Papers by Keyword: Surface Roughness (SR)

Abstract: Chemical Mechanical Polishing(CMP) is currently the most effective planarization method used in the semiconductor industry. Because of the continuous improvement of the wafer size and line width, the CMP process must be promoted and improved. Many studies have been undertaken to try and achieve both a high material remval rate (MRR) while maintaing a high surface quality of silicon wafer, however up until this point it appears that the two objectives are mutually exclusive. In this paper, an innovative method which integrated ultrasonic vibration assisted machining and CMP (UCMP) has been developed. With the use of ultrasonic vibration, the CMP efficiency and the quality of ploished suface improves considerably as shown in this paper. The basic principle effects of ultrasonic vibration are further illustrated and the experiments had been done to demostrate the proper procedure. The results showed that UCMP achieves a higher material removal rate (MRR) and better surface quality at the same time.

Abstract: This paper focuses on experimental investigation on high speed grinding of 40 Cr steel with vitrified CBN grinding wheel, the effect of grinding process parameters, such as grinding speed, depth of cut, and feed rate, on the grinding force and surface roughness are analyzed The experimental results reveal that the grinding force decreases with higher grinding speed and increases with the addition of depth of cut or feed rate, and the surface roughness is satisfactory in high speed grinding.

Abstract: We compared the characteristics and polishing effect of abrasive suspension slurry jets with and without high polymer added. Results show that adding high polymer to the slurry jet leads to more concentrated jet beam and, consequently, surface roughness in the jet polished region is approximately equal and the interface between polished and unpolished regions is narrowed. We also examined the surface forming process polishing with slurry jet added with high polymer, and then proposed a polishing model of the process.

Abstract: Polishing is a manufacturing process for surface-smoothing. To minimize surface damage and defects, gentle polishing conditions are required. The main objective of this research is to determine the effect of polishing conditions by using Taguchi method , and to optimize the process parameters to obtain the best surface possible. The experimental results indicate that a set of optimal polishing conditions for producing work surface within the range of parameters evaluated, double oblique polishing path, relatively high speed and low feed rate are desirable for improve surface.

Abstract: The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of MQL under transient cutting speed before we go to the high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V by using PVD coated cemented carbide tools. The machinability of Ti-6Al-4V was investigated based on the effect on cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition. Completely dry machining and near dry (MQL) were applied in this experiment. For near dry machining, two levels of coolant flow rate were investigated, 50 and 100 mL/H. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more significant at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. No significant effect of the cutting speed and coolant flow rate on the surface roughness. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of application of MQL on cutting force at early stage of machining. MQL seems to be more affective when tools start worn out where greater contact area between tool and work piece occur to give better lubrication effect.

Abstract: Shot peening is a surface treatment that improves the performance of engineering components. In conventional shot peening, the medium consists of small spheres, which are usually made of high-carbon cast steel; the diameter of the spheres is in the range from 0.3 to 1.2mm. More recently, however, a new type of microshot has been developed to enhance the peening effect. The diameter of the spheres in the new medium is in the range from 0.02 to 0.15mm. In the present study, the effect of microshot peening on the surface characteristics of spring steel was investigated. The injection method of the microshot was of the compressed air type. The microshots of 0.1mm diameter were high-carbon cast steel and cemented carbide, and the workpiece used was the commercially spring steel JIS-SUP10. The surface roughness, hardness and compressive residual stress of the peened workpieces were measured. The surface layer of the workpieces was sufficiently deformed by microshot peening. A high hardness or residual stress was observed near the surface. The use of hard microshots such as cemented carbide was found to cause a significantly enhanced peening effect for spring steel.

Abstract: Rapid prototyping (RP) can fabricate complex 3D physical models without geometric limitations. The surface of the RP processed components is excessively rough (called stair-step effect) and depends on several parameters such as thickness of layer, position on the platform, etc. This paper presents several surface roughness models and results of experimental research.

Abstract: Problem of ball bearing and roller bearing noise generation is important in present technology level, and its solution stands in front for a new machine designer. New materials of bearings create new problems of bearing noise generation, so research of noise and vibration generation mechanism in necessary. Problem of lubrication gives significant influence to vibration and noise generation in bearings, so in common task of bearing work vibration is quite complex and requires experimental verification of theoretical ideas. This paper is intended to cover noise generation mechanism of ceramic bearings in comparison to steel ones and evaluate influence of bearing lubricant with different properties. There are presented design of experimental workbenches, experimental research procedure and results from research. Experimental results material is presented graphically and numerically. Finally, conclusion on problem and results of experimental research are made.

Abstract: According to the three-factor theory, the surface roughness of different wood-based environmental materials was evaluated using the surface roughness profiling instrument, and the underlying effective factors of the differences were analyzed. The psycho-physiological examination of the materials’ roughness on human psychology and physiology was also carried out. During the examination, physical roughness factors of the materials were treated as the independent variable, and the heart rate variability (HRV) and dynamic blood pressure (DBP) were chosen as the dependent variables. The sympathetic and parasympathetic activities of human autonomic nervous system as toughing material surface were investigated depending on the time domain analysis of HRV. The results showed that there exists a negative linear correlation between the physical roughness of materials and the human psycho-physiologic indexes. Overall, wood materials were proper to physiological stimulate of the body, they can’t cause the risk of physiological imbalance and would soon return to normal mentation after touching. Mental capacity with HRV of the body could illustrate the suitable tactile sense characteristics with the performance of the basic physical quantities of wood materials.

Abstract: Dental ceramics are attractive in restorative dentistry due to their approximations to the appearances and functions of human teeth with which we chew our food. Chewing processes generally occur at cyclic loading range of 70–800 N and up to 1400 cycles per day. Most fatigue studies on dental ceramics were conducted at the loads up to 250 N. These loads are much smaller than the maximum bite forces of 500–700 N and tooth clench or grinding forces of up to 800 N. This paper reports on an investigation of fatigue response of a dental porcelain at the higher end of the load range impacted by a tungsten carbide ball. The responses of surface roughness and contact stress to the applied loads and cyclic numbers were quantitatively studied. The results show that the cyclic numbers had significant influences on both average surface roughness Ra and maximum roughness Rmax (ANOVA, p<0.05). However, the applied loads did not significantly affect Ra and Rmax values (ANOVA, p>0.05). It is also found that the contact stress significantly reduced with the cycles (ANOVA, p<0.05) but did not show a significant change with the applied loads (ANOVA, p>0.05).