Experimental Research Using of MQL in Metal Cutting

In this paper an effect of using of minimal quantity lubrication (MQL) technique in turning operations is presented. Experimental research was performed on carbon steel C45E. Technological parameters: depth of cut, feed rate and cutting speed were adjusted to semi-machining and roughing. Higher values ​​of feed and cutting speed were used, than recommended from literature and different types of cooling and lubrication in turning conditions were applied. As a conventional procedure and technology, lubrication with flooding was applied. As special lubrication the MQL technique was used. During research, monitoring of the cutting force, chip shape, tool wear and surface roughness was performed. Relations between parameters, material machinability and economy of process were analyzed

A comparative analysis of milling strategies of complex geometry surfaces

This paper analyses the influence of machining strategies and cutting parameters on the milling of aluminium complex geometry parts. In the first experimental phase, parts were machined with a combination of two roughing strategies and three finishing strategies, with recommended machining parameters. The machining time, machining surface roughness, and the surface geometric accuracy were measured. In the second phase, a new sample was machined with corrected cutting parameters using the best strategy adopted from the first phase. The results have shown that the selection of machining strategy and cutting parameters significantly affects the productivity, quality, and accuracy when machining complex geometry parts

Possibilities of Application of High Pressure Jet Assisted Machining in Hard Turning with Carbide Tools

High Pressure Jet Assisted Machining (HPJAM) in turning is a hybrid machining method in which a high pressure jet of cooling and lubrication fluid, under high pressure (50 MPa), leads to the zone between the cutting tool edge and workpiece. An experimental study was performed to investigate the capabilities of conventional and high pressure cooling (HPC) in the turning of hard-to-machine materials: hard-chromed and surface hardened steel Ck45 (58 HRc) and hardened bearing steel 100Cr6 (62 HRc). Machining experiments were performed using coated carbide tools and highly cutting speed. Experimental measurements were performed for different input process parameters. The cooling capabilities are compared by monitoring of tool wear, tool life, cooling efficiency, and surface roughness. Connection between the tool wear and surface roughness is established. Experimental research show that the hard turning with carbide cutting tools and HP supply CLF provides numerous advantages from the techno-economic aspect: greater productivity, reduce of temperature in the cutting zone, improved control chip formation, extended tool life, low intensity of tool wear, surface roughness in acceptable limits, significant reduce of production costs related to the CLF

Influence of Workpiece Hardness on Tool Wear in Profile Micro-milling of Hardened Tool Steel

Machining of engineering metallic materials on micro-level is very complicated. Micro-milling with solid tools, as one of microengineering technologies, is an acceptable process to machining of complex metallic micro-parts. The main problem in micro-milling is sensitivity of cutting tool, due its suppleness and short tool life, and its influences to workpiece accuracy and quality. In this paper is experimentally investigated tool wear of micro-milling tool. During machining tests, influence of workpiece hardness and process parameters is evaluated. Workpiece was cold work alloyed tool steel X155CrVMo12, hardened to different hardness 45, 54 and 63 HRc. Cutting tool was carbide ball-end micro-mill with TiAlN coating, and diameter of 0.6 mm. For different combination of input parameters, tool wear curves is presented, and signification of input parameters on tool wear is evaluated and discussed

From Agricultural Waste to Biofuel: Enzymatic Potential of a Bacterial Isolate Streptomyces fulvissimus CKS7 for Bioethanol Production

Purpose To avoid a negative environmental and economic impact of agricultural wastes, and following the principles of circular economy, the reuse of agricultural wastes is necessary. For this purpose, isolation of novel microorganisms with potential biotechnological application is recommended. The current researches in bioethanol production are aimed to reduce the production costs using low-cost substrates and in-house produced enzymes by novel isolated microorganisms. In line with this, in this study valorization of these agricultural by-products by novel isolate S. fulvissimus CKS7 to biotechnological value added products was done. Methods Standard microbiological methods were used for the isolation and characterization of strain. Enzymes activities were determinated using DNS method while, the ethanol concentration was determined based on the density of the alcohol distillate at 20 degrees C. Results The maximal enzymatic activities for amylase, cellulases (carboxymethyl cellulase and Avicelase), pectinase and xylanase were achieved using rye bran as a waste substrate for CKS7 growth. Obtained crude bacterial enzymes were used for enzymatic hydrolysis of lignocellulosic materials including horsetail waste, yellow gentian waste, corn stover, cotton material and corona pre-treated cotton material. The maximum yield of reducing sugars was obtained on horsetail waste and corona pre-treated cotton material. Waste brewer's yeast Saccharomyces cerevisiae was successfully used for the production of bioethanol using horsetail waste hydrolysate and corona pre-treated cotton material hydrolysate. Conclusion The obtained results showed that bacterial strain CKS7 has a significant, still unexplored enzymatic potential that could be used to achieve a cleaner, environmental friendly and economically acceptable biofuel production. [GRAPHICS]