## 1 Introduction  
There are many kinds of products produced with Computer Numerical Control (CNC) machine tools. According to the workpiece weight, geometric shape, material, tools, and cutting conditions, the operator needs to estimate the proper manufacturing processes, so the machining requirements will not be the same. Some products require an extremely smooth surface, such as plastic injection molds, while others require high geometrical accuracy and little tolerance, such as precision machine elements (cf., gears), and still others require high cutting efficiency (i.e., material removal rate) and allow larger tolerance, such as the aluminum brackets for bicycle or aerospace. This situation is why machine tools have focused on how to accomplish high-surface-quality (HQ), high-accuracy (HP) and high-speed (HS) machining. Most of the commercial CNC machine tools are equipped with a standard set of CNC parameters, which are not changed according to the different machining demands. The standard set of CNC parameters of machine tools are created by their manufacturers. However, the tuning of CNC parameters has to require a lot of domain knowledge, including the most basic theories, such as statics, dynamics, kinematics, mechanism, motion control, etc. More advanced knowledge also includes the quality of Computer Aided Manufacturing (CAM), interpolation, machine performance, tool geometry, cutting conditions, etc. That is why the machine operators cannot easily tune the CNC parameters to match their product for relevant machining requirements. Figure 1 shows the architecture of feed motion processing sequence in the commercial CNC machine tools in this study. Firstly, the CAM model generates the corresponding Numerical Control (NC) code. The position command of the NC code (\(S_{g}\)) would be interpreted by the CNC controller for tool-path planning in interpolator, and that generates the motion trajectory based on the CNC parameters. Therefore, the CNC parameters include the velocity, acceleration, and jerk for their path statements, such as straight, corner, and arc paths. An algorithm on the tool-path planning produced the kinematic profiles of their relevant position, velocity, acceleration, and jerk based on NC code and CNC parameters. According to the kinematic profiles, each servo axis would move along the trajectory motion that was defined as position command (\(S_{c}\)). The \(S_{c}\) drives the feed drive system of the machine tools via servo loop. The feedback signal was defined as the actual position (\(S_{a}\)) for the feed drive system in the machine tools. Finally, the real workpiece would be produced based on the tool path, tool, material, and cutting conditions. The loop of the blue arrow in Figure 1 has been widely used in all machine tools. The goal of this study was to analyze the relationships among machining modes, CNC parameters, and dynamic errors, followed by developing the tuning procedure which can tune the proper values of the CNC parameters to match the selected machining mode; it is shown on the red dot frame in Figure 1. Firstly, an analysis of the CNC parameters based on algorithm of tool-path planning in the conventional controller, and the principle of tool-path planning was organized. It proposed the dynamic errors chain that we have to observe in actual machine tools. In this paper, dynamic errors signify the deviation between the position of the NC code and the actual position of the feed drive  
Figure 1: The goal architecture of the processing sequence in this study. system. It contains two parts: One part is the difference between the \(S_{g}\) and \(S_{c}\), another part is the difference between the \(S_{c}\) and \(S_{a}\). Secondly, we experimented on the machining modes with different CNC parameters and collected data. It presents a tuning criteria for the three machining modes and CNC parameters. Finally, this study adjusted the CNC parameters and analyzed the experimental results with an actual machine to develop the tuning methodology for machining modes.