Quality in Manufacturing and Geometric Tolerancing
Research focus
The Peer review has evaluated this group as Good
During the last decades, we are assisting to a renewed attention to enhance product and process quality. Indeed, the focus on quality rather than on costs, can be firstly ascribed to the increasing role of countries characterized by low labour costs (e.g., China, India) in the worldwide competition. In order to achieve high quality performances, product specifications should be properly designed, measured and manufactured. Therefore, research on quality should be aimed at improving all the activities related to tolerancing, metrology and quality monitoring and control, by adopting an integrated point of view. The research interests of the group focus on these three main topics, as detailed in the following. Tolerancing Research work in this area aims at developing formal procedures and software tools which may enhance the consideration of accuracy constraints in product design. The common approach to these methods is a detailed modeling of manufacturing errors and tolerance requirements with respect to available geometric descriptions of parts and assemblies. Solutions have been proposed on a wide range of tolerancing problems: - generation of tolerance specifications from geometric product information, with automated identification of manufacturing requirements; - calculation of geometric tolerance stack-ups through statistical formulation and integration of tolerance analysis in computer-aided design through implementation of a variational approach based on solid modeling; - analysis and optimization of locating schemes for workholding fixtures in order to reduce the accumulation of errors from datums to machined features; - control of the surface finish of parts manufactured by rapid prototyping processes through an optimization of build orientation and a direct texturing of geometric models. Geometrical Metrology The activities in this domain aim at the development of a Computer Aided Inspection Planning system able to automatically plan all the operations related to geometrical inspection of mechanical components by coordinate measuring machine (CMM). A CAIP system gets information from a solid model representation of the component, enriched with tolerance information, and makes decision in order to generate a complete CMM inspection plan. Particularly, in the last years it has been tackled the problem of sampling strategy definition starting from the consideration that the real geometry of a part is directly related to manufacturing processes. The issue of identification and use of the geometric signature left by a process on a manufactured part has been studied. The signature identification problem is very close to reverse modelling problem. This fact has brought to new studies in freeform shape reconstruction and verification. In particular, it has been explored the use of particular classes of spline, namely lambda spline and regression spline, never applied before in this domain of application. Quality in manufacturing Recent developments in automated inspection and computerized data analysis represent an opportunity to enhance quality performances by overcoming traditional approaches for process monitoring and control. With reference to process control (or adjustment), where the main objective is to quickly detect and compensate for deteriorated process performances, the research focuses on new techniques for setup process adjustment. Setup errors can arise from different sources (improper tool or fixture settings, different characteristics of the material processed in batches, operator errors etc.) and should be properly compensated for to avoid poor quality of product processed. With reference to process monitoring, where the main objective is to quickly detect deteriorated process performances, the research focuses on new approaches based on neural networks and adaptive Bayesian control charts while a recent field of interest is devoted to new approaches for monitoring quality characteristics which are related to geometric features (e.g. roundness, cylindricity, planarity, etc.) Eventually, minor research activities have been devoted to service quality and to the use of forming limit diagrams to better foresee defective items in forming. On this research areas the group is strongly connected to other Italian university (particularly with the University of Lecce and University of Cassino) and has a relevant collaboration with Prof. E. del Castillo of Pennsylvania State University - PSU, USA. The experience in integrating design and manufacturing and in CAIP system developing is the main motivation for the most relevant private funding received by the group in an apparently completely different topics: the development of a computer aided process planning system for sheet metal die machining and assembling.
Dipartimento di afferenza
Docenti afferenti
Full Professors
Giovanni Moroni
Quirico Semeraro
Associate Professors
Antonio Armillotta
Bianca Maria Colosimo
Assistant Professors
Marco Rasella