate the proposed approach. This representation mainly includes: representing the structure knowledge of the CPT for POHs in DL terminological axioms; expressing the constraint knowledge with Horn rules; and describing the individual knowledge using DL assertional axioms. By implementing the representation with the web ontology language (OWL) and the semantic web rule language (SWRL), a CPT ontology is developed. This ontology has explicitly computer-understandable semantics due to the logic-based semantics of OWL and SWRL. As is illustrated by an engineering example, such semantics makes it possible to automatically check the consistency, reason out the new knowledge, and implement the semantic interoperability of CPT information. Benefiting from this, the ontology provides a semantic enrichment model for the CPT information extracted from CAD/CAM systems

Softgauges for surface texture

Surface texture plays an important role in the specification of a precision workpiece. However, the route of traceability for surface texture measurements is not well developed. One of the main technical obstacles is the lack of tools to check traceability of the software of surface measuring instruments and to estimate uncertainty contributed by the software. To this end, the concept of softgauges (i.e. software measurement standards) for surface texture has been introduced into the international standards. The presented thesis documents the realisation of softgauges for surface texture, which is a part of the National Measurement System in the UK. These standards, in the form of the reference dataset with reference results, have been developed by both simulation and experimental methods. The analysis of software uncertainty has been undertaken. These measurement standards have been used to verify both reference software(developed by the National Measurement Institutes) and commercial packages (developed by instrument manufacturers). In addition, the evaluation of the measurement uncertainty in workshop level has been carried on. These developed standards provided a novel route to demonstrate metrological traceability of most surface profile parameters. Currently, these standards are distributed via the internet by the National Measurement Laboratory (NPL) in the UK. These standards are also recognised by NIST in the USA and PTB in Germany, and these organisations would also provide a suitable vehicle to distribute of the results of this study

An Information Model for Surface Metrology

According to ISO standards, the specification and verification of surface texture includes an ordered set of operations. In order to reduce the specification uncertainty, it is of importance to model the significant information related to surface measurement. This paper documents the development of a XML-based information model for surface metrology. Traditional paper-based documents with unstructured data are intergraded into one structured data for surface metrology. Therefore, it limits the specification uncertainty and enhances the reproducibility of surface measurement

Software Measurement Standards in Surface Metrology: Basics, Concepts, Methods

This book documents the realisation of software measurement standards in surface metrology, as part of the National Measurement System in the UK. Those standards, in the form of the reference dataset with reference results, have been developed by both simulation and experimental methods. The analysis of associated uncertainty has been undertaken through a series of case studies. Some decision rules have been proposed to guide the use of software measurement standards. Those developed software measurement standards provided a novel route to demonstrate the metrological traceability for most surface profile parameters which has not been tried before. It is expected that this route could be implemented for demonstrate all surface parameters in further development. Currently, those standards are distributed via internet by National Measurement Laboratory (NPL) in the United Kingdom