Cutting time in pocket machining for different tool-path approximation segments

Despite of the importance of cutting time in pocket machining for manufacturing cost prediction and process planning, its estimation is usually neglected and conducted dividing the total tool path length by the programmed feed rate. Nevertheless, driving the tool with a constant feed rate is, in general, not possible. We study the cutting time dependency with the tool-path curvature, type of interpolation (linear G01 or circular G02) and the distance between interpolation points (segment length). The study, conducted in two different milling machines, shows how shorter segments increase the actual cutting time, which is lower for G01 than for G02. According to the experimental results, we define a piecewise equation that estimates the real cutting time respect to the segment length and type (G1 or G2).