Investigation of cognitive strain during visual inspection of cutting tools

A cutting tool, manufactured from a hardened metal, is used to cut, shape, and remove material from a workpiece in machining processes. It is directly in touch with machined workpieces and usually determines the machining quality. Therefore, to enable precise machining and long tool life, quality tests are required in the production process of cutting tools. Visual inspection is one of the Non Destructive Tests (NDT) that is also utilized to identify any crack or damage, minimizing scrapped items and rework. A magnifying system can be used to monitor and detect the defects in microscopic dimensions of the cutting tools, even with complex designs and various sizes. The acceptance/rejection decision is given by the quality control staff, based on standard procedures or based on experience.
The main aim of this study is to attract attention to the difficulty of defect searching and decision-making processes in visual inspection. The visual inspection process at a cutting tools manufacturing facility is considered. During the tests, eye movements were monitored with a mobile eye tracker; cognitive loads were evaluated with the NASA-TLX method, then thoughts and opinions about the tasks performed by the participants were collected with the think aloud protocol. Based on the task performances, the experience level of the participants was identified to be significant.
The results of the study confirmed that using new technologies such as eye-tracker can help to record various data to identify significant factors in visual inspection. By this means, the know-how of experience of inspection staff can be utilized in training novice staff to minimize related inspection costs and optimize inspection in a time pressure environment.