Experimental Investigations & Effects of Cutting Variables on MRR and Tool Wear for AISI S2 Tool Steel

AbstractMachining is the most important of the manufacturing processes which involves the process of removing material from a work piece in the form of chips. Machining is necessary where tight tolerances on dimensions and finishes are required. Generally a machining process involves a large number of variables that affect its performance. Some of them are cutting parameters, geometry of cutting tool, coolant conditions, properties of tool material, properties of work piece, machine capabilities, etc. Among them, cutting parameters have profound effect on all kinds of performances when the same tool material and the same work piece material are used for machining. Therefore cutting parameters of speed, feed and depth of cut are considered as the process control variables and two important performance measures of CNC turning, namely, Metal Removal Rate (MRR) and Tool wear (TW) are considered for investigation. This paper presents the experimental investigations on the effects of cutting variables like Spindle speed, Feed and Depth of cut on the Material removal rate and tool wear. The experiments were conducted on AISI S2 tool steel grade on a CNC turning machine using carbide insert. The experiments were conducted as per the design of experiments. Initial trial experiments were conducted to fix the ranges for the control parameters. After conducting the experiments the MRR and Tool wear were measured and recorded. The effects were studied after plotting the graphs between the Input process parameters versus the responses using Design expert software. The results obtained in this study can by further used for optimizing the process parameters there by the optimized results help the operator to enhance the quality as well as machining rate

Polypropylene/Layered Double Hydroxide Nanocomposites: Influence of LDH Intralayer Metal Constituents on the Properties of Polypropylene

Sonication-assisted delamination of layered double hydroxides (LDHs) resulted in smaller-sized LDH nanoparticles (∼50-200 nm). Such delaminated Co-Al LDH, Zn-Al LDH, and Co-Zn-Al LDH solutions were used for the preparation of highly dispersed isotactic polypropylene (iPP) nanocomposites. Transmission electron microscopy and wide-angle X-ray diffraction results revealed that the LDH nanoparticles were well dispersed within the iPP matrix. The intention of this study is to understand the influence of the intralayer metal composition of LDH on the various properties of iPP/LDH nanocomposites. The sonicated LDH nanoparticles showed a significant increase in the crystallization rate of iPP; however, not much difference in the crystallization rate of iPP was observed in the presence of different types of LDH. The dynamic mechanical analysis results indicated that the storage modulus of iPP was increased significantly with the addition of LDH. The incorporation of different types of LDH showed no influence on the storage modulus of iPP. But considerable differences were observed in the flame retardancy and thermal stability of iPP with the type of LDH used for the preparation of nanocomposites. The thermal stability (50% weight loss temperature (T0.5)) of the iPP nanocomposite containing three-metal LDH (Co-Zn-Al LDH) is superior to that of the nanocomposites made of two-metal LDH (Co-Al LDH and Zn-Al LDH). Preliminary studies on the flame-retardant properties of iPP/LDH nanocomposites using microscale combustion calorimetry showed that the peak heat release rate was reduced by 39% in the iPP/Co-Zn-Al LDH nanocomposite containing 6 wt % LDH, which is higher than that of the two-metal LDH containing nanocomposites, iPP/Co-Al LDH (24%) and iPP/Zn-Al LDH (31%). These results demonstrated that the nanocomposites prepared using three-metal LDH showed better thermal and flame-retardant properties compared to the nanocomposites prepared using two-metal LDH. This difference might be due to the better char formation capability of three-metal LDH compared to that of two-metal LDH

Oral Contraceptive Pills Are Not a Risk Factor for Deep Vein Thrombosis or Pulmonary Embolism After Arthroscopic Shoulder Surgery

Background: Worldwide, more than 100 million women between the ages of 15 and 49 years take oral contraceptive pills (OCPs). OCP use increases the risk of venous thromboembolism (VTE) through its primary drug, ethinylestradiol, which slows liver metabolism, promotes tissue retention, and ultimately favors fibrinolysis inhibition and thrombosis. Purpose: To evaluate the effects of OCP use on VTE after arthroscopic shoulder surgery. Study Design: Cohort study; Level of evidence, 3. Methods: A large national payer database (PearlDiver) was queried for patients undergoing arthroscopic shoulder surgery. The incidence of VTE was evaluated in female patients taking OCPs and those not taking OCPs. A matched group was subsequently created to evaluate the incidence of VTE in similar patients with and without OCP use. Results: A total of 57,727 patients underwent arthroscopic shoulder surgery from 2007 to 2016, and 26,365 patients (45.7%) were female. At the time of surgery, 924 female patients (3.5%) were taking OCPs. The incidence of vascular thrombosis was 0.57% (n = 328) after arthroscopic shoulder surgery, and there was no significant difference in the rate of vascular thrombosis in male or female patients (0.57% vs 0.57%, respectively; P \u3e .99). The incidence of VTE in female patients taking and not taking OCPs was 0.22% and 0.57%, respectively (P = .2). In a matched-group analysis, no significant difference existed in VTE incidence between patients with versus without OCP use (0.22% vs 0.56%, respectively; P = .2). On multivariate analysis, hypertension (odds ratio [OR], 2.00; P \u3c .001) and obesity (OR, 1.43; P = .002) were risk factors for VTE. Conclusion: OCP use at the time of arthroscopic shoulder surgery is not associated with an increased risk of VTE. Obesity and hypertension are associated with a greater risk for thrombolic events, although the risk remains very low. Our findings suggest that patients taking OCPs should be managed according to the surgeon’s standard prophylaxis protocol for arthroscopic shoulder surgery

Novel peptides of therapeutic promise from Indian conidae

Highly structured small peptides are the major toxic constituents of the venom of cone snails, a family of widely distributed predatory marine molluscs. These animals use the venom for rapid prey immobilization. The peptide components in the venom target a wide variety of membrane-bound ion channels and receptors. Many have been found to be highly selective for a diverse range of mammalian ion channels and receptors associated with pain-signaling pathways. Their small size, structural stability, and target specificity make them attractive pharmacologic agents. A select number of laboratories mainly from the United States, Europe, Australia, Israel, and China have been engaged in intense drug discovery programs based on peptides from a few snail species. Coastal India has an estimated 20-30% of the known cone species; however, few serious studies have been reported so far. We have begun a comprehensive program for the identification and characterization of peptides from cone snails found in Indian Coastal waters. This presentation reviews our progress over the last 2 years. As expected from the evolutionary history of these venom components, our search has yielded novel peptides of therapeutic promise from the new species that we have studied

Assessment of trace metal contamination in a historical freshwater canal (Buckingham Canal), Chennai, India

The present study was done to assess the sources and the major processes controlling the trace metal distribution in sediments of Buckingham Canal. Based on the observed geochemical variations, the sediments are grouped as South Buckingham Canal and North Buckingham Canal sediments (SBC and NBC, respectively). SBC sediments show enrichment in Fe, Ti, Mn, Cr, V, Mo, and As concentrations, while NBC sediments show enrichment in Sn, Cu, Pb, Zn, Ni, and Hg. The calculated Chemical Index of Alteration and Chemical Index of Weathering values for all the sediments are relatively higher than the North American Shale Composite and Upper Continental Crust but similar to Post-Archaean Average Shale, and suggest a source area with moderate weathering. Overall, SBC sediments are highly enriched in Mo, Zn, Cu, and Hg (geoaccumulation index (Igeo) class 4– 6), whereas NBC sediments are enriched in Sn, Cu,Zn, and Hg (Igeo class 4–6). Cu, Ni, and Cr show higher than Effects-Range Median values and hence the biological adverse effect of these metals is 20%; Zn, which accounts for 50%, in the NBC sediments, has a more biological adverse effect than other metalsfound in these sediments. The calculated Igeo, Enrichment Factor, and Contamination Factor values indicate that Mo, Hg, Sn, Cu, and Zn are highly enriched in the Buckingham Canal sediments, suggesting the rapid urban and industrial development of Chennai MetropolitanCity have negatively influenced on the surrounding aquatic ecosystem

Tectonic stress field in the Indian subcontinent

A map of maximum horizontal compressive stress orientation in the Indian subcontinent has been prepared using orientations derived from three different stress indicators: borehole elongation breakouts, in situ hydraulic fracturing measurements, and earthquake focal mechanisms. Most part of the subcontinent appears to be characterized by a compressional stress regime (thrust and strike-slip faulting) imposed by plate boundary forces although SHmax orientations do not, in general, show clear correlation with the direction of motion of the Indian plate. Four provinces are recognized on the basis of regionally consistent orientations. These are the midcontinent stress province, the southern shield, the Bengal basin, and the Assam wedge. Their boundaries have been determined taking into consideration regional tectonics and seismicity. Central and northern India, including the Shillong Plateau stretching up to the great Himalaya, Pakistan, and Nepal are included in a broad midcontinent stress province characterized by NNE-ENE oriented SHmax.The mean orientation of SHmax in this province is N23°E, subparallel to the direction of compression expected to arise from he net resistive forces at the Himalayan collision zone, suggesting that it is largely determined by the tectonic collision processes. Much of southern India (Mysore plateau and the high-grade metamorphic terrain south of the plateau) appears to be part of a second stress province characterized by NW oriented SHmax. These appear close to those of the intraplate stress field prevailing in the central Indian Ocean. A third stress province was recognized in the Bengal basin including parts of West Bengal, Tripura, Manipur, and Mizoram in northeastern India and most of Bangladesh. This province extends eastward from the marginal fault in the western margin of the Bengal basin to the Indo-Burma subduction zone and is bounded on the north by the E-W striking Dauki fault.SHmax within the sedimentary pile of the Bengal basin is oriented in E-W direction, while P axes of earthquakes within the basement and the crust beneath the basin and within the subducted slab of the Indian plate beneath the Indo-Burman ranges generally trend north-N30°E. SHmax orientations within the sedimentary pile of the basin are parallel to the local (approximately E-W) direction of the convergence of Indian and Burmese plates, suggesting a casual relation to the resistive forces at the subduction zone in he Indo-Burma region. Interestingly, the stress field in the basement and the crust beneath the Bengal basin and in the subducted slab is similar to the one prevailing in the midcontinent stress province. Assam wedge stress region occupies the northeastern corner of the Indian plate, including Upper Assam, Arunachal Pradesh, and much of Nagaland. This region subducts beneath a sharply bent continental collision boundary consisting of the northeastern limb of the Himalayan and northern limb of the Indo-Burman fold belts. As a result, the stress field in this province is depth-differentiated and most likely responsible for the absence of consistent SHmax directions