The double sided polishing technique is often applied to achieve high total thickness variance (TTV) of large silicon wafers that are employed to manufacture integrated circuit (IC) cards and smartphones. However, the theoretical analysis of high TTV is not sufficiently studied for the double sided polishing. Whereas, a polishing simulation for single sided polishing based on the gap theory was already developed. This simulation results were compared to the experimental results and indicate good behavior characteristics. This study presents a description of the theory for analyzing pressure distribution for double sided polishing and the simulation results of the surface generation process. It was demonstrated that the average of total running distance is nearly equal for the upper and the lower plates. Improved flatness is obtained when the rotation speed differences of the upper and lower plate rotations for the carrier revolution are equal. Furthermore, it was shown that TTV of less than 0.04 μm with a flatness of less than 0.05 μm may be attained when the cone upper plate with the optimum slope and the flat lower plate are employed with lower carrier rotation.
In-situ analysis is demanded for the investigation of a larger amount of rock samples in future lunar and planetary explorations. Because coolant cannot be used in vacuum environment, tool life will shorten. It is expected for wire-sawing to keep cutting performance due to successive supply of cutting edges in vacuum. The cutting performance was experimentally investigated under various machining conditions such as a wire feeding speed, cutting load and ambient pressure. Cutting debris adhered around grits on a saw wire in vacuum. In addition, nickel bond of the saw wire was adhered onto a rock surface. Then diamond grits slipped on the rock and cutting amount was decreased with a decrease of the vacuum pressure. The wire feeding speed below 1 m/s did not affect the cutting performance and the cutting depth was increased with an increase of cutting load. Saw wires with exposed grits was compared with a nickel-coated one. The cutting depth with the exposed saw wire was larger than that with the non-coated one. The wear of both the saw wires was almost the same. In addition, amount of grit wear was almost the same both in vacuum and air. The non-coated saw wire was preferable for vacuum use rather than the nickel-coated one.
This paper proposes a method for determining a high accuracy posture for serial redundant manipulators with parametric uncertainty that suppresses the effect of the uncertainty. In the proposed method, the uncertainty variance is introduced as an index for quantifying the magnitude of the distribution of the end-effector coordinates of the manipulator caused by the uncertainty, and the posture is determined by using the uncertainty variance as an evaluation function of posture. In order to efficiently calculate the uncertainty variance, the method includes a calculation method based on the polynomial chaos theory. The effectiveness of the method is confirmed by a posture determination simulation of a serial redundant manipulator with uncertainty. In this simulation, it is confirmed that the calculation of the uncertainty variance can be achieved by the method using the polynomial chaos theory, and that the proposed method can determine the high-accuracy posture that suppresses the effect of the uncertainty.