Mirror Surface Grinding Research Articles

Research on Metal Cement Grinding Wheel for ELID Precision Mirror Surface Grinding

Research on Metal Cement Grinding Wheel for ELID Precision Mirror Surface Grinding

Ultraprecision Machining. ELID-Grinding Technique Realizing Ultraprecision and Ultrafine Fabrication.

ELID grinding is a method that realizes high quality mirror surface grinding in the nanometer order by use of electrolytically dressing metal-bonded wheels consisting of fine abrasives. Currently, ELID grinding is increasingly being applied as an ultra-precision grinding method to achieve desired surface roughness, high surface accuracy, high surface quality, and high grinding performance. This paper introduces the principle of ELID grinding and discusses some applications of ELID grinding to mirror surface grinding.

813 ELID研削による脆性材料の薄片化の試み(ELID研削)(OS.1 生産加工・工作機械)

For the purpose of realizing the efficient and highly accurate machining, we proposed the simultaneous grinding method of different materials in ELID grinding. We are carrying out studies to grasp the basic feature of this grinding technique. In this study, the attempts on the mirror surface grinding of Si thin sheets using the simultaneous grinding method and fine diamond wheels were carried out and its grinding performance was investigated. Experimental results showed that mirror surface finishing to a thickness of 50μm could also be achieved using a #40000 diamond wheel. In this case, the obtained surface roughness was 14.5nm Ry. The experimental results confirmed that this method is use for obtaining thin sheets with mirror surface finishing.

Precision internal grinding with a metal-bonded diamond grinding wheel

A metal-bonded grinding wheel, compared with conventional grinding wheels, offers the advantage of high hardness, high holding ability and finer usable abrasive grit mesh sizes. The truing and dressing of a metal-bonded diamond (MBD) wheel, in practice, are very difficult. To grind small-diameter internal cylindrical surface with MBD-wheels, an interval electrolytic in-process dressing (ELID) method was utilized. Experiments were carried out on an ordinary cylindrical grinding machine with an attached internal grinding set-up, and straight type grinding wheels of different grit sizes were used. The grinding wheels were trued, using the electrical discharge method, and the effects of electrode shapes, grinding parameters, and grit sizes were evaluated experimentally. Mirror surface grinding of different materials was carried out with a #4000 CIB-D wheel, incorporated with this interval ELID (ELID II) method. The experimental results are reported.

Cylindrical grinding of bearing steel with electrolytic in-process dressing

Cylindrical surfaces are increasingly utilized in various areas, and related high-efficiency and high-quality fabricating technologies are of great importance and significant benefit to modern industry. To provide fundamental knowledge for the bearing industry, studies have been conducted on the use of cast-iron-bonded cubic boron nitride (cBN) superabrasive wheels, based on electrolytic in-process dressing (ELID) technique for realizing high-efficiency grinding of steel cylindrical workpieces. Therefore, in this investigation, experiments were carried out on an ordinary cylindrical grinder with a hydrodynamic spindle, and straight type grinding wheels of different grit sizes were used. The effects of grit sizes on surface roughness as well as waviness, roundness, and surface stress were evaluated in both the traverse and plunge grinding modes. Comparison of ELID grinding with other processes was also carried out. Mirror surface grinding of different materials was achieved with the #4000 CIB-cBN wheel. ELID grinding was confirmed to induce compressive stress and to be more cost effective for small batch production of larger components when it works in the traverse mode.

505 GSOの薄板のELID研削加工特性(機械工作・生産工学)

GSO is a material which is gradually being employed for the scintillators used in nuclear medical diagnoses such as PET and SPECT. However such characteristics as poor machinability and difficulty in achieving efficient quality machining have impeded the rapid increase in the use of GSO. In this study, the authors thus attempted the mirror surface grinding of GSO by the electrolytic in-process dressing (ELID) grinding method, which has been successfully used to obtain efficient and high quality ground surfaces of brittle materials. In the experiments, #400 to #8000 cast bonded diamond wheels were used to investigate the ELID grinding characteristics of GSO. The results of the experiments showed that 1) the ground surface roughness improves as the abrasive diameter becomes smaller, and a high quality grinding surface of 9.0 nmRy can be achieved with the #8000 wheel, 2) SEM observation confirmes that the removal mechanism by the #4000 wheel and above is mainly in the ductile mode, 3) Grinding of GSO by ELID was stable, and good surface could be achieved in the mirror-surface grinding of thin sheets using the #8000 wheel and ELID grinding.

508 金型自由曲面のELID鏡面研削(機械工作・生産工学)

508 金型自由曲面のELID鏡面研削(機械工作・生産工学)

Highly Efficient and Precision Fabrication of Cylindrical Parts from Hard Materials with the Application of ELID (Electrolytic In-Process Dressing)

The ELID (Electrolytic In-Process Dressing) grinding process, which incorporates in-process dressing of metal bonded superabrasive wheels, was applied for efficient and precision grinding of hard materials such as ceramic, hard metals, and quenched steels. Addressed in this paper are some of the typical applications of ELID Grinding for cylindrical machining. The significant advantages, performances, and characteristics of mirror surface grinding for external surface, internal surface, and end-face Finish processes of cylindrical components are described.

A Study on the Monitoring of Grinding Stability Using AE Sensor in Electrolytic In-Process Dressing Grinding

Electrolytic in-process dressing grinding technique which enables application of metal bond wheels with fine superabrasives in mirror surface grinding operations has developed. It is possible to make efficient precision machining of hard and brittle material such as ceramic and hard metal by the employment of this technique. However, in order to ensure the success of performances such as efficient machining, surface finish, and surface quality, it is important to sustain the insulating layer that has sharply exposed abrasives in wheel surface. Using AE(Acoustic Emission) sensor, this paper will show whether the insulating layer sustains stably or not in real grinding time. And by comparing AErms value and surface roughness their thresholds for stable electrolytic in-process dressing grinding will be determined.

Damping improvement of machine tool columns with polymer matrix fiber composite material

In order to improve the damping capacity of the column of a percision mirror surface grinding machine tool, a hybrid column was manufactured by adhesively bonding glass fiber reinforced epoxy composite plates to a cast iron column. To optimize the damping capacity of the hybrid column, the damping capacity of the hybrid column was calculated with respect to the fiber orientation and thickness of the composite laminate plate and compared to the measured damping capacity. From experiments, it was found that the damping capacity of the hybrid column was 35% higher than that of the cast iron column.

Design and manufacture of a three-axis ultra-precision CNC grinding machine

A three-axis CNC grinding machine tool for the ultra-precision mirror surface grinding of advanced materials such as ceramics and other hard and brittle materials has been designed. The grinding machine is composed of the air spindle, a high-damping resin concrete bed, and a three-axis CNC controller with high resolution AC servo motors. For the stiffness calculations of the grinding machine, a new modeling method for linear motion guides and ball screws using the three dimensional finite-element method was introduced. From comparison of the calculated results with the experimental results, it was found that the modeling method gives accurate results in the prediction of the stiffness of machine tools. Based on the results, a prototype three-axis CNC grinding machine was designed and manufactured. To investigate the dynamic properties of the grinding machine, the natural frequencies and damping of the spindle and the headstock were measured experimentally. Also, the mode shape of the machine tool x-table at the first natural frequency was obtained experimentally. From the grinding operation of ceramic materials, it was found that the prototype grinding machine tool produced mirror surfaces on aluminum oxide and titanium carbide, with arithmetic surface roughnesses of less than 50 nm.

Mirror surface grinding of ceramics using a three-axis precision cnc grinding machine

In this paper, the mirror surface grinding of ceramics, such as Si 3N 4 and Al 2O 3TiC, was realized with average roughness less than 10 nanometers. For the grinding operation, a three-axis CNC grinding machine tool was designed and manufactured. The grinding machine is composed of an air spindle, a high damping resin concrete bed and a three-axis CNC controller with high resolution AC servo motors. The dynamic properties of the grinding machine, such as the natural frequencies and damping of the spindle, were experimentally measured to improve the ground surface quality. Also, the truing method to improve the straightness of the grinding wheel with 1 μm accuracy, was developed.

Mirror surface grinding characteristics and mechanism of carbon fiber reinforced plastics

In this work, the mirror-surface grinding of carbon-fiber reinforced plastics(CFRP) was realized using a micro grain metal bonded diamond wheel with electrolytic in-process dressing (ELID). The surface roughnesses R max of the CFRP that were obtained with a # 6,000 wheel were up to 0.65 μm, and thus were rougher surface finishs compared to those of hard and brittle materials ground with the same mesh number wheel with ELID. The grinding performance was much dependent on the grinding direction and the best surface roughness was obtained when at 90° grinding with the fiber direction. The spark-out effect on the surface improvement was significant when mirror surface grinding was performed. From surface observations of the CFRP with a scanning electron microscope (SEM) and Auger electron spectroscopy (AES), it was found that the mirror surface grinding of CFRP was generated by the homogenization due to carbonization of the ground surface and smearing of chips composed of the carbon fiber and carbonized epoxy resin into the ground surface.

Analysis of Mirror Surface Generation of Hard and Brittle Materials by ELID (Electronic In-Process Dressing) Grinding with Superfine Grain Metallic Bond Wheels

Mirror surface grinding operations were conducted by using ultrafine grain metallic bond wheels with electrolytic in-process dressing(ELID). Workpieces of hard and brittle materials, such as monocrystalline silicon, glass, and ceramic, were ground. Wheel abrasive grains used mainly were diamond of several microns down to submicrons. Ground surface roughness versus grit size was shown. SEM and AFM were adapted to analyze ground mirror surface generation, and surface topographies due to grit size were compared. Subsurface damage was evaluated through X-ray, angle-polish and step-etching. High surface accuracy, good surface finish, and low subsurface damage were all successfully achieved. The advantage of a constant in-feed pressure in ultrafine grinding was shown, and Ra of several angstroms was achieved.

Mirror surface grinding for brittle materials with in-process electrolytic dressing

Use of a diamond wheel with superabrasive is required for mirror-like surface grinding of brittle materials. However, conventional dressing methods cannot apply to the diamond wheel with superabrasive. Recently, an electrolytic dressing method was developed for use with a cast iron-bonded diamond wheel and superabrasive. This technique can replace lapping and polishing. Using electrolytic dressing, surface roughness of the workpiece was improved significantly, and the grinding force was very low and the continuity of the grinding force was also improved. The purpose of this study was to achieve mirror-like surface grinding of ferrite with electrolytic dressing of a metal-bonded diamond wheel. For application of ultraprecision grinding for brittle material, superabrasive, air spindle, and in-process electrolytic dressings were used. Additionally, the effects of pick current and pulse width on ground surface were investigated, and suitable dressing conditions for ferrite were determined.

Mirror Surface Grinding of Silicon Wafers with Electrolytic In-Process Dressing

Summary The authors have studied finish grinding techniques, and succeeded In developing a new grinding technique that realises mirror quality surfaces. This new technique uses Electrolytic In-process Dressing and micro-grain cast iron fiber bonded wheel's. This enables stable mirror surfaces to be ground on conventional grinding or cutting machines. The technique has started to take the place of lapping and polishing. This paper describes the characteristics of the new grinding technique and Its features, and also the advantages as applied to mirror surface grinding of silicon wafer's.