A method to calculate tool path uniquely for roughing using a flat drill is proposed. A flat drill is a drill with a flat tip. Unlike a square end mill, it cannot feed a tool laterally, but it is suitable for machining to feed a tool longitudinally. The advantage offered by the flat drill is expected to reduce machining troubles, such as tool breakages and chatter vibration, owing to the axial sturdiness of the tool. Furthermore, it can be used to machine lapped holes that cannot be machined with a normal drill owing to its flat tip. Hence, roughing using a flat drill by drilling multiple holes at constant intervals is proposed herein. Furthermore, in this method, a tool path for semi-finishing is generated only on the remaining region. A cutting experiment is conducted to validate the effectiveness of the proposed method. The result of the cutting experiment confirmed the effectiveness of the proposed method based on the machining time and the productivity of machining multiple products simultaneously.

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