Papers by Keyword: Roundness

Abstract: Injection molding is one of the most extensively employed manufacturing methods to produce high quality part at high production rate. However, achieving high precision and quality product is still one of the biggest challenges in injection molding process. In this study, the optimal value of injection molding parameters is investigated. The initial injection parameters are determined using Moldflow software, then it is tested in experimental setup with feedstock composition of 90% Cu and 10% PA-6. After the experiments are done, the optimal combined response can be calculated Taguchi-grey-fuzzy method. Furthermore, ANOVA is done to measure how much contribution is given by each of parameters. From the analysis, it is given that 10 MPa and 9 MPa is the optimal value of both injection pressure and holding pressure respectively. It is also noted that the holding pressure had a higher contribution (39.62%) than injection pressure (13.13%) on the dimensional change and roundness.

Abstract: Improving roundness of a local silica sand was conducted by abrasion using a laboratory ball mill having a diameter of about 156 mm with steel milling balls of 2800 g. Abrasion was conducted at a fixed speed of 30 rpm; with various sand loadings of 150, 200, and 250 g; and milling time of 60, 105, and 120 min. Roundness was evaluated based on Wadell equation and topography of particle surface was measured by using a new practical method consisting of a build-in camera in mobile phone and common image processing application. Results of measurement using this new proposed method had been confirmed with roundness reported from two service laboratories. The abrasion could increase the roundness of Sidrap sand from 0.20 to an average of 0.31, while the measured roundness of Ottawa standard sand was about 0.46. Three types of mortar were prepared from Sidrap sands before and after abrasion, as well as Ottawa sand. Compressive strengths of mortar after aging of 28 days were 345, 375, and 333 MPa respectively.

Abstract: In this study, mainly researching the improvement of roundness of thick SUS304 stainless steel tube by interior magnetic abrasive finishing using a magnetic machining jig. The influence of reciprocating velocity of magnetic pole unit on the improvement of roundness of interior surface was studied by establishing the dynamic equation of magnetic machining jig. Experimental results showed that low reciprocating velocity of magnetic pole unit is conducive to the improvement of interior roundness of the thick SUS304 stainless steel tube. The reason is that the low reciprocating velocity of magnetic pole unit reduces the pitch of the helical motion and can produce greater finishing force of the magnetic machining jig.

Abstract: This paper focuses on how bending and springback process of the titanium tubes with different bending radius and bending angle affect the springback rate after unloading and analyses tube distributions and variations of stress and strain by establishing a three-dimensional elastic-plastic finite element model of square TA18 titanium alloy tube based on ABAQUS/explicit and ABAQUS/standard. It is shown that under the same process parameters, the sprignback rate obtained by numerical simulation is in good agreement with that measured in the experiments. The springback rate after unloading increases with the increase of the bending radius linearly, and it increases nonlinearly with the decrease of bending angle. The distribution of the tube-roundness and the relationship between its roundness and springback rate under different process parameters could be obtained by comparing the variation of the absolute value of its outer wall unit at the maximum principal strain before and after unloading.

Abstract: This study described the effect of mechanical properties on the roundness of a drilled hole in the drilling of low-rigidity workpieces. A thin-thickness part workpiece model involving a beam plate structure fixed on both ends was used in the study. The effects of feed, workpiece length, distance from the fixed end to the drilling point, and mechanical properties of the workpiece on the roundness of the hole were investigated. The thrust force increased with feed and the roundness became worse with feed. The hole was enlarged in the longitudinal direction of the workpiece at the upper section of the hole. An increase in the workpiece length decreased the rigidity of the workpiece and deteriorated the roundness of the hole. The roundness error was extremely small when the drilling point was near the fixed end. Carbon steel, aluminum alloy, stainless steel, and titanium alloy were used as workpiece materials. The thrust force in the drilling of titanium alloy and stainless steel was considerably larger than that of the carbon steel and aluminum alloy. The roundness of the hole was worse in the drilling of titanium alloy and stainless steel than that in the drilling of carbon steel and aluminum alloy. Plastic deformation occurred in the workpieces made of titanium alloy and stainless steel, which is probably because the workpiece was yielded by the large thrust force. The value of the ratio of the thrust force in drilling to the Young’s modulus of the workpiece was used in evaluating the deflection of the workpiece and the roundness error of the hole in drilling.

Abstract: It was difficult to prepare micro-hole with large aspect ratio by traditional processing technologies. In order to solve the problem, a preparation was proposed. It was carried out by casting method. Carbon fiber and metal wire coated graphite paint were used as hole core respectively. And morphology and geometrical characteristic of micro-hole were observed and analyzed by scanning electron microscope and laser scanning confocal microscope. The results showed that average diameter and aspect ratio of micro-hole obtained by the group of carbon fiber hole core were about 0.2 mm and above 1700, respectively. For the other group, about 0.5 mm and 700, respectively. The micro-hole obtained by the metal wire coated graphite paint hole core was more close to circle. Its shape factor was about 0.72. The roughness of micro-hole value obtained by carbon fiber hole core was close to 3.2 μm, smaller than that of the metal wire coated graphite paint.

Abstract: Accurate and strong fastener assembly depends on precision of the hole. For structural material likes composites, these criteria is very important. Drilling is the most common method in producing hole on composites. But the main problem of drilling is excessive tool wear that may affect the quality of the holes. Punching is another alternative in making a hole. The main objective of this study is to compare between drilling and punching in terms of hole quality. The scanned images of the produced hole will be captured using commercial 3D optical surface measurement method namely Alicona IFM. The effect to the quality of the produced hole will be measured and compared between drilling and punching.

Abstract: Cylindrical parts with a protrusion are expected to be used in the components of consumer electronics and automotive products. The machining efficiency of these parts is very low, making them difficult to be mass-produced. The aim of our present work is to develop a highly accurate and highly efficient grinding process for a cylindrical surface with a protrusion. This paper describes the results of experiments using a straight cup-shaped grinding wheel. The following conclusions can be drawn. (1) To prevent uneven wear of the grinding wheel, an oscillation operation is necessary during the grinding process. (2) By employing the straight cup-shaped grinding wheel, the grinding process is realized with the aim of achieving the following: high machining accuracy, roundness below 3 μm, straightness below 2 μm, and surface roughness below 2 μmRzjis.

Abstract: Particle shape raises more interest among geologists than among engineering geotechnical staff. It is commonly accepted that particle shape is the result of geological processes, such as transportation and sedimentation, and depends on many factors, such as mineral composition or structure and texture of the host rock. The influence of particle shape on the geotechnical properties of soil has been widely discussed in literature from the early 1900-ties, e.g. by Wadell [3], Riley [16], Pentland [6] and other scientists, who proposed their own definitions and methods of determining particle roundness and angularity. Finally, it has been decided that particle shape should be defined by three independent parameters [2]: roundness, reflecting the general shape of the particle in comparison to a sphere; angularity, describing changes in roundness in the corners of the studied particle; and microtexture, reflecting the complexity of the particle surface in micro scale; this parameter is also referred to as micromorphology. These three parameters describe particle shape at various magnifications and allow obtaining all important data on this feature. This report is focused on a review and analysis of the analytical methods determining particle angularity, and is an attempt to establish an optimal definition of determining particle angularity in road aggregates. We present selected definitions used to determine angularity, worked out by different authors over the years as an attempt to find the best analytical method of describing angularity.

Abstract: The roundness is one of the most important criteria to accept the mechanical parts in the CNC turning process. The relations of the roundness, the cutting conditions and the cutting forces in CNC turning is hence studied in this research. The dynamometer is installed on the turret of the CNC turning machine to measure the in-process cutting force signals. The cutting parameters are investigated to analyze the effects of them on the roundness which are the cutting speed, the feed rate, the depth of cut, the tool nose radius and the rake angle. The experimentally obtained results showed that the better roundness is obtained with an increase in cutting speed, tool nose radius and rake angle. The relation between the cutting parameters and the roundness can be explained by the in-process cutting forces. It is understood that the roundness can be monitored by using the in-process cutting forces.