Papers by Keyword: ELID (ELectrolytic In-Process Dressing) Grinding

Abstract: In this paper we analyze the forming mechanism of composite abrasive grains in oxide film on ELID grinding wheel surface, By using composition information and by taking advantage of microscale structure, we have investigated that abrasive grains surface is covered by a layer of oxide film and the fresh oxide film is loose and porous like turtle shaped crack when crushed and dried. The elements of oxide film consist of α-Fe2O3 with sphere grain of 5-50nm. This phenomena is demonstrated that the composite abrasive grains in oxide film is a compound structure which is centered by abrasive grains, with α-Fe2O3,Fe (OH)3 surrounded.

Abstract: This paper conducted a theoretical study on the generation and transformation mechanism of α-Fe₂O₃ in the oxide film and an experimental verification of the presence of it. Firstly, the electrochemical process of the generation and transformation of α-Fe₂O₃ in the oxide film was analyzed, followed by the measurement of the content of it in the oxide film using X-ray diffractometer.

Abstract: Electronic in-process dressing (ELID) grinding will be a main technology of ultra-precision grinding which has been widely adopted to the ultra-precision and high effectively machining of hard and brittle materials. This study puts forward a new environmental friendly bamboo charcoal bonded (BCB) grinding wheel and develops a new ELID grinding fluid. An oxide layer is mostly determined by the electric performance of grinding fluid in the experiment. This paper founds a model to forecast grinding fluid’s electric performance by BP neural network and MATLAB. This method can be used in developing of ELID grinding machining fluid to improve the ELID grinding effect.

Abstract: To cope with increasing demands on ultraprecision profiling and finishing of aspheric lens molds, we have implemented an ultra/ nanoprecision aspheric grinding system to be mounted with an ELID- capability and on-line feedback capability of profile accuracy. A WC mold has successfully ground and finished to be with several nanometric surface smoothness and with ultraprecise profile accuracy by just grinding process with ELID mechanism. Some specific conditions have been investigated to achieve better accuracy and quality on molds. This paper presentation introduce those R&D activities and also discuss on the latest achievements on this topics, with showing injected aspheric lenses by the molds.

Abstract: Compound micro-machining is the most promising technology for the production of miniaturized parts and this technology is becoming more and more important and popular because of growing demand for industrial products with not only increased number of functions but also of reduced dimensions, higher dimensional accuracy and better surface finish. In this paper, the development efforts in micro/nano-machining based on solid tools (tool-based micro/nano-machining) in NUS are introduced. In order to achieve meaningful implementation of micro-machining techniques, this research seeks to address four important areas; namely (a) development of machine tool capable to do both conventional micro-machining, (b) process control, (c) process development to achieve necessary accuracy and quality, and (d) on-machine measurement and inspection. An integrated effort in these areas has resulted in successful fabrication of micro-structures that is able to meet the miniaturization demands of the industry. In the area of nano-machining machine tool and process developments have also been carried out for electrolytic in-process dressing (ELID) grinding and ultra precision machining using single point and poly crystalline diamond tools to produce nano surface finish on hard and brittle materials. An ultra-precision diamond turning machine has been developed which incorporates a fast and fine tool servo system to produce nano-precision surfaces and features.

Abstract: Silicon is widely used as the most important substrate material in integrated circuit and micro electronic devices field. Electrolytic in-process dressing (ELID) grinding technique is an effective grinding process especially for machining hard and brittle material. In this paper, using super fine abrasive wheel, sets of ELID cross grinding experiment were conducted for investigating the influences of various grinding conditions including grain sizes, rotation speeds of grinding wheel, rotation speeds of workpiece and ELID conditions on surface roughness during grinding silicon wafers. Surface roughness characteristics of fine ELID cross grinding for silicon wafers were discussed. In an optimized condition, surface roughness of 2.2 nm in Ra can be achieved by using #20000 wheel.

Abstract: This paper reports a study on oxide film formation mechanism in electrodeless ELID grinding. The formation mechanism of oxide film was analyzed based on electrochemical principles, its formation model was built and the growth process was also simulated. The simulation results showed that the oxide film thickness h and its growth rate g are nonlinear functions of time t, voltage and duty cycle are important factors which take effect on g and h, and the electrodeless ELID grinding is a process of weak electrolysis and suitable to use micro wheel.

Abstract: A new BCB (Bamboo Charcoal Bonded) grinding wheel was developed by bamboo charcoal-phenolic resin composite under vacuum for ELID grinding technology. The pyrolysis behavior of the new bamboo charcoal-phenolic resin material was studied by thermo gravimetric analysis (TGA), and structural characterization of the new material was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), the friction characteristics was also investigated in this paper.

Abstract: This paper describes the current situation of spherical grinding for carbide material. The experiment of Concave spherical ELID grinding of generating method for carbide is conducted. Because dressing electrode can’t be installed in limited space due to the small space of concave spherical surfaces and carbide material has good conductivity, the workpiece material was used as dressing electrode in the ELID grinding experiment. According to negative effect of spark discharge in the process of grinding to surface roughness, two methods "ELIDⅡ" and "ELID Ⅲ" were designed. Comparing and analyzing the experimental results, it is confirmed preliminary that the spherical error and surface roughness of the workpiece after "ELIDⅡ" grinding were better than those after the "ELID Ⅲ" grinding. The ELID grinding method using micro diamond powder wheel and using carbide workpiece as dressing electrode is an effective way for spherical ultra-precision grinding for carbide.

Abstract: ELID (electrolytic in-process dressing) grinding was proposed by one of the authors for automatic dressing the grinding wheel while performing grinding for a long time. It offers a high effective way and has been widely used for grinding hard and brittle optical materials. However, those surfaces produced by fixed abrasive grinding are characterized by considerable sub-surface damage, micro-crack. Magneto-rheological finishing (MRF) is a novel precision finishing process for deterministic form correction and polishing of optical materials by utilizing magneto-rheological fluid. In this paper, an ultra-precision synergistic finishing process integrated MRF and ELID grinding is proposed for shorten total finishing time and improve finishing quality. A lot of nano-precision experiments have been carried out to grind and finish some optical materials such as silicon, silicon carbide, etc. ELID grinding is employed to obtain high efficiency and high surface quality, and then, MRF is employed to improve further surface roughness and form accuracy. In general, form accuracy of ~ λ/20 nm peak-to-valley (P-V) and surface roughness less than 10 Angstrom are produced in high efficiency.