Development of Production Planning Method to Reduce Setup Time on Bending Process in High-Mix Low-Volume Production

To realize efficient production, it is important to reduce the setup time, especially in high-mix low-volume production where the setup time is mainly spent to switch product categories. Group technology can reduce the setup time by processing parts with the same setup in the same group. However, in high-mix low-volume production, it is difficult to create large groups because there are many product categories. To address this problem, this study aims to extend group technology to create large groups with various product categories. We hypothesized that the setup conditions can be categorized into changeable and unchangeable parameters, allowing large groups to be formed by standardizing different setup parameters to the same value. Based on this hypothesis, we proposed a method consisting of four steps: creating groups using unchangeable setup parameters, ordering in a group to minimize differences in changeable setup parameters at each gap, changing changeable parameters to minimize setup time, and ordering among groups to minimize setup time. This method was validated using two sheet-metal-bending machines. Applying the proposed method reduced the setup time from 841 s to 680 s, which indicates that the proposed method is effective for setup-time reduction. To facilitate the straightforward application of this method, we will explore ways to categorize parameters as changeable or unchangeable.