Sensory perception of surfaces quality - Industrial practices and prospects

In this paper we carry out a critical analysis of the industrial practices used by the partner firms to control a product's aspect. The group of partners represents many different sectors of activity such as: luxury goods industry, furniture industry, medical equipment (prosthesis), plastic injection and watch-making industry. These practices deal with the identification of aspect anomalies, the evaluation of anomalies severity as well as the decisions about the product's conformity. We will show that current practices do not allow us to decrease the variability of the results frequently observed, because the subjectivity often associated with this kind of control is not eliminated using such methods. In every sector studied, we find the same dissatisfaction about the results obtained. We will then present our approach to sharply decrease this variability. This approach, tested in a famous Swiss watch-making company, is based on sensory analysis concepts. This approach is original due to the breakdown of the visual-control process into three sub-processes: the detection of aspect anomalies, the evaluation of those anomalies and the conformity decision. This approach also includes a metrological organisation and some tools which allow us to measure the efficiency reached. The paper will show how our approach succeeds in meeting the different aims of the partner company group and proposes an initial structured approach for a generic metrological organisation adapted to control the variability during the surface quality control by humans.