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Currently, most computer numerical control (CNC) controllers lack the function needed to compensate machining errors for free-form surfaces. The objective of this research was to enhance the accuracy and precision of the machined free-form surfaces of a workpiece using the mirror compensation method with the on-measurement data. By mirroring the points measured after semi-finishing, a new free-form surface for finishing machining can be automatically reconstructed. The surface can then be used to generate the cutting tool path to reduce the errors during finishing machining. In this research, three different types of surfaces were used for evaluating the proposed method. The results show that the proposed method reduced the standard deviations of the three surface geometries by 61%, 61%, and 32%, respectively. We also evaluated the tool radius modification method commonly used in the industry for error compensation and found that there is no substantial reduction on standard deviation. Therefore, the effectiveness of the error compensation method proposed in this research is evident.

The aim of this research was to develop an efficient and accurate method to fabricate a dental implant surgical guide. The surgical guide is adapted from the patient's vacuum-formed clear template with the use of a plate with three ceramic balls, a six-axis drilling machine and its fixture. The plate, with the ceramic balls used as radiographic markers, is glued to the template, and the patient bites this template during a CT scan. Then, the surgeon can plan the locations and orientations of the implants on the CT-based model in the dental planning software. The drilling information is exported directly to the computer-controlled drilling machine for subsequent drilling on the template to complete the surgical guide. This method allows the surgical guide to be made without any measurements, which reduces the fabrication time, but increases the drilling accuracy. The preliminary results show that the average location error was 0.31 ± 0.17 mm and the average orientation error was 0.53 ± 0.24°, which can be considered accurate in comparison with the results reported in the literature.

No abstract

The common way to perform five-axis machining is to generate the toolpaths by using CAM software, which usually considers only the interference between the tool and the workpiece. However, in the actual machining process, either the tool assembly may collide with the worktable, or one of the axes may travel over its limits. Once these problems occur, then readjustment of the setup location of the workpiece or the tool axis in the CAM software are needed to resolve the problems. Because both are based on trial-and-error, there is no guarantee that the readjustments will work. The objective of this research was to develop an algorithm to compute the domain where the workpiece can be set up without the mentioned problems. The algorithm first calculates machinable domains for all orientations of the tool axes along the toolpaths without traveling over-limit. The intersection of the domains, called initial machinable domain, is where the workpiece can be set up without traveling over the limits of the axes. The next step is to calculate the total interference domain where interference between the tool assembly and the worktable may occur. Subtracting the total interference domain from the initial machinable domain yields the machinable domain where neither over-limit nor interference between the tool assembly and the worktable will occur. Two cases are presented to demonstrate the feasibility of the proposed method. The results in both cases were verified by CAM simulation. The innovation of this research is to propose a method to compute the machinable setup domain which can directly show the setup location without the over-limit and interference issues during the machining process, especially the interference issue between machine components. In addition, it can eliminate the trial-and-error in CAM planning and make the setup domain visible, which makes it convenient and confident for the CAM engineer to determine the setup location.