Papers by Keyword: Stock Removal

Abstract: A pressure sensor is developed to explain the finishing mechanism in centrifugal disc finishing. The distributions of the flow pressure of mass in the radial direction and the height direction of the barrel are investigated. The flow pressure of mass is higher in the lower layer near the disc than in the upper layer, regardless of the finishing conditions. In the upper layer of the mass and near the side wall of the barrel, the flow pressure of the mass of the wet process is higher than that of the dry process. However, the stock removal of the dry process is larger than that of the wet process.

Abstract: The micro patterning on a cylindrical surface is conventionally carried out by electrochemical machining, chemical etching, cutting and so on. However, there exists some problems in machining dimensional errors and tool lives. On the other hand, blasting is expected as one of micro fabrication methods and progresses to apply for machining of hard and brittle materials. The purpose of this study is to develop the micro blasting technique for patterning of micro herring-bone grooves on spindle surfaces of the fluid dynamic bearings. Then, machining characteristics in blasting of rotating workpieces are experimentally investigated, analyzing stock removals, burr heights and groove shapes. In addition, micro herring-bone grooves are patterned on spindle surfaces by blasting and the performance of herring-bone bearings are evaluated. The herring-bone bearings with micro grooves patterned on a spindle surface by blasting have enough performance, compared with conventional ones.

Abstract: Micro patterning on cylindrical surface, e.g. dynamic pressure bearings, is mainly carried out by chemical etching. However, there exist environmental problems in the waste etchant processing and safety ones in works using toxic chemical liquids. On the other hands, blasting is expected as one of micro patterning methods and comes into use for not only surface modification but also machining of hard and brittle materials. The purpose of this study is to develop the micro blasting technique for cylindrical parts. Therefore, machining characteristics in blasting of rotating workpieces are experimentally investigated, analyzing the stock removal and the surface roughness. In addition, the patterning of micro herringbone grooves are carried out on spindle surfaces based on the obtained characteristics.

Abstract: For the improvement of the performance in centrifugal disc finishing, the flow-through system for supplying the compound solution is tried and its influences on finishing characteristics are experimentally investigated. Workpieces (22 mm in diameter and 15 mm in thickness) of plain carbon steel (S45C in JIS), aluminum alloy (A2017) and copper alloy (C3604) are finished with ceramic media (Equilateral triangular prism 6 mm in side and 5 mm in thickness). The conclusions are summarized as follows; The compound solution has more influences on finishing characteristics than plain water. It makes the relative stock removal larger and the surface roughness smaller than the water. The relative stock removal and the media weight loss on the flow-through system are larger than those on the batch system.

Abstract: The purpose of this study is to develop the cavitation aided abrasive machining which makes effective use of cavitation occurring in suction flow of slurry for fine machining. In this paper, a fundamental machining phenomenon of glass using the cavitation suction flow is clarified and machining characteristics are experimentally investigated by the observation of machined surface and surface roughness, stock removal and cavitation impact. Abrasive grains impinge on a workpiece surface to physically remove work material and generate fine surface in the machining. Then it can finish the polished glass surface of 9.3nmRz down to about 5.0nmRz by using abrasives of WA 4000.

Abstract: The speed-up of the disc rotation in dry centrifugal barrel finishing is done and its influence on finishing characteristics is experimentally examined. The workpiece is a sliced cold rolled bar of plain carbon steel (S45C in JIS, HB221). It is 32mm in diameter and finished to10mm in thickness by belt grinding. The equilateral triangular prism nylon media (
1010mm, A#320) is used at 20vol% in media charging ratio. The disc rotation speed is increased up to 500min-1. By speeding up the disc rotation, the finishing speed improves, but the total efficiency decreases.

Abstract: The miniaturization of semiconductor devices is advancing rapidly. The requirement for wafer flatness is becoming increasingly stringent as the use of shorter wavelengths in the latest laser lithography results in a smaller focusing depth of field. In our research, a flatness of 0.1 µm has been achieved over an entire 12" wafer surface by planarization with oscillation speed control type polishing. However, in addition it is necessary to increase the removal rate in order to reduce the polishing time. Although high rotational speed polishing is a solution to meet this requirement, the polishing characteristics change with the rotational conditions. Using a simulation program, we calculated that the stock removal saturates as the rotational speeds of the wafer and polishing pad are increased beyond a certain point. Also, experimental results showed that at high rotational speeds actual stock removal is significantly less than that indicated by the simulation, and that too much slurry causes unnecessary etching.