The Research on the Improved CMG Tool for Al2O3 Ceramic

2011 ◽  
Vol 121-126 ◽  
pp. 514-518
Author(s):  
Heng Zhen Dai ◽  
Zhu Ji Jin ◽  
Shang Gao ◽  
Zhan Chun Tao ◽  
Feng Wei Huo

A new D/SiO2 CMG tool for Al2O3 ceramic process was developed by adding some diamond abrasive into SiO2 CMG tool. The solid state reaction between the CMG tool and Al2O3 ceramic played a key role for achieving ultra-precision, high efficiency and low damage.Three kinds of formulations for the D/SiO2 tool were tested and evaluated. The material removal rate(MRR) of Al2O3 ceramic mainly depended on the content of diamond abrasive. In contrast with the corresponding SiO2 tool,the D/ SiO2 tool, which had minimal content of diamond abrasive,could achieve a minimal Ra and better MRR. The enhanced mechanical removal action made the MRR improve nearly twice times, and the process surface roughness of Al2O3 ceramic specimen using the D/ SiO2 tool kept almost same value as using the SiO2 tool without surface damage. Thus the D/ SiO2 tool is more suitable for process of Al2O3 ceramic workpieces.

1994 ◽  
Vol 116 (3) ◽  
pp. 423-429 ◽  
Author(s):  
J. C. Wang ◽  
S. M. Hsu

Ceramics are hard and brittle. Machining such materials is time-consuming, difficult, and expensive. Current machining technology requires stiff machine, high hardness tools, and small material removal rates to minimize surface damage. This study demonstrates the feasibility of a novel ceramic machining concept that utilizes chemical reactions at the tool-workpiece interface to reduce the stress and minimize the surface damage. A series of cutting tests using a diamond wheel on silicon nitride with different chemical compounds has been performed. The results demonstrate that by using different chemistries, the material removal rate and the surface finish of the machined ceramic can be significantly altered. Some halogenated hydrocarbons show a significant improvement over some commercial machining fluids currently in use.


2007 ◽  
Vol 329 ◽  
pp. 69-74
Author(s):  
H. Cheng ◽  
H.Y. Tam ◽  
Y. Gao ◽  
Yong Bo Wu ◽  
Y. Wang

This paper proposes a sub-aperture grinding tool for loose abrasive computer controlled surfacing, which is designed to perform epicyclic motion and rotate around its centre at a rapid rate, whilst the entire mechanism revolves around a secondary centre at a slower rate. In actual process, the wear of the tool could affect the material removal function, and make the process unstable, thus in fact, it is difficult to make a deterministic manufacturing. The focus of the present paper is on wearing characteristics of sub-aperture tools and the wear evenness as the main objectives. To make a further study, material removal function of the tool is firstly established through theoretically modelling, next, a correlative function with weighted factors is built, which is suitable for specifying the wearing degree of the tool. Finally, to discover the relationship between the material removal rate and the tool wearing characteristics, and to optimize the grinding process, analysis and experiments are then carried out on a K9 glass specimen by means of three kinds of tool materials, i.e., polyurethane pad, aluminum plate and pitch based on the proposed technique and model. The results indicated that the required high efficiency and precision could be achieved by choosing proper processes.


2009 ◽  
Vol 416 ◽  
pp. 439-442
Author(s):  
Xun Lv ◽  
Ju Long Yuan ◽  
Dong Hui Wen

Semi bonded abrasive lapping is an effective ultra-precision lapping method. It can obtain good surface quality of workpiece in short time. This paper focused on the differences of processing features by comparing semi bonded abrasive lapping and loose abrasive lapping in several groups processing parameters. The results showed that the surface roughness of workpiece in semi bonded abrasive lapping was far superior to that of loose abrasive lapping in same processing parameters. And the MRR (material removal rate) of semi bonded abrasive lapping was slightly lower than that of loose abrasive lapping. For these features of semi bonded abrasive, a new processing flow would also be proposed in this paper.


2006 ◽  
Vol 304-305 ◽  
pp. 8-13 ◽  
Author(s):  
T. Jin ◽  
D.J. Stephenson

Optical surface finish below Ra 10nm can be achieved on a ‘Tetraform C’ grinder of ultra-high stiffness, when grinding a low alloy steel with or without the help of ELID (electrolytic in process dressing). Surface roughness generation modelling has been carried out to predict thepossible surface roughness values. Efforts have been made to transfer the process knowledge to different grinding mode using a rigid 5-axis Edgetek CNC grinder. The effects of material removal rate and grit size and also that of spark out passes on the surface roughness generated have been investigated.


2015 ◽  
Vol 220-221 ◽  
pp. 743-748
Author(s):  
Justyna Molenda ◽  
Adam Charchalis

The high demands required today by manufacturing engineers for machine parts and tools necessitate very precise machining. The finishing processes are an important perspective to be considered today for meeting the goals like parallelism, tolerances, flatness, and smooth surface. These processes are high-precision abrasive processes used to generate surfaces of desired characteristic such as geometry, form, tolerances, surface integrity, and roughness characteristics. A leading importance in this perspective has the lapping process. It leads to a surface with low roughness and high precision. The topographical structure resulting from lapping is very advantageous in sliding joints, because of the high ability of lubricant retention, as well as in nonsliding joints because of the high load-carrying ability. Many materials can be lapped, including glass, ceramic, plastic, metals and their alloys, sintered materials, satellite, ferrite, copper, cast iron, steel, etc.This paper reports the observations of steel C45 elements lapping process results. Workpieces were rollers with diameter 17 mm and height 10 mm placed in the conditioning rings with use of workholdings. Samples were divided to three groups according to their Vicker’s hardness: 160, 440, and 650 HV. After grinding, lapping process was conducted. Experiments were carried out with an angular speed of the lapping plate set at 65 RPM, and lapping velocity was v = 49 m/min. The lapping pressure was provided by dead weights and during experiments executing p = 0.04 MPa. Samples were lapped during 10, 15 and 20 minutes. Abrasive slurry was composed of silicon carbide grains mixed with kerosene and machine oil. Abrasive grains size was F400/17.The material removal rate (MRR) and specimens surface characteristic are studied in the light of workpiece material hardness. Test results show that applied process parameters are the best for steel which hardness is 440 HV. In that case, the lowest values of Raparameter were obtained in conjunction with satisfactory values of material removal rate. It can be also seen, as could be predicted, that lapping time influenced on lapping results. MRR increases and surface roughness decreases with time. The worst lapping results were obtained for normalized steel (160HV). It can be the effect of surface damage, like scratching and grooving by harder abrasive grains.


2009 ◽  
Vol 416 ◽  
pp. 529-534 ◽  
Author(s):  
Ren Ke Kang ◽  
Shang Gao ◽  
Zhu Ji Jin ◽  
Dong Ming Guo

With the development of IC manufacturing technology, the machining precision and surface quality of silicon wafer are proposed much higher, but now the planarization techniques of silicon wafer using free abrasive and bonded abrasive have the disadvantage of poor profile accuracy, environmental pollution, deep damage layer, etc. A soft abrasive wheel combining chemical and medical effect was developed in this paper, it could get super smooth, low damage wafer surface by utilizing mechanical friction of abrasives and chemical reaction among abrasives, additives, silicon. A comparison experiment between #3000 soft abrasive wheel and #3000 diamond abrasive wheel was given to study on the grinding performance of soft abrasive wheel. The results showed that: wafer surface roughness ground by soft abrasive wheel was sub-nanometer and its sub-surface damage was only 0.01µm amorphous layer, which were much better than silicon wafer ground by diamond abrasive wheel, but material removal rate and grinding ratio of soft abrasive wheel were lower than diamond wheel. The wafer surface ground by soft abrasive wheel included Ce4+, Ce3+, Si4+, Ca2+ and Si, which indicated that the chemical reaction really occurred during grinding process.


2013 ◽  
Vol 797 ◽  
pp. 261-265 ◽  
Author(s):  
Jian Xiu Su ◽  
Zhu Qing Zhang ◽  
Jian Guo Yao ◽  
Li Jie Ma ◽  
Qi Gao Feng

In this paper, according to the slurry ingredients obtained by former research, the influences of the chemical mechanical polishing (CMP) process parameters, such as the rotational velocity of the platen and the carrier, the polishing pressure and the abrasive size on the material removal rate (MRR) and surface roughness Ra have been studied in CMP SiC crystal substrate (0001) C and (0001) Si surface based on the diamond abrasive. The research results show that the material removal rate changes with the change of the abrasive size, the rotational velocity of the platen and the polishing pressure significantly, but the maximum of MRR can be obtained at a certain rotational velocity of platen, abrasive size and polishing pressure. The influence of the abrasive size, the platen velocity, the carrier velocity and the polishing pressure on surface roughness is no significant. Under the same conditions, the MRR of CMP the Si surface is larger than that of the C surface. This study results will provide the reference for optimizing the process parameters and researching the material removal mechanism in CMP SiC crystal substrate.


2013 ◽  
Vol 770 ◽  
pp. 150-154 ◽  
Author(s):  
Zhen Wei Bai ◽  
Qiu Sheng Yan ◽  
Jia Bin Lu

As a new multifunctional material, strontium titanate (SrTiO3) ceramic has a wide application in grain boundary layer capacitor (GBLC) with the microstructure characteristics of semi-conductive crystalline grain and insulated boundary. An ultra-precision nanofishing technique is developed to lap and polish the brittle and thin SrTiO3 substrate with the cluster MR-effect plate where the abrasives are constrained by the cluster MR-effect chains, under the influence of a magnetic field, the carbonyl iron particles (CIPs) and non-magnetic abrasive particles remove material from the surface of workpiece being machined in this paper. Mahr XT20 roughmeter, Keyence VHX-600 and Olympus S4000 microscopes are used to investigate the characteristic of machined surface and the mechanism of material removal. An ultra-smooth planarization surface of SrTiO3 substrate with surface roughness Ra 3.8 nm (Mahr), RMS 0.973 nm (Veeco interferometer) is obtained under a high efficiency. It is found that the pore structures of the sintered substrate would weak the machinability of SrTiO3 and influence the further improvement of surface quality.


1962 ◽  
Vol 84 (4) ◽  
pp. 483-489 ◽  
Author(s):  
J. Frisch ◽  
R. R. Cole

The effects of electrolytic grinding on surface conditions and residual stress characteristics has been experimentally investigated. Surface finish, uniformity of material removal, and corrosion resistance are found to be dependent on mechanical removal rate as determined by wheel downfeed as well as electrolyte flow rate. Downfeeds of approximately 0.002 in. in the process do not produce measurable residual stresses and therefore it was further established that electrolytic grinding with moderate downfeeds can be used in place of swab etching techniques for evaluation of residual stress distributions. The maximum residual surface stresses were found to be not more than 22,000 psi, well below the yield strength of the material and were induced during the most severe grinding conditions.


2009 ◽  
Vol 76-78 ◽  
pp. 240-245
Author(s):  
Feng Jiao ◽  
Bo Zhao

Lower machining efficiency of traditional lapping with free abrasive restricts the enhancement of the precision parts’ production efficiency. It is necessary to improve lapping efficiency on the premise of guarantee of lapping quality. In this paper, a new ultrasonic aided lapping technology was developed by combining lapping technology and ultrasonic machining technology and a series of lapping experiments of ZTA engineering ceramic with and without ultrasonic assistance were carried out. The results of theoretical analysis and experimental study show that it is the ultrasonic assistance of the lapping tool that promotes the enhancement of lapping efficiency and the ultrasonic aided lapping technique with fixed abrasive can be regarded as a high efficiency processing method of the precision engineering ceramic part.


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