Journal of Manufacturing and Materials Processing, 2022
Although laser drilling of carbon fibre-reinforced polymer (CFRP) composites offers the advantage... more Although laser drilling of carbon fibre-reinforced polymer (CFRP) composites offers the advantages of zero tool-wear and avoidance of fibre delamination compared with mechanical drilling, it consumes considerably more energy during the drilling process. This research shows that by using a new, stepped parameter parallel ring laser hole drilling method, an energy saving of 78.10% and an 18.37 gCO2 reduction for each hole, while improving productivity by more than 300%, can be achieved in laser drilling of 6 mm diameter holes in CFRP sheets of 2 mm in thickness, compared with previous laser drilling methods under the same drilling quality. The key reason for this is an increase in energy input to the inner rings enabling more rapid removal of the material, while the lower energy input for the outer ring provides a shielding trench to reduce the heat loss into the parent material. The results are compared with single-ring laser drilling and multiple-ring laser drilling with constant pr...
There is an urgent and growing need to further advance the plastic waste management system global... more There is an urgent and growing need to further advance the plastic waste management system globally and in South Africa, due to the increasing impact of plastic waste. This study focused on the adequacy of plastic policies to sustainably manage plastic waste. Policies need to address the plastic material supply systems and the options up the waste hierarchy for them to be effective and support material circularity. The study used qualitative content analysis to assess how the evolution of plastic policies for plastic waste management in South Africa aligned with national plastic material flows and promoted options higher up the waste hierarchy. This was benchmarked with Norway and Germany, which have some of the highest plastic recycling rates. The results showed that the evolution of existing plastic policies for South Africa addresses stages of production, trade and consumption, and recycling. There is no focus on waste generation, collection and sorting. None aligned with the was...
Water is becoming a scarce resource in many parts of the world, leading to increased competition ... more Water is becoming a scarce resource in many parts of the world, leading to increased competition amongst water users. Optimized water allocation is increasingly important to balance the growing demand for water and the limited supply of accessible clean water. The literature on water allocation schemes and decision support systems, developed for application in specific water management areas or watersheds, was critically reviewed. Although the literature is rich in studies on the application of a broad range of water allocation schemes, there is a lack of information available on the methodology and process of selecting the most applicable scheme that balances the local realities and requirements of stakeholders while considering the local context with regard to the economic, social and environmental impact of water usage. In this article, a framework is presented that water management practitioners can use to select applicable water allocation planning schemes and associated decisi...
The optimization of electrical energy demand is an important objective function in machining scie... more The optimization of electrical energy demand is an important objective function in machining science. This ensue minimum cost and specific energy demand of manufacturing processes. Mechanical machining as one of the major manufacturing processes consumed on average 38 TWh of electrical energy. This generated on average 16 million tones of CO2 emitted to the environment in the UK in 2012. Since carbon dioxide emission is attributable to electrical energy consumption, urgent action is required at all levels of machining processes in order to curtail the impact of electrical energy consumption on the environment through the optimization of process mechanisms. In this work, the specific cutting energy and process mechanisms were correlated in order to determine the efficiency of machining processes and to evaluate the specific energy optimization criterion for sustainable machining. The results show that for minimum energy demand and sustainable process mechanism, it is important that the ratio of the undeformed chip thickness to the cutting edge radius be equal or greater than 1. This ratio encourages shearing dominated mechanism and eliminates ploughing and rubbing at the tool-workpiece interface. This work could aid energy management for resource efficiency and sustainable manufacture of products at the production and process planning stages.
The International Journal of Advanced Manufacturing Technology, 2017
Manufacturing sustainability and minimal environmental impacts of machining processes could be ac... more Manufacturing sustainability and minimal environmental impacts of machining processes could be achieved by embracing energy demand reduction strategies. These may include the use of more efficient machine tool components (such as drives and pumps) and reduction in weights of materials being moved by the feed drive (machine table, vice, and workpiece material). However, it has not been defined in literature that energy saving approaches could be identified by studying the influence of toolpath strategies and machine tool axis configurations on the electrical energy requirements in a milling process. In this work, different toolpath strategies were considered for pocket milling of AISI 1018 steel on two threeaxis computer numerical control (CNC) milling machines. It was observed that machining on the y-axis of the conventional CNC milling machine and the x-axis of the high-speed CNC milling machining centre (axes carrying more weights) resulted in higher energy demand when compared with the lighter axis. This study also showed that the electrical energy efficiency of toolpath machining strategy varies from one CNC milling machine to another due to their structural configurations. This work also proposes fundamental measures of selecting the most efficient toolpath strategy for energy consumption management in mechanical machining. This could further raise the integrity of sustainable machining strategies for energy efficiency in the manufacturing industries. The knowledge obtained would aid in improving energy efficiency in mechanical machining and also reduce the environmental impacts.
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2020
Laser irradiation de-coating is a promising new approach for effective coating removal of cutting... more Laser irradiation de-coating is a promising new approach for effective coating removal of cutting tools. While this method has demonstrated feasibility for conventional coatings, its use and efficacy on lubricant coating is however yet to be ascertained. This paper reports on the results of excimer laser de-coating of hard DLC from DLC-coated tungsten carbide (WC) substrates. A range of fluence and pulse was studied to evaluate the effectiveness of the de-coating process. Result shows that laser parameters of 7 J/cm2 fluence, 400 pulse and 25 Hz frequency were found to yield optimum results in removing hard DLC coating of 3.2 μm thickness from WC substrates. The experimental work indicated successful laser de-coating of hard DLC coating without noticeable damage to the WC substrate. The capability of this new de-coating process is significant in the aerospace industry as it could facilitate re-grinding and recoating of drills thereby improving economics of manufacturing. The process...
International Journal of Machine Tools and Manufacture, 2005
High Speed Machining (HSM) is now recognised as one of the key processes in advanced machining te... more High Speed Machining (HSM) is now recognised as one of the key processes in advanced machining technology for automotive, die and mould, and aerospace industries. Machining of metals at high cutting speeds produces high temperatures in the primary shear zone, which ...
End-of-life waste disposal is a major issue in Malaysia, where the country’s economy has suffered... more End-of-life waste disposal is a major issue in Malaysia, where the country’s economy has suffered due to waste recovery issues. Many countries have successfully identified critical materials and products for increasing recycling rates, but not in Malaysia. Thus, the Malaysian government and businesses have had difficulty prioritising products for recycling. The absence of critical materials data has meant that a recovery strategy could not be planned wisely. In addition, the Product Recycling Desirability Model that was utilised by many countries to improve their recycling strategy could not be applied to Malaysia, as it requires critical materials data as input. To start with, Malaysia’s important materials have been identified. Next, two risk dimensions are defined: supply risk and material risk. The indicators are then weighted according to Malaysia’s scenarios. The scores are analyzed and applied to the Product Desirability Model to find desirable products for recycling. As a re...
There is an urgent and growing need to reduce the environmental footprints of products and manufa... more There is an urgent and growing need to reduce the environmental footprints of products and manufacturing processes and to support sustainable material consumption. For engineering applications this implies the need to develop low energy/carbon footprint manufacturing processes that utilise extended life tooling. In machining, nano-structured coatings can be used to extend service life of cutting tools. However, hard coatings pose a challenge to the reshaping and re-use of tools. This work investigated the use and re-use of cutting tools by developing selective tool coating removal using laser and conventional chemical de-coating technology. The laser de-coated tools were re-coated and their machining performance was compared to that of chemical decoated and re-coated tools as well as first generation coated and uncoated tools. The paper presents a comparison of the energy footprints associated with the re-use of tooling. It is concluded that high value tooling can exploit material re-use procedures.
In today's business environment, the trend towards more product variety and customization is unbr... more In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
Polyethylene terephthalate (PET) bottles of water have experienced huge growth in demand and sale... more 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 giv...
The International Journal of Advanced Manufacturing Technology, 2016
The environmental impact of conventional machining processes as influenced by the consumption of ... more The environmental impact of conventional machining processes as influenced by the consumption of electrical energy resources is one of the contributing factors to global warming potentials and pollution. This is as a result of CO 2 emission in the manufacturing process. Mechanical machining is one of the most commonly used processes and a major electrical energy consumer in manufacturing sector. In this paper, a framework is presented to validate the energy consumption model previously proposed using the computer numerical control (CNC) tool path and numerical control (NC) code characteristics. The CNC architecture was decomposed into energy-consuming units, and NC codes were parsed to estimate the electrical energy consumption. A test piece was designed in accordance with the ISO14955-3 standards on energy consumption estimation and followed through the CAD/CAM software to generate NC codes which were used in the machining trials on the Takisawa milling machine. The validation was carried out pre-process and post-process machining. The result shows that the e-smart software compares well with the actual machining operation when milling stainless steel 316L.
Journal of Manufacturing and Materials Processing, 2022
Although laser drilling of carbon fibre-reinforced polymer (CFRP) composites offers the advantage... more Although laser drilling of carbon fibre-reinforced polymer (CFRP) composites offers the advantages of zero tool-wear and avoidance of fibre delamination compared with mechanical drilling, it consumes considerably more energy during the drilling process. This research shows that by using a new, stepped parameter parallel ring laser hole drilling method, an energy saving of 78.10% and an 18.37 gCO2 reduction for each hole, while improving productivity by more than 300%, can be achieved in laser drilling of 6 mm diameter holes in CFRP sheets of 2 mm in thickness, compared with previous laser drilling methods under the same drilling quality. The key reason for this is an increase in energy input to the inner rings enabling more rapid removal of the material, while the lower energy input for the outer ring provides a shielding trench to reduce the heat loss into the parent material. The results are compared with single-ring laser drilling and multiple-ring laser drilling with constant pr...
There is an urgent and growing need to further advance the plastic waste management system global... more There is an urgent and growing need to further advance the plastic waste management system globally and in South Africa, due to the increasing impact of plastic waste. This study focused on the adequacy of plastic policies to sustainably manage plastic waste. Policies need to address the plastic material supply systems and the options up the waste hierarchy for them to be effective and support material circularity. The study used qualitative content analysis to assess how the evolution of plastic policies for plastic waste management in South Africa aligned with national plastic material flows and promoted options higher up the waste hierarchy. This was benchmarked with Norway and Germany, which have some of the highest plastic recycling rates. The results showed that the evolution of existing plastic policies for South Africa addresses stages of production, trade and consumption, and recycling. There is no focus on waste generation, collection and sorting. None aligned with the was...
Water is becoming a scarce resource in many parts of the world, leading to increased competition ... more Water is becoming a scarce resource in many parts of the world, leading to increased competition amongst water users. Optimized water allocation is increasingly important to balance the growing demand for water and the limited supply of accessible clean water. The literature on water allocation schemes and decision support systems, developed for application in specific water management areas or watersheds, was critically reviewed. Although the literature is rich in studies on the application of a broad range of water allocation schemes, there is a lack of information available on the methodology and process of selecting the most applicable scheme that balances the local realities and requirements of stakeholders while considering the local context with regard to the economic, social and environmental impact of water usage. In this article, a framework is presented that water management practitioners can use to select applicable water allocation planning schemes and associated decisi...
The optimization of electrical energy demand is an important objective function in machining scie... more The optimization of electrical energy demand is an important objective function in machining science. This ensue minimum cost and specific energy demand of manufacturing processes. Mechanical machining as one of the major manufacturing processes consumed on average 38 TWh of electrical energy. This generated on average 16 million tones of CO2 emitted to the environment in the UK in 2012. Since carbon dioxide emission is attributable to electrical energy consumption, urgent action is required at all levels of machining processes in order to curtail the impact of electrical energy consumption on the environment through the optimization of process mechanisms. In this work, the specific cutting energy and process mechanisms were correlated in order to determine the efficiency of machining processes and to evaluate the specific energy optimization criterion for sustainable machining. The results show that for minimum energy demand and sustainable process mechanism, it is important that the ratio of the undeformed chip thickness to the cutting edge radius be equal or greater than 1. This ratio encourages shearing dominated mechanism and eliminates ploughing and rubbing at the tool-workpiece interface. This work could aid energy management for resource efficiency and sustainable manufacture of products at the production and process planning stages.
The International Journal of Advanced Manufacturing Technology, 2017
Manufacturing sustainability and minimal environmental impacts of machining processes could be ac... more Manufacturing sustainability and minimal environmental impacts of machining processes could be achieved by embracing energy demand reduction strategies. These may include the use of more efficient machine tool components (such as drives and pumps) and reduction in weights of materials being moved by the feed drive (machine table, vice, and workpiece material). However, it has not been defined in literature that energy saving approaches could be identified by studying the influence of toolpath strategies and machine tool axis configurations on the electrical energy requirements in a milling process. In this work, different toolpath strategies were considered for pocket milling of AISI 1018 steel on two threeaxis computer numerical control (CNC) milling machines. It was observed that machining on the y-axis of the conventional CNC milling machine and the x-axis of the high-speed CNC milling machining centre (axes carrying more weights) resulted in higher energy demand when compared with the lighter axis. This study also showed that the electrical energy efficiency of toolpath machining strategy varies from one CNC milling machine to another due to their structural configurations. This work also proposes fundamental measures of selecting the most efficient toolpath strategy for energy consumption management in mechanical machining. This could further raise the integrity of sustainable machining strategies for energy efficiency in the manufacturing industries. The knowledge obtained would aid in improving energy efficiency in mechanical machining and also reduce the environmental impacts.
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2020
Laser irradiation de-coating is a promising new approach for effective coating removal of cutting... more Laser irradiation de-coating is a promising new approach for effective coating removal of cutting tools. While this method has demonstrated feasibility for conventional coatings, its use and efficacy on lubricant coating is however yet to be ascertained. This paper reports on the results of excimer laser de-coating of hard DLC from DLC-coated tungsten carbide (WC) substrates. A range of fluence and pulse was studied to evaluate the effectiveness of the de-coating process. Result shows that laser parameters of 7 J/cm2 fluence, 400 pulse and 25 Hz frequency were found to yield optimum results in removing hard DLC coating of 3.2 μm thickness from WC substrates. The experimental work indicated successful laser de-coating of hard DLC coating without noticeable damage to the WC substrate. The capability of this new de-coating process is significant in the aerospace industry as it could facilitate re-grinding and recoating of drills thereby improving economics of manufacturing. The process...
International Journal of Machine Tools and Manufacture, 2005
High Speed Machining (HSM) is now recognised as one of the key processes in advanced machining te... more High Speed Machining (HSM) is now recognised as one of the key processes in advanced machining technology for automotive, die and mould, and aerospace industries. Machining of metals at high cutting speeds produces high temperatures in the primary shear zone, which ...
End-of-life waste disposal is a major issue in Malaysia, where the country’s economy has suffered... more End-of-life waste disposal is a major issue in Malaysia, where the country’s economy has suffered due to waste recovery issues. Many countries have successfully identified critical materials and products for increasing recycling rates, but not in Malaysia. Thus, the Malaysian government and businesses have had difficulty prioritising products for recycling. The absence of critical materials data has meant that a recovery strategy could not be planned wisely. In addition, the Product Recycling Desirability Model that was utilised by many countries to improve their recycling strategy could not be applied to Malaysia, as it requires critical materials data as input. To start with, Malaysia’s important materials have been identified. Next, two risk dimensions are defined: supply risk and material risk. The indicators are then weighted according to Malaysia’s scenarios. The scores are analyzed and applied to the Product Desirability Model to find desirable products for recycling. As a re...
There is an urgent and growing need to reduce the environmental footprints of products and manufa... more There is an urgent and growing need to reduce the environmental footprints of products and manufacturing processes and to support sustainable material consumption. For engineering applications this implies the need to develop low energy/carbon footprint manufacturing processes that utilise extended life tooling. In machining, nano-structured coatings can be used to extend service life of cutting tools. However, hard coatings pose a challenge to the reshaping and re-use of tools. This work investigated the use and re-use of cutting tools by developing selective tool coating removal using laser and conventional chemical de-coating technology. The laser de-coated tools were re-coated and their machining performance was compared to that of chemical decoated and re-coated tools as well as first generation coated and uncoated tools. The paper presents a comparison of the energy footprints associated with the re-use of tooling. It is concluded that high value tooling can exploit material re-use procedures.
In today's business environment, the trend towards more product variety and customization is unbr... more In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
Polyethylene terephthalate (PET) bottles of water have experienced huge growth in demand and sale... more 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 giv...
The International Journal of Advanced Manufacturing Technology, 2016
The environmental impact of conventional machining processes as influenced by the consumption of ... more The environmental impact of conventional machining processes as influenced by the consumption of electrical energy resources is one of the contributing factors to global warming potentials and pollution. This is as a result of CO 2 emission in the manufacturing process. Mechanical machining is one of the most commonly used processes and a major electrical energy consumer in manufacturing sector. In this paper, a framework is presented to validate the energy consumption model previously proposed using the computer numerical control (CNC) tool path and numerical control (NC) code characteristics. The CNC architecture was decomposed into energy-consuming units, and NC codes were parsed to estimate the electrical energy consumption. A test piece was designed in accordance with the ISO14955-3 standards on energy consumption estimation and followed through the CAD/CAM software to generate NC codes which were used in the machining trials on the Takisawa milling machine. The validation was carried out pre-process and post-process machining. The result shows that the e-smart software compares well with the actual machining operation when milling stainless steel 316L.
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Papers by Paul Mativenga