Papers by Keyword: Green Machining

Abstract: Stainless steel 304 is one of the most promising materials for many industrial applications. Its machinability is poor whether machined in any environment. Conventional machining causes environmental degradation as well. In this paper, sustainable machining of SS304 using green lubricant is presented. Experiments have been conducted on Taguchi’s robust design of experiment technique. For machinability enhancement, a hybrid optimization technique VIKOR-Regression-PSO is employed. Machinability indicators that have been considered are tool wear, surface roughness, and chip reduction coefficient. Cutting speed, depth of cut, and feed rate have been considered as the variable machining parameters in this work. The hybrid optimization has been found very effective and provided a set of optimum machining parameters i.e. cutting speed-70m/min; feed rate-0.1mm/rev; depth of cut-0.5mm for the best values of machinability indicators i.e. tool wear-249.22 μm, roughness-11.08 μm, chip reduction coefficient-2.26.

Abstract: In this paper, experiments are conducted on drilling AISI 316L Austenitic Stainless Steel material using minimum quantity lubrication technique under formulated environmental friendly Pongam oil as cutting fluid. Cutting torque, Thrust force and Surface roughness and Chip formation are studied for the evaluation. The experimental results show that, the Cutting torque is dropped by 36 % under modified Pongam oil as cutting oil, compared to mineral oil base cutting fluid. About 34 % drop in Thrust force and Surface roughness values are noticed under formulated Pongam oil. Further, spiral and continuous form chips are seen under vegetable oil mode of lubrication compared discontinues spiral form under mineral oil based cutting fluid.

Abstract: Ceramic balls are great application in high precision components such as hybrid bearings or hip prostheses where high performance is only achieved through close tolerances of form and dimension. Green machining is a critical step in the manufacturing of balls since the allowance removed and the surface finish achieved at the conclusion have a direct influence on the quality of the final product. The work aims to design a prototype for machining the green ball to Ø19 mm following the approach of mechanical design methodology. The concept consists of three wheels, two for drag with speed and direction of rotation variables to promote random orbital effect on the ball and a grinding wheel with track of silicon carbide #120 mesh. Spherical zirconia blanks were shaped by isostatic pressing at 200 MPa and machined in the manufactured prototype.

Abstract: The paper gives a short review of P/M routes which were developed or adapted by the authors for the net-shape manufacturing of titanium implants. Special attention is paid to the production of highly porous bone implants, where the porosity is achieved by the application of temporary space holder particles, which are removed before or during sintering by decomposition or dissolution. In this case, shaping was done either by machining of powder compacts in the green and sintered state or by metal injection moulding (MIM). The challenges of these shaping technologies and current solutions are discussed. To complete the review, two promising new technologies for the net-shape production of highly porous titanium implants, the replica technique and additive manufacturing are briefly introduced.

Abstract: In the last years there has been an increased demand to lower the impact of industrial activities on environment quality. Cutting fluids, among other products, are an important pollutant but they have often been associated with the need for a higher productivity of machining processes. Cutting fluids are a mean of reducing temperature in the cutting area, friction and tool wear but they also represent 7% to 17% of the production costs. Other problems raised by cutting fluids are: microorganism infestation, which can cause pulmonary and dermatological diseases and poor lubrication or corrosion caused by some of the chemicals. Dry cutting is regarded as the cleanest cooling method, but it has a reduced heat dissipation efficiency and practically there is no lubrication. Other relatively new green solutions concern the use of minimum quantity lubrication (MQL) and cryogenic machining.

Abstract: Dry machining has been successfully used in several machining applications with different cutting tools and workpiece materials due to its environmental friendliness. Dry hard turning has become an alternative machining process to grinding due to its ability to increase material removal rate, reduce production costs, and enhance of material properties. However, hard turning has several issues such as high temperatures at the tool-chip and tool-workpiece interfaces which are affecting negatively on the surface integrity of the machined parts. Using conventional cutting fluids can improve machining performance by reducing the temperature in the cutting area. However, conventional cutting fluids have some issues such as pollution, hazard on operator, high cost, and corrosion for machine tool and workpiece. All these issues related to applications of conventional cutting fluids have encouraged the researchers to look up for another alternative cooling technique in machining operation. Cooling gas has been explored as one of the alternative cooling techniques. The present paper studies the effect of applying nitrogen gas on surface roughness and tool life under different cutting parameters (cutting speed of 100, 135, and 170 m/min, feed of 0.16, 0.2, and 0.24 mm/rev, with constant depth of cut of 0.2 mm) for hard turning of stainless steel (hardness of 48 HRC) using coated carbide tools. Results showed that better surface finish and longer tool life were achieved by using nitrogen gas coolant condition compared to dry cutting.

Abstract: The machinability of Titanium alloy Ti6Al4V is poor, so the new green cutting technology with water vapor and ionized air as coolants and lubricants was proposed to achieve the aim of efficient and green cutting for Ti6Al4V. In this paper, the milling formation and milling force were studied in machining Ti6Al4V with application of ionized air and water vapor for cooling lubricants. A set of milling tests using carbide tool YG6 were performed under dry cutting, oil emulsion, water vapor and ionized air, respectively. The results of tests indicated that the milling formation was decreased with increasing feed per tooth and the milling force increased with increasing feed per tooth, the milling formation and milling force were reduced during water vapor and ionized air condition.

Abstract: Conventional coolant/lubricants have some drawbacks such as high cost, pollution, and unsatisfactory product quality. New cooling approach by using gases to enhance machinability has been investigated. This study presents the finding of nitrogen gas and nitrogen-oil-mist as conditions when turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Turning experiments were carried out on CNC turning machine using rhomboid type wiper coated carbide cutting inserts. The result show that better product surface finish and longer tool life, as well as decrease cutting temperatures could be achieved by using nitrogen-oil-mist condition compared to nitrogen gas condition.

Abstract: This papers studies the use of robots in the green machining of ceramics, specifically, the machining of high alumina porcelain insulators. The green state has very low strength and high brittleness where the forces applied during machining can generate and/or develop defects in the part that will reduce their properties after sintering. This work aims to study the machining by robot models of electrical insulators in 1:10 scale. Blanks were compacted in high alumina porcelain by isostatic pressing and green machined with a manual grinder attached to a Kuka KR16 robot. Models of insulators in gypsum were successfully machined and used for setup and configuration of the process. They were machined with cutting depth 0.87 mm and feed of 20 mm/s, this is the minimum programmable velocity for this robot model, and these parameters for the machining of the green porcelain generated excessive cracks at the tips of the fins. Changing the cutting depth to values of 0.25 mm, an established value in CNC machining, allowed to conclude that insufficient stiffness of the robot together with its high forward speed and excessive vibration of the grinding limits its use for thin thicknesses, although with potential for improvement.

Abstract: In the process of cutting, the problem of flying chips seriously affect the processor’s life safety and the processing environment of workshop. In order to study the characteristics of the chips flying, the authors selected five different kinds of commonly used milling insert, and use these milling insert in the dry milling experiments to study the process of cutting chips flying. In the paper, firstly, carried out flying track analysis on the chips, and concluded the chips flying theory, and then design the cutting experiment, through the statistical analysis of experiments data, to understand the influence of different insert groove chip and cutting parameters to chip flying, and puts forward suggestions on groove development of heavy-duty cutting inserts.