Effect of hot press forging process on different chip size, pre-compaction cycle, and holding time in direct recycling of aluminium alloy AA6061

A new approach of solid-state direct recycling metal chip was examined scientifically by applying hot press forging process technique. The study is to determine the effect of different chip sizes (S), pre-compaction cycle (PCC) and holding time (t) on the mechanical and physical properties of the recycled chip of AA6061 aluminium alloy in hot press forging process. Full-factorial design coupled with response surface methodology (RSM) design was used based on the face centred, central composite design (CCD) to evaluate the effects of three main parameters as mentioned above. The mechanical properties of recycled chips were determined by measuring the ultimate tensile strength (UTS) and yield strength (YS) whereas the physical properties were studied by examining the microhardness, microstructure, and the relative density of the recycled chip. Finally, both results of mechanical and physical properties of the recycled chips were compared with the original AA6061 aluminium billet. The experimental results indicates that, hot pressed AA6061 recycled aluminium alloy using chip size (S=larger), pre-compaction cycle (PCC=4 times), and holding time (t=120 minutes) produced the higher value of UTS and YS at 122.33 MPa and 120.45 MPa respectively, which is 42% of as-received billet. It was also found that larger S used with higher number of PPC and longer the t will produce better mechanical and physical properties of the recycled AA6061 chip where t has most influential effect throughout the process followed by PCC, and S. Those results were supported by RSM optimization technique giving 98% of desirability index as both solution predicted was close to the experimental value of the reference specimen. Therefore, this study can be used as an alternative technique for recycling aluminium chips instead of conventional method which it has been carried out below the melting phase temperature

Characteristics of leachate upon hydrothermal treatment processing: case study of Ampang district municipal solid waste leachate

Municipal solid waste (MSW) leachate is a hazardous liquid produced from decomposition of solid waste with high amount of organic matter and ammonia-nitrogen with obnoxious smell. This study aimed to investigate the behavior of MSW leachate when subjected to hydrothermal treatment using an autoclave set up at below water critical points (temperatures of 100 °C, 150 °C, and 200 °C at 0.1 MPa, 0.4 MPa and 1.6 MPa, respectively) with 15 min and 60 min holding time. Physicochemical characterization of the setup at 200 °C and 1.6 MPa at 60 min holding time indicates a feasible parameter when materials that caused the dark color and obnoxious smell were almost completely removed. Over 99% of chemical oxygen demand and ammonia nitrogen was eliminated when treated with hydrothermal treatment and yielded a condensed liquid product that complied with permissible limits set by the National Water Quality Standard Malaysia and the World Health Organization for wastewater discharges for irrigation purposes. Chromatographic analysis indicated that most of the organic compounds present in the raw leachate was removed. This processing is believed to be an environmentally friendly method that can treat MSW leachate rapidly, and it has the potential to be used as an effective alternative to existing leachate treatment technologies

Development of a novel zero point setting device for high speed and micro machining applications

In CNC machining, high downtimes of machine tools are associated with the tool zero point setting in the absence of automatic setting devices. The problem is more acute in high speed and micro-machining processes dealing with micron and sub micrometer range depth of cut which precise require zero point setting. Hence there is a high demand for reliable and cost-effective zero-point setting devices. The majority of conventional, and some CNC, machine-tools do not have an integrated zero point setting device. Therefore, the determination of the zero point during metal cutting is currently done by a trial and error method and the accuracy of positioning of the tool especially in the case of micro-machining is not satisfactory and poses a challenging problem. The available zero point setting devices are extremely sophisticated electronic instruments, which are very expensive with unit prices ranging up to US$ 30,000. Also, the operation of such devices demands very skilled machinists and trained operators. The novel zero-point setting system, developed by the authors, uses the available equipments in a normal machining laboratory to detect the zero point with a good degree of accuracy and repeatability. One of the terminals of the device is connected to the tool holder and the other to the work-piece fixture using screws. When physical contact is established, between the tool and the work-piece/fixture element, a flashing LED light and a sounding buzzer are activated indicating that the circuit has been closed and the tool zero point is attained. The electric circuit arrangement of the device ensures high sensitivity to actual physical contact and a minimum resolution which is equal to the relevant machine’s minimum move (less than 0.1 μm for grinding operations). Thus, this device can play a vital role for precisely setting the zero point (or starting point) for micro-machining, and reducing the non-productive downtime of machine-tools and extra training of the relevant personnel. The total expenditure for the construction of this device was about RM 50 and it can be easily attached to vertical and horizontal milling machines, drilling machine, grinders, lathes, or machining centers. It can also be used with non-conductive work-pieces like glass, plastic and ceramics. Therefore, with this cost effective, reliable, and accurate device it is possible to make manufacturing processes more precise, rapid, economical, and productive

Characterization of municipal solid waste in Malaysia for energy recovery

Municipal solid waste (MSW) generation that grows continuously without proper management become worrying phenomenon. Currently, Malaysia is dependent on landfills with almost 85% of waste collected ending up in dumpsites. In order to propose an alternative for solid waste management plan instead of landfill, and to develop a waste-to-energy (WtE) system, the details study of municipal solid waste (MSW) generated is crucial. This paper presents a proposal for energy recovery to produce RDF by studying the characterization of MSW generated in Malaysia; the physical and chemical properties (proximate and ultimate analysis, calorific value or energy content, and thermal analysis) of the waste components to produce a high-quality RDF. The raw MSW sample consisted of 45% organics and food waste, 13% plastics, 9% papers, and 12% diapers. For raw MSW sample, total moisture content, ash content, volatile matter, and fixed carbon were 14.60%, 7.05%, 69.35% and 9% respectively. Gross calorific value is 4538 kcal/kg and carbon content are 45%. The optimum produced RDF sample was found at operating temperature 400°C with total moisture content, ash content, volatile matter, and fixed carbon were 0.75%, 21.65%, 48.35% and 29.22% respectively. Gross calorific value is 6600.15 kcal/kg and carbon content are 64%