Electrical discharge machining of polycrystalline diamond using copper electrode – finishing condition

Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1µs. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4µm was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1µs and 1µs respectively

Electrical discharge machining of polycrystalline diamond using copper electrode – finishing condition

Research on machining process of Polycrystalline Diamond (PCD) is becoming important as the material was believed suitable to be used for cutting tools of advanced aeronautical structure. Electrical Discharge Machining (EDM) was regarded as the suitable method to machine PCD due its noncontact process nature. The objective of this research is to determine the influence of several EDM parameter such as sparking current, pulse duration, and pulse interval to the material removal rate and surface roughness of the machined PCD. Instead of significantly influenced the material removal rate, the sparking current was also highly influenced tha surface roughness. Highest material removal rate of approximately 0.005mm3/s was recorded by the EDM process with the highest current used of 5A, and lowest pulse interval of 1µs. The influence of pulse duration is not clearly seen at the lowest pulse interval used. On the other hand, 0.4µm was the lowest surface roughness value obtained in this research indicated by the highest sparking current, highest sparking duration and lowest sparking interval of 5A, 1µs and 1µs respectively

Employment of fiber laser technology to weld austenitic stainless steel 304 l with aluminum alloy 5083 using pre-placed activating flux

The overlapping welding was carried out in keyhole mode between austenitic stainless steel 304 l and aluminum alloy 5083 using a low power fiber laser in continuous irradiation. The significant content of magnesium as the alloying element with low boiling point and high vapor pressure inside the AA 5083 matrix can induce the spatter formation and depression on surface of the weld beads upon laser beam absorption and temperature growth which can deteriorate the mechanical properties and appearance of the joints. To reduce these defects, a variety of single and multi-components activating fluxes including oxide-based TiO2 and halide-based CaF2 flux powders were pre-placed on the surface of welding material prior to laser welding. The EDX and XRD analyses in addition to microhardness and shear tests were carried out to characterize the joints. The obtained results showed that, the oxide and halide activating fluxes can significantly improve the joints' strength up to 1.48 and 1.85 times in average respectively compared with autogenous joint. It was deduced that the simultaneous effect of significant decrease in joints' surface depression leading to welds' geometry improvement in addition to less formation of interfacial Fe-Al intermetallics, were the major causes for considerable strength improvements. (C) 2015 Elsevier Ltd. All rights reserved

Declining concentration in UK manufacturing? A problem of measurement

It has become conventional wisdom that market concentration in the UK has fallen over recent history. However, the typical assumption has been that all imports are competitive so that any increase in import penetration implies a decline in market concentration. In a world of transnationally organized production and trade this would seem an inappropriate working assumption. Our analysis of the UK market for cars, vans, trucks and buses, where the necessary detailed firm data is available, supports this contention: an accurate assessment of who controls imports is crucial in the measurement of market concentration.

The Study of Plasticized Solid Polymer Blend Electrolytes Based on Natural Polymers and Their Application for Energy Storage EDLC Devices

In this work, plasticized magnesium ion-conducting polymer blend electrolytes based on chitosan:methylcellulose (CS:MC) were prepared using a solution cast technique. Magnesium acetate [Mg(CH3COO)2] was used as a source of the ions. Nickel metal-complex [Ni(II)-complex)] was employed to expand the amorphous phase. For the ions dissociation enhancement, glycerol plasticizer was also engaged. Incorporating 42 wt% of the glycerol into the electrolyte system has been shown to improve the conductivity to 1.02 × 10−4 S cm−1. X-ray diffraction (XRD) analysis showed that the electrolyte with the highest conductivity has a minimum crystallinity degree. The ionic transference number was estimated to be more than the electronic transference number. It is concluded that in CS:MC:Mg(CH3COO)2:Ni(II)-complex:glycerol, ions are the primary charge carriers. Results from linear sweep voltammetry (LSV) showed electrochemical stability to be 2.48 V. An electric double-layer capacitor (EDLC) based on activated carbon electrode and a prepared solid polymer electrolyte was constructed. The EDLC cell was then analyzed by cyclic voltammetry (CV) and galvanostatic charge–discharge methods. The CV test disclosed rectangular shapes with slight distortion, and there was no appearance of any redox currents on both anodic and cathodic parts, signifying a typical behavior of EDLC. The EDLC cell indicated a good cyclability of about (95%) for throughout of 200 cycles with a specific capacitance of 47.4 F/g

Adherence to Clinical Practice Guidelines (CPG) management of dengue infection in adults (revised 2nd edition)

The Malaysian Dengue Clinical Practice Guidelines (CPG) have been developed to provide evidence-based guidance in the management of dengue infections. The use of these guidelines is essential to ensure its recommendations are being practiced. However, the adherence to the guidelines for management of dengue (revised 2nd edition) by healthcare providers still remains unknown. Therefore, the aim of this study was to evaluate the proportion among healthcare providers that adhere to this Dengue CPG. A retrospective cohort study of dengue cases registered from 1 January 2014 to 1 June 2015 was conducted in public hospitals and health clinics in Selangor, Putrajaya and Kuala Lumpur. Adherence to the CPG recommendations were recorded by reviewing patients’ case notes. Overall proportion of adherence in clinical components of the recommendation were (7.1 to 100.0% versus 7.7 to 73.8%) in history taking, (6.7 to 100.0% versus 12.3 to 60.0%) in physical examinations, (18.4 to 100.0% versus 23.1 to 83.2%) in assessment of warning signs, (0.6 to 100.0% versus 12.3 to 87.7%) in assessment of haemodynamic status, (60.0 to 100.0% versus 27.7 to 40.0%) in diagnosis, (46.6 to 80.0% versus 52.3%) in case notifications, (73.2 to 100.0% versus 89.2 to 96.9%) in performing specific laboratory investigations and (7.9 to 100.0% versus 21.5%) in monitoring, for outpatient versus inpatient, respectively. Adherence trends were demonstrated to be higher in hospital settings compared to outpatient settings. Adherence to this Dengue CPG varies widely with overall good clinical outcomes observed

Influence of Microwave and Conventional Annealing Processes in Improving an Electrodeposited Nickel Interlayer Characteristics

Nickel interlayer was coated on tungsten carbide substrate by electrodeposition process for the purpose of diamond deposition. Conventional and microwave annealing processes were used to improve the adhesion strength and modify the surface composition of the electroplated nickel interlayer. The conventional annealing was conducted in a high-temperature tube furnace at 1323.15 K (1050 °C) for 20 and 60 minutes annealing durations. The microwave annealing was carried out in 2.45 GHz microwave furnace at 1303.15 K (1030 °C) for the same annealing durations as the conventional process. The annealed specimens were characterized by electron microscopy, Energy dispersive X-ray spectroscopy, and X-ray diffraction technique. Adhesion of the annealed nickel interlayer was assessed by the scratch test. The results revealed significant changes in the nickel coating composition, adhesion, and appearance. The adhesion strength of nickel interlayer annealed for the longer duration of the two processes is similar. For shorter annealing duration, the microwave-annealed coating showed better adhesion. The surface composition of the nickel interlayer was modified by the diffusion of carbon and tungsten during the microwave and conventional annealing, respectively. The microwave annealing is a promising process for producing good quality treated nickel-coated tungsten carbide specimens