Papers by Keyword: Grind

Abstract: The impact of surface stress due to polish and grind processes on wafer bow was studied as a function of abrasive size. Results indicate that sub-surface damage from these processes can introduce significant surface stress. For polishing processes, this stress is proportional to mean abrasive size. The study also investigates stress as a function of depth below the wafer surface and finds that most stress is concentrated near the wafer surface.

Abstract: An investigation was undertaken to explore the grinding characteristics in grinding of yttrium vanadata (YVO4) crystal by using a resin diamond wheel. The grinding forces and surface roughness were measured and the morphological features of ground workpiece surfaces were examined. The results indicate that the depth of cut is the leading factor in affecting grinding forces whereas the surface roughness is mainly governed by the grinding speed. The material removal mechanism was found to be dominated by brittle fracture mode at conventional grinding speeds, and gradually transfer to ductile flow mode under higher grinding speeds, which is greatly related to the maximum undeformed chip thickness.

Abstract: Based on the carbide material characteristics of two low and three high and its process characteristics, analysis the carbide milling cutter is easy to form crack defects in the grinding process. Through a briefly introduce the milling mill grinding process, the cemented carbide milling cutter grinding cracks are produced by a variety of reasons are detailed researched; Based on the causes of crack of the carbide milling cutter, the feasible preventive measures are put forward. And these research results can significantly reduced the crack phenomenon in the process of milling cutter grinding in corresponding enterprises, and which is of great significance for reducing the production cost for enterprises.

Abstract: Fused zirconia alumina has been broadly applied in abrasive industry due to its excellent strength and toughness. The aim of the present work is to investigate the effect of t-ZrO₂ content on grinding performance of fused zirconia alumina. Commercial fused alumina zirconia (ZA25) powder was used to fabricate the particle size of 380-830 μm abrasive samples for grinding experiment by pressure granulation and sintering at different temperatures. Phase identification of abrasives sintered at different temperatures was made by X-ray diffractometry and the correlations between t-ZrO₂ content and grinding performance of abrasive were also tested. The results showed that t-ZrO₂ content of abrasive decreased with sintering temperature increasing within a range of sintering temperatures from 1375 °C to 1450 °C. Grinding performance of abrasive was enhanced as increasing t-ZrO₂ phase in abrasive. The better the toughness of abrasive powders, the less shape and size change of abrasive powders during grinding, this is the reason why the high t-ZrO₂ phase contained fused zirconia alumina abrasive exhibit high grinding performance.

Abstract: Pursuant to evaluations obtained at solving this topics in 2010, when was successfully supplied filler at acrylate coatings with grind cullet (waste glass), was chosen referential mixtures of silicate coatings with optimum quality. In Those choice mixtures was made a filler modification by various quantity of the cullet. Used cullet is from crushed glass bottle, that can’t be used for recyclation no more. Filler modification was provided so, to the new filler mixtures was approximate to ideal grading curve. The sieve analysis of original filler materials was made and after comparison of the results were proposed mixtures of new modified mixtures of filler. These then was further analysed and modified. The basic characteristic that was on modifying materials monitored belongs to cohesion with basis, consistence, vapour diffusion and smash strength. Considering absence of coatings surface quality classification Methodist in Czech prescriptions, was for the work needs created a personal methodology for classification coatings surface quality classification.

Abstract: Mechanical grinding method was employed in this study to disperse CaCO3 whiskers in cement matrix. Mechanical properties of the ground whisker reinforced cement were measured. It is shown that the mechanical grinding method was advantageous to the dispersion and mechanical properties of composites. But the grinding process must be proper to assure a certain length and integrality of the whiskers. Crack deflection and whisker pullout mechanisms could account for the strengthening and toughening effects caused by whiskers.

Abstract: In the process of grinding precision balls, the motion state of balls has an important influence on the efficiency and quality. However, the normal movement of balls will be damaged because of slipping, so it must be avoided. Besides, to process different materials of balls, it should use different processing parameters. This paper studies a numerical analysis on the kinematic characteristics of the motion of balls, analyzes processing parameters which impact the motion of balls during grinding and the difference of the motion state of bearing balls and resin balls. Study shows grinding pressure and plate speed have a great influence to the motion of balls during grinding.

Abstract: Large amounts of silicon dusts, including band saw dusts, grinding dusts and wire saw dusts were generated in photovoltaic industry. Recovery of pure silicon from the dusts is of great value to industry, and understanding their oxidation behaviors is essential for such recovery. The present paper reports our investigations into the oxidation status of the as-generated dusts and their oxidation kinetics in further exposure. Hand-ground multi-crystalline silicon fine powders from broken wafers were used as reference. And the oxidation behaviors of the reference silicon powders were also discussed. The results show that severe oxidation on the surface of the band saw and grinding dusts occurs due to the existence of the aqueous medium. With the storage time prolonged, the oxidation increases rapidly in the aqueous medium in the ambient temperature initially, and then it drives to stabilize. While no obvious oxidation appears in the wire saw dusts due to the protection of PEG (polyethylene glycol). With the PEG concentration in the liquid medium increased, the oxidation degrees of the multi-crystalline silicon fine powders are decreased. Based on above knowledge, an efficient suppression of oxidation of band saw and grinding dusts was proposed lastly.

Abstract: Activated cement with the characters of low water demand and high activity was made with Portland cement clinker and dehydrate-gypsum and liquid superplasticizer which were used as grinding additive in the grinding process. Three states of grinding effect exist with correspondence of different dosages of super-plasticizer: the optimal grinding aid dosage, the critical dosage, and the supercritical dosage. First, under the condition of the optimal grinding effect, the activated cement had the maximum strength with little dosage of super-plasticizer and small effect on the performance of activated cement; second, within the critical dosage, the strength of activated cement was similar to the common cement, more super-plasticizer were held and the performance of cement was obviously improved; third, within the supercritical dosage, the strength of activated cement was reduced, but it can accommodate much super-plasticizer, and had a remarkable influence on the performance of cement. The experiment also shows that different properties of low water demand activated cement can be made with admixture of different concentrations of super-plasticizer. Within the allowed limit, use more admixtures was in compile with green environmental protection concept, improve the durability of concrete, and resolve the problem of compatibility between common cement and super-plasticizer, and offered technical support in the produce of commercial concrete by directly use of Portland cement clinker.

Abstract: The grind-hardening of steel 65Mn had been carried out on a conventional surface grinder with alumina grinding wheel, the influence of depth of cut on the microstructure and the microhardness of workpiece, the depth and its uniformity of grind-hardened layer were studied. The results show that the completely hardened zone of grind-hardened layer is composed of fine acicular martensites, residual austenites and a little carbide. The variety of depth of cut has no obvious influence on the microstructure and the microhardness of completely hardened zone of grind-hardened layer. The maximum depth of grind-hardened layer and the depth uniformity of grind-hardened layer of workpiece increases with the increase of depth of cut a_p.