In parts machining, process planning is typically conducted by skillful operators. The quality of machining is highly dependent on process planning, which determines the operation parameters, such as the operation sequence and cutting tool. To achieve high-quality machining without depending on the skill level of the operators, standardization of process planning is desired. Therefore, it is necessary to extract and generalize skills related to process planning. Furthermore, eye tracking technology is expected to visualize unconscious human behavior. In this study, eye tracking technology is adopted to detect the movement of the operator’s eyes and gather gaze data when understanding mechanical drawings. Gaze data are analyzed using a heat map and bubble chart to identify differences in eye movement according to skill level. The analyzed heat maps indicate that the gazes of the skillful operator are gathered because the operator focuses on the area that is strongly related to the quality of machining. The analyzed bubble charts also indicate that the skillful operator considers the machining process by checking annotations, then understands the shape, and finally verifies the numerical values of the annotations. From the results of interviews performed based on the analysis, the individual skill could be effectively extracted in detail, particularly the skill regarding the operation sequence. Furthermore, the acquired skills are incorporated into a computer-aided process planning system developed in a previous study. The operation sequence is modified to reflect the acquired skills. Machining experiments confirmed the effectiveness of adopting operators’ skills in process planning.

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