Experimental studies using minimum quantity cooling (MQC) with molybdenum disulfide and graphite-based microfluids in grinding of Inconel® alloy 718

In the paper, the results of experimental studies related with determination of the influence of the supply of a grinding fluid (GF) doped with powdered graphite and MoS2 into the machining zone with the minimum quantity cooling (MQC) method on the course and results of the reciprocating internal cylindrical grinding of rings made from Inconel® alloy 718 have been presented. As a grinding fluid, water aerosols were used. The aerosols delivered the following into the grinding zone: water slurry MoS2 with a concentration of 30 g/dm3, water slurry of graphite with a concentration of 30 g/dm3, 5% water solution of Syntilo RHS oil and pure demineralized water. The obtained results of carried out experiments showed that the most favorable conditions of grinding wheel operation were obtained when MQC-based delivering an aerosol of water slurry made from demineralized water doped with MoS2 and graphite with a minimum flow rate and when delivering an aerosol of 5% water slurry of Syntilo RHS oil. It was proved that doping GF with powdered MoS2 and graphite, with delivery in the form of an aerosol with a minimum flow rate, has a substantial influence on the intensity of clogging grinding wheel active surface (GWAS). Additionally, it has been demonstrated that the solid grease MoS2 and graphite particles reached the area of contact of the GWAS and the machined surface effectively, actively influencing its tribological conditions of the grinding process.Web of Science1011-466163

Requirements specification and verification of production tooling

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1995.Includes bibliographical references (p. 125-127).by Roland J. Ayala.M.S

Development and Evaluation of a Novel Supply System to Reduce Cutting Fluid Consumption and Improve Machining Performance

Reducing cutting fluid consumption remains a goal of the machining industry. Despite their reported advantages such as heat dissipation, friction reduction, extended tool life, and improved surface quality, cutting fluids pose several health and environmental concerns throughout their lifecycle, in particular when conventional mineral oil-based, semi-synthetic or synthetic fluids are used. Manufacturers are encouraged to reduce the use of harmful conventional fluids. However, the usage of cutting fluid is still an unavoidable industrial practice, especially when machining titanium alloys, due to the generation of large quantities of heat. High cutting temperature is one of the main reasons for rapid tool wear and hence the poor machinability of titanium alloys. Vegetable oil (VO)-based fluids have been suggested as favourable alternatives to the conventional fluids due to their superior tribological properties and high biodegradability. Several cutting fluid supply systems have been developed to reduce cutting fluid use, such as minimum quality lubricant (MQL) and cryogenic cooling or to control the temperature in the cutting zone, for example flood, and high pressure cooling (HPC) systems, to improve productivity and increase the overall performance of machining processes. Even though process improvements are achieved by these systems, inaccuracies in estimating cutting fluid flow rates, high fluid consumption and low penetrability, as well as high set-up costs, are their technical and economic drawbacks. For these reasons, the need for an innovative supply system to deliver fluids in machining processes has become crucial. In this PhD project, a novel controlled cutting fluid impinging supply system known as ‘CUT-LIST’ is developed to deliver an accurate quantity of cutting fluid into machining zones through precisely-oriented coherent nozzles. The design of CUT-LIST is supported by numerous fluid dynamic and metal cutting theories along with extensive experimentation. The performance of the new system is evaluated against a conventional flood system during the step shoulder milling of Ti-6Al-4V using a water-miscible vegetable oil-based cutting fluid. The effect of cutting conditions on the key measures of the process are investigated, including cutting force, workpiece temperature, tool flank wear, burr formation and average surface roughness (Ra). The effect of CUT-LIST on the micro-hardness and microstructure of the machined surface as well as chip formation are also evaluated. The study shows that the new system provides a dramatic decrease in cutting fluid consumption of up to 42% with noticeable reductions in cutting force, tool flank wear and burr height of 16.41%, 46.77% and 60% respectively. Relatively smaller surface roughness (Ra) values are also found with the use of the CUT-LIST supply system. In terms of the effect of the new system parameters on key process measures, feed rate has a major effect on cutting force, burr formation and surface roughness, with the highest percentage contribution ratios (PCRs) of 47.46%, 38.69% and 39.10% respectively. Meanwhile, the cutting speed has a major effect on workpiece temperature and flank wear, with the highest PCRs of 46.5% and 59.23% respectively. Nozzle position at a 15˚ angle in the feed direction and 45˚or 60˚ against feed direction helped in minimising workpiece temperature. An impinging distance of 55 or 75 mm is also necessary to control burr formation, workpiece temperature, and Ra. Metallurgical observation shows that both systems achieved acceptable micro-hardness values for aerospace components (386.3 to 419 HV100). However, a slight reduction in micro-hardness of ~5.5% was recorded with the use of CUT-LIST. The hardness is lower at distances < 50 μm below the machined surface as a result of thermal softening, while it becomes higher at distances <100 μm from the surface due to cyclic internal work hardening. The micro-hardness then gradually decreases until it reaches the base material’s nominal hardness. Both systems also produce a thin, plastically deformed layer below the machined surface under all conditions investigated. Despite the noticeable reduction in cutting fluid consumption achieved by CUT-LIST, no significant disparity is found in the microstructural subsurface damage caused by the two systems. Microstructural alteration is strongly affected by cutting speed and fluid flow rate. At higher cutting speeds, the conventional system shows visible surface defects such as smearing, surface cavities and erosion in workpiece material. With both systems, desirable discontinued serrated chips are generated. However, the increase in fluid flow rate significantly influences chip morphology, while the average distance between chip segments is more pronounced and evident with the increase in cutting speed. Severe crack propagation (up to a depth of 200 μm) is observed in the chip end free surface, with the use of the conventional system. In addition, CUT-LIST shows decreases of up to 12.5 % in saw-tooth height (hmax) and increased segment width up to 13.63 % at higher speeds, while the transition from aperiodic to periodic serrated chip formation is closely controlled by cutting speed and feed rate. Chip segmentation frequency and shear angle are also found to be sensitive to cutting speed, whilst CUT-LIST provides a larger shear angle compared to the conventional system. Based on the results achieved by CUT-LIST, it is apparent that the new system possesses various advantages over the conventional system. Hence, CUT-LIST can be considered as a feasible, efficient, and ecologically beneficial solution, offering less fluid consumption in machining processes

Glosarium Peternakan

197 hal.;21 c

Welfare of pigs on farm

This scientific opinion focuses on the welfare of pigs on farm, and is based on literature and expert opinion. All pig categories were assessed: gilts and dry sows, farrowing and lactating sows, suckling piglets, weaners, rearing pigs and boars. The most relevant husbandry systems used in Europe are described. For each system, highly relevant welfare consequences were identified, as well as related animal-based measures (ABMs), and hazards leading to the welfare consequences. Moreover, measures to prevent or correct the hazards and/or mitigate the welfare consequences are recommended. Recommendations are also provided on quantitative or qualitative criteria to answer specific questions on the welfare of pigs related to tail biting and related to the European Citizen's Initiative ‘End the Cage Age’. For example, the AHAW Panel recommends how to mitigate group stress when dry sows and gilts are grouped immediately after weaning or in early pregnancy. Results of a comparative qualitative assessment suggested that long-stemmed or long-cut straw, hay or haylage is the most suitable material for nest-building. A period of time will be needed for staff and animals to adapt to housing lactating sows and their piglets in farrowing pens (as opposed to crates) before achieving stable welfare outcomes. The panel recommends a minimum available space to the lactating sow to ensure piglet welfare (measured by live-born piglet mortality). Among the main risk factors for tail biting are space allowance, types of flooring, air quality, health status and diet composition, while weaning age was not associated directly with tail biting in later life. The relationship between the availability of space and growth rate, lying behaviour and tail biting in rearing pigs is quantified and presented. Finally, the panel suggests a set of ABMs to use at slaughter for monitoring on-farm welfare of cull sows and rearing pigs.info:eu-repo/semantics/publishedVersio