Analysis of aircraft maintenance processes and cost

Abstract: The life cycle of an aircraft consists of design, production, operation and decommissioning phases. For an airline the main focus is on the maintenance process during the operation phase. This paper presents a case study of an airline facing a challenge of increasing maintenance cost. The objective is to understand factors that drive increase in cost. Maintenance cost, flight hours, flight cycles, dispatch reliability and pilot reports were analyzed to find out the maintenance cost drivers. The study identified that the aircraft which dominated the maintenance costs had the highest flight hours, and the lowest dispatch reliability in the fleet

Industrial sustainability in a challenged economy : the Zimbabwe steel industry

Abstract: The economy of Zimbabwe has deteriorated over the years with hyperinflation. In the years 2006 to 2008 the conditions worsened and in 2009 a multicurrency system including the US dollar was introduced, however investment in the industry did not strengthen and a number of challenges are still faced by the industry. A main feature of the Industry in Zimbabwe had been the steel and steel related manufacturing industry which was key for both domestic and foreign markets. The motivation for this study was to investigate and propose st rategies for enhancing sustainability of steel making companies in Zimbabwe. The aim of this research was to undertake a requirements analysis from the steel companies and identify the main challenges from the point of view of steel production. From these challenges the paper aimed to help codefine some of the possible solutions the companies could consider. Sharing the findings could help companies pick up best practice and inform policy makers in developing new frameworks for improving industrial sustainability

Enabling condition based maintenance in a precious metal processing plant

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Energy consumption and carbon footprint analysis of Fused Deposition Modelling: A case study of RP Stratasys Dimension SST FDM.

It is envisaged and expected that professional engineers, process and product developers plays an active role in the sustainable development of manufacturing activities to overcome the global challenges of depletion of natural resources, environmental pollution and damage to the ecosystems. This however calls for the necessity of the industry to adapt and improve on the various manufacturing processes employed for their products not only to keep up with global competition by reducing its variable costs, but also for the sustainable manufacture of their products. Rapid prototyping is one of the new 3D and additive manufacturing technology available globally. This technology has been viewed as a sustainable technology since it optimises electrical energy demand and promotes zero waste technology. This overstretched hypothesis need to be tested. This work evaluate the direct electrical energy demand in fused deposition modelling FDM machine using the Stratasys Dimension SST FDM as a case study and as a panacea to understudy the electrical energy requirement and carbon footprint for rapid prototyping

The effect of Auxiliary Units on the Power Consumption of CNC Machine tools at zero load cutting

Electricity consumptions have attracted global interest in recent times. This is attributable to the increasing technological advancement and new machines and materials development hence, an urgent global call for energy efficiency and sustainable manufacture. The electricity consumption in the manufacturing sector especially at the process level stages is an increasing trend. This is partly due to the energy demand of the auxiliary units and machine features incorporated into the machine tools at the design and manufacturing stages and on the other, as a result of increased production activities (increased product demand) during the use phase. This resulted in an increased embodied product energy that affects the cost and life cycle assessment of the product. In view of this economic and environmental objectives, it is paramount to investigate the energy consuming activities during machining (i.e. tip energy and zero load cutting energy) in order to optimize electricity demand at the secondary processing stages. In this work, the electrical energy demand of the auxiliary units and machine features of three different machine tools were investigated and characterized. This is required in order to encourage symbiotic and sustainable manufacture of products for resource optimization and also to determine specific areas for energy savings. It was observed that the electrical energy demand for non-cutting activities dominate the machining processes at more than 70% and the zero load cutting energy, which is machine dependent, is also about 14%. A step change in axes motor designs for CNC machine tools could facilitate energy reduction in this direction

Life cycle assessment of single-use and reusable plastic bottles in the city of Johannesburg.

Abstract: Polyethylene terephthalate (PET) bottles of water have experienced huge growth in demand and sales in South Africa. This expansion in use creates challenges as well as opportunities for managing the life cycle impact. The properties that make PET desirable for fluid-containing bottles have also made it highly resistant to environmental biodegradation. Reusable plastic bottles are now marketed as a solution to reduce the impact of single-use plastic bottles. We assessed the life cycle impact of single-use PET bottles and an alternative, reusable PET bottle based on consumption patterns in South Africa and the material flow and supply chain in the urban environment. This robust consideration of local conditions is important in evaluating the life cycle impact. In an examination of 13 impact categories, the reusable PET bottle had lower impact than the single-use bottle in all the impact categories examined. The mass of PET bottle material required to deliver the water needs at any given time is a dominant factor on the environmental burden. Extending the life of reusable bottles and designing lighter weight bottles would reduce their life cycle impact. Information obtained in evaluating alternatives to plastic water bottles can be valuable for providing a foundation assessment for policymakers and plastic bottle manufacturers to make informed choices and to focus on improvements in life cycle impact. Significance: • The significant impact of the production phase in the life cycle of both single-use and reusable PET bottles confirms the need to design a much more lightweight bottle to reduce the mass of materials used in production. • Another key consideration was the long transportation distance covered during the production phase, and the negative impact of current vehicular emissions. Municipalities and waste collectors should consider the use of low-carbon transport. • This study highlights the value of extending the life of plastic bottles, as well as recycling for material recovery, remanufacturing and repurposing these bottles within the City. • The use of fewer, larger single-use bottles compared with a greater number of smaller single-use bottles is discussed

Specific energy based characterization of tool wear in mechanical machining processes

The global trend for energy consumption as a foundational requirement for economic and social development is an increasing one. Electricity consumption is proportional to the CO2 emitted at the process level and especially for machining processes. The electrical energy demand during machining can be categorized and modelled as basic energy (energy demand by the machine tool while operating at zero load) and tip energy (energy for actual material removal – cutting). The tool tip energy is evaluated from the specific cutting energy. At present limited data exists with regards to the key parameters required for modelling the tip energy. Previous studies and data for specific energy were based on the normalisation of the total energy demand with the material removal rate and have not investigated the effect of tool wear. In this work, the impact of tool wear on the specific energy coefficients in machining were studied and modelled. Cutting tests were performed and tool wear and tool life based on the specific energy coefficient for each wear land value were evaluated. The study has for the first time provided data on the variation of specific cutting energy for higher tool wear lands and presents vital sensitivity analysis. With longer cutting time, tool wear increases which leads to higher specific cutting energy and energy consumption during machining. The specific energy coefficient increased by up to 50% when turning EN8 steel alloy between 2 and 10 passes. This knowledge is vital information for process planners and could enable energy estimates to be more accurate and realistic with regards to capturing the impact of tool wear

Effect of Cutting Parameters on Surface Finish when Turning Nitronic 33 Steel alloy

Nitronic 33 steel alloys are metallic alloys that exhibit characteristics such as high strength-to-weight ratio, outstanding corrosion and erosion resistant properties, and the ability to withstand cryogenic conditions and elevated temperatures. These characteristics of Nitronic 33 steel alloys make it popular in the fabrication of chemical processing, pollution control, aerospace equipment, and for steam and autoclave applications. Nitronic 33 steel alloy is classified as difficult-to-cut materials because of its high nitrogen content and the capability to form martensite as a result of high temperatures generated during mechanical machining and other subtractive manufacturing processes. This resulted in increased capacity and tooling cost during manufacturing. Therefore, there is the need to evaluate the optimum parameters when machining this alloy for sustainable and resource efficient machining. In this work, tool life, tool wear, surface roughness, cutting forces and power demand when turning Nitronic 33 steel alloy under different cutting environment were investigated. The result presented an optimum turning conditions at which Nitronic 33 steel alloy can be manufactured with minimum tool wear and surface integrity. The research outcome also addresses some of the problems encountered during the high speed machining of Nitronic 33 steel alloy that could influence manufacturing cost reduction. This work will also aid the general understanding of Nitronic 33 steel alloy with respect to sustainable and resource efficient machining

Circular economy ownership models : a view from South Africa industry

Abstract: The world is neither globally successful in remanufacturing and re-use of products nor recycling of waste materials. This requires a combination of circular economy management systems, business models and novel technologies. There are contrasting views in literature regarding models for a circular economy. The main views are built on extended producer responsibility and on the role of end users. This paper is based on a study of the South African industry’s view of circular economy models, drivers and sustainers, with particular focus on composite waste. Cost reduction was found to be the strongest driver and sustainer for recycling of composites. Thus, maximizing opportunities to reduce cost is a key factor in encouraging South African companies to embrace the circular economy. This is important in developing appropriate national models for managing the transition to a circular economy