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Nellore, India

News Article
Site: http://phys.org/technology-news/

Dr. Komgrit Lawanwong and colleagues have engineered some subtle refinements to metal forming techniques that allowed them to prevent a difficult problem called "springback," which plagues the process of bending high-strength steel (HSS). Their results appear in the Journal of Materials Processing Technology. High-strength steel is widely used in automotive structural components to help them withstand impacts without increasing their body weight. This has potential environmental benefits, as lightweight cars burn less fuel, and therefore have lower emissions. The most serious problem in the press-forming of these steel sheets is their extremely large 'springback'—which is the tendency of a metal to return to its original shape after compression or stretching. A simple example of springback is the small gap that will remain if you fold a metal sheet in the middle with your fingers and then release it. On an industrial scale, springback causes defects when metals are press formed. "The problems become particularly acute when high-strength materials are used," Dr. Komgrit said. "So a new technique to eliminate springback is urgently needed in the stamping industry." To make a U-shaped channel, three geometrical qualities are important, he explains: a precise bending angle with no springback, a sharp corner bend, and a flat bottom. To avoid these problems, the Hiroshima group proposed a four-step process: clamping of a sheet between a punch and a counter punch; U-bending while maintaining constant clamping force; pushing up of the bottom section of the U-bend with a counter punch; and removing the sheet from the die. The new component of this process is the counterpunching. To study the effectiveness of this new technique the researchers compared it with the existing approach on 980Y steel—a high-strength metal. With the existing method, a large degree of springback was seen, and the bottom part of the U-bend remained curved. "On the other hand, the new method delivered the best result for the springback angle—almost zero—together with a flat bottom," the researchers note. "Springback is becoming more of a problem as we try to use high-strength materials in many applications," Dr. Komgrit said. "This method is a useful way to eliminate the springback of high-strength steel in press forming." Explore further: Rough times: NIST's new approach to surface profiling More information: L. Komgrit et al. Elimination of springback of high-strength steel sheet by using additional bending with counter punch, Journal of Materials Processing Technology (2016). DOI: 10.1016/j.jmatprotec.2015.08.029

News Article
Site: http://phys.org/chemistry-news/

A touchscreen is an essential feature of many modern devices, but the material that gives most screens their touch sensitivity is in short supply. By adapting newspaper printing technology, A*STAR researchers have developed a low-cost alternative capable of printing conductive metal ink in lines so thin that they are invisible to the naked eye. A film of this fine metal mesh could potentially form the touch-sensing layer of future smartphone screens. Most touchscreens rely on an electrically conductive material called indium tin oxide (ITO). As skin is conductive, touching the screen alters its electric field, which is detected as a tap. Crucially for a surface layer of a screen, ITO is also optically transparent. Very few materials possess this combination of properties. Industry has responded to the spike in indium prices accompanying the rising demand for ITO by intensifying the search for alternative transparent conductive materials. XinQuan Zhang from the Singapore Institute of Manufacturing Technology and his co-workers are working on a promising alternative touch-sensitive film: a printed, mesh-like pattern of ultra-fine metal lines, created using roll-to-roll gravure printing. Gravure printing traditionally uses an etched mold to transfer ink on to paper. Here, the etched cylindrical mold instead transfers a precise pattern of conductive metal ink on to the touch-sensing substrate. Light from the screen passes through the holes in the printed mesh. Before this study, the finest lines that could be printed this way were approximately 50 micrometers wide, which blocked more than a third of the screen's light. Zhang and his co-workers have overcome this limitation through diamond micro engraving. Instead of using a laser to etch the grid-like pattern of tiny inkwells into the printer's cylindrical mold, Zhang uses a tiny diamond-tipped cutting tool to pattern the roller using ultraprecision machining technology. Originally developed to manufacture lenses and optical components, "ultraprecision machining has never been used for gravure printing," Zhang says. His team successfully adapted the machine to cut tiny inkwells on the roller, two and a half times smaller than a laser could etch. Using this roller, the team printed a mesh of metal lines just 19 micrometers across. More than 80 per cent of visible light passed through this mesh, matching ITO's optical performance. Although ultraprecision machining can produce very finely patterned rollers, the process is slow, says Zhang. "This is one disadvantage compared to lasers," he says. Next the team will "improve the process of ultraprecision machining to make it faster, so the roller mold will be affordable to industry." Explore further: Collecting the sun's energy: Novel electrode for flexible thin-film solar cells More information: XinQuan Zhang et al. Diamond micro engraving of gravure roller mould for roll-to-roll printing of fine line electronics, Journal of Materials Processing Technology (2015). DOI: 10.1016/j.jmatprotec.2015.05.032

Sravani K.,Processing Technology | Balasubramanian A.,Processing Technology | Vanitha M.,Processing Technology | Reddy G.V.S.,Processing Technology
Ecology, Environment and Conservation | Year: 2013

Quality of frozen Labeo rohita (Rohu) stored at -40°C was evaluated through proximate, biochemical, microbial and sensory analyses. After 90 days of storage, frozen fish were found with reduced moisture, lipid and protein content while the ash content fluctuated throughout the storage period. The organoleptic quality of the frozen stored fish was influenced by the Total Volatile Base Nitrogen (TVBN). Thiobarbutric acid (TBA), Free Fatty Acids (FFA) and microbial counts. Total Plate Count of mesophilic bacteria increased gradually from a log value of 2.85 cfu/gram of meat on 1st day of storage to 3.12 cfu/gram of meat on 30thday and decreased to 2.67 cfu/gram of meat on 90th day of frozen storage. Staphylococcus aureus count decreased from the first day storage count of 2.21 cfu/gram of meat to Est. < 1.0 cfu/gram of meat on 90thday. The psychrophilic count of rohu increased with storage period from an initial log value of 2.73 cfu/ gram of meat to 3.24 cfu/gram of meat up to 90th day of storage. Whereas the sulphur producing bacterial count increased up to 30th day of storage and then showed a decreasing trend. In the case of other mesophilic and psychrophilic bacteria such as E.coli, Faecal strepto cocci, Pseudomonas spp., Aeromonas spp., and other pathogenic microorganisms like Vibrio spp., Salmonella spp. and Listeria monocytogens were absent throughout the frozen storage period. The freshness based on over all sensory score decreased with increase in storage period. On correlating the overall sensory score with frozen storage period, the frozen stored fish was found acceptable for consumption upto 113 days. © EM International. Source

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