Papers by Keyword: Polishing

Abstract: This study deals with automation of polishing process by using an industrial robot. In polishingprocess, full automation of polishing operation has not been achieved due to the difficulty invisual inspection. Judgment of whether polishing is sufficient or not has been performed by skilledworkers. In this study, the polishing after milling process is targeted. In the previous report, the generationof robot program for polishing operation based on CAD data was already proposed. Focusingon the periodicity of cutter mark patterns on milling surface, we proposed an automatic judgment ofpolished surface quality based on the image processing which uses Discrete Fourier Transformation.In order to capture images of polished surface, a CCD camera was mounted at 6-axis controlled robothand. However, the image processing method proposed in previous report could not judge the curvedcutter mark patterns because the periodicity of those patterns is not uniform. The objective of thisreport is the development of automatic judgment method for non-periodic cutter mark patterns. Wedeveloped judgment method which uses pattern recognition as a mean to judge existence or not of cuttermarks. As a result, the developed system allows the automatic polishing that includes the surfacequality judgment.

Abstract: Single crystal SiC is one of the most attractive semiconductor materials for next generation power device applications. However, it is very difficult to be precisely machined due to its high hardness and chemical inertness. We evaluated the machining characteristics of 4H-SiC using different processes including diamond abrasives lapping, chemical mechanical polishing (CMP) and plasma assisted polishing (PAP). Scratches were introduced through diamond abrasives lapping due to the high hardness of diamond, which resulted in the worsening of surface roughness. A damage layer was observed in the cross-sectional transmission electron microscopy (XTEM) images. A scratch-free surface was obtained through CMP, but it’s not atomically flat since step/terrace structure couldn’t be clearly observed. PAP was newly proposed for the finishing of difficult to machine materials. In PAP, water vapor plasma oxidation and soft abrasive polishing were repeatedly conducted. Ceria which is much softer than SiC was used as the abrasive material. PAP was proved very effective to achieve surfaces out of scratches. Also, due to the low hardness of ceria, no damage layers were introduced. The roughness of PAP processed surface was decreased to about 0.1 nm rms. The surface was also observed by XTEM, which proved an atomically flat surface without crystallographical damage was obtained.

Abstract: Micro-aspheric lenses molded by micro-aspheric ceramic molds are increasing in the optical systems such as digital cameras and blu-ray players. To finish the molds with high accuracy and low surface roughness, in this paper, the micro-aspheric mold made of Electroless nickel plating are polished by using the newly developed 5-axis magnetostrictive vibration-assisted polishing machine. The magnetostrictive vibrating polisher generates a lateral vibration at 9.2 kHz with amplitude of 30 μm. The polishing pressure is controlled by a balance adjustment mechanism and the polishing load is controllable within a range of 2 mN ~ 20 mN with a resolution of 2 mN. The motion resolution of the X-Y-Z table is 0.1 μm in each direction. The C-axis rotary table is mounted on a B-axis tilting table and the workpiece is mounted on the C-axis rotary table with a vacuum chuck. According to the polishing experiments, the form accuracy was improved to 200 nm P-V and the surface roughness was reduced to 10 nm Rz (1 nm Ra).

Abstract: In order to meet the needs for the precise polishing of free-form surfaces, a new compliant polishing tool system was designed based on a magnetorheological torque servo (MRT), and integrated into a CNC milling machine. Through analysis, it was pointed out that the key factor affecting the polishing quality of this system is the stability of the system. By means of the 3D geometric modeling software ProE, the finite element analysis software ANSYS, and the dynamic simulation software ADAMS, the rigid-flexible mixed model of the system was established and the stability of the polishing pressure and tool position was numerically analyzed.

Abstract: We report preliminary results from an on-going study investigating the effect of fixing workpieces within the media flow field contained in a typical vibratory finishing bowl. To this end, we studied the surface roughness evolution over the surfaces of workpieces with generic geometries such as cylinders. A granular flow dynamics model applicable to dense granular flow and a previously derived process equation were invoked in order to respectively describe the flow of the abrasive media; and the roughness distribution in terms of the granular pressure and velocity. By solving the granular flow field for the pressure and velocity distribution on a given geometry using a general purpose computational fluid dynamics (CFD) code, we were able to analyse changes in surface roughness distribution from the process equation. The immobilized cylinders were submerged in the top portion of the media flow field so as to facilitate comparison between media flow past the workpieces as experimentally observed and as predicted by the CFD simulations. We conclude with an analysis, based on both experimental and predicted results, of the way in which media flow direction biases the surface roughness distribution on an immobilized cylinder.

Abstract: Silicone oil based magnetic compound fluid was prepared to polishing stainless steel in this paper. The new fluid consists of nano-sized magnetite particle, micro-sized diamonds, micro-sized iron particle and α-cellulose. The characteristics of the fluid were analyzed. The length and quality of the magnetic cluster in the compound fluid was observed under a magnetic field. Polishing experiment of stainless steel was conducted using the silicone oil based magnetic compound fluid on an inclined polishing finishing device. The micro morphology of the stainless steel’s surface was measured. The results showed the surface quality was improved remarkably and the final roughness of the surface was Ra (Average roughness) 0.020μm.

Abstract: Assuming that during the machining of stoneware tiles by flat grinding each grain on the abrasive wheel performs a single scratch, it is possible to simulate and analysis the effect generated by those employing esclerometry. This paper studied the effect between parallel scratches during brittle machining of stoneware tiles. Scratching tests were performed employing a CNC esclerometer; a Vickers indenter as abrasive tool; load of 10N by dead weight; three different configurations of sense in the same direction; three different configurations of spacing between the scratches incremented with a factor of 0.8, 1.0 and 1.2 times the average scratch width. The test samples were analyzed by optical microscopy and subsequent digital image analysis to quantify the worked area. The results showed variation of material removal as a function of the sense and spacing configuration. The sense configuration 1^st R-3^rd R-2^nd R had the highest improve in material remotion. The spacing arrangement 1.2 remain with many not worked areas between the scratches, needing rework to remove this material. The configuration with 0.8 was found a redundancy of work specially when used with the sense configuration of 1^st R-3^rd L-2^nd R.

Abstract: This paper reports a polishing disk which can substitute for rare earth. Using alumina - cerium oxide core-shell composite abrasive as abrasive, unsaturated resin as bonding agent, abrasive tool can be prepared by adding a water soluble pore-forming agent, suitable heat absorbing agent and active stuffing and the suitable addition amounts which are 25.6%, 46.8%, 18.5%, 3.8% and 1.2%, respectively .This abrasive tool can conduct the temperature in the grinding zone rapidly. It also has high grinding efficiency smooth polishing surface and without cracks or scratches, which meet furthermore, it has the merits of low cost and extensive use prospect. The polishing effect of rare earth polishing disk, but the low cost make it suitable for wide promotion.

Abstract: Plastic mold polished, in the mold cavity parting collapsed throwing angle appear, which seriously affect the dimensional accuracy and surface quality of the plastic parts, this article proposed two effective preventive measures: (1) cutting the model which having a same size as plastic model of the cavity at the parting surface, sticking the model and cavity parting with 502 glue together, within the required type of alignment, and then thrown together, polished finish will be a model to out; (2) in the plastic model cavity machining process, type in the mold cavity surface set aside allowance 0.5 ~ 1mm, polished until the cavity is completed, the surface of the cavity type 0.5 ~ 1mm rubbed off with a grinding allowance, it will ensure the cavity size and cavity to prevent the collapse of sub-surface angle at the phenomenon.

Abstract: In this study, the polishing machine’s mathematical model of the movement has been established by analysis the several polishing machines’ grinding and polishing process for tile. Then according to the model to simulate the trajectory and compare the grinding grain uniformity and the size of the grinding area. The results show that the disc grinding machine in improving of the efficiency of grinding and grinding grain uniformity is better than the other motions.