A dynamic simulation of a lean and agile manufacturing system
- Mutingi, M., Mbohwa, Charles, Mhlanga, S.
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S.
- Date: 2013
- Subjects: Agile manufacturing , Lean thinking , Manufacturing systems
- Type: Article
- Identifier: uj:4947 , http://hdl.handle.net/10210/13047
- Description: The integration of just-in-time and lean principles in agile manufacturing plays an important role in enhancing the operational performance of manufacturing systems. In this paper, we address this issue by (i) building a set of performance criteria for a typical manufacturing system, (ii) developing a system dynamics model for the system, and (iii) performing experimental “what-if” simulation analyses. Using a system dynamics simulation methodology, the impact of the application of lean and just-in-time policies on a traditional inventory-focused manufacturing system is investigated. System dynamics modelling is used to capture the dynamic causal linkages between different components of the manufacturing system. Different scenarios are generated in order to investigate the dynamics of the system under assumed demand scenarios. The results of the simulation study reveal that manufacturing systems can benefit from the introduction of lean and just-in-time principles, depending on the extent to which the necessary structural changes are implemented. The paper concludes by providing useful managerial insights for effective implementation of lean and agile manufacturing concepts.
- Full Text:
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S.
- Date: 2013
- Subjects: Agile manufacturing , Lean thinking , Manufacturing systems
- Type: Article
- Identifier: uj:4947 , http://hdl.handle.net/10210/13047
- Description: The integration of just-in-time and lean principles in agile manufacturing plays an important role in enhancing the operational performance of manufacturing systems. In this paper, we address this issue by (i) building a set of performance criteria for a typical manufacturing system, (ii) developing a system dynamics model for the system, and (iii) performing experimental “what-if” simulation analyses. Using a system dynamics simulation methodology, the impact of the application of lean and just-in-time policies on a traditional inventory-focused manufacturing system is investigated. System dynamics modelling is used to capture the dynamic causal linkages between different components of the manufacturing system. Different scenarios are generated in order to investigate the dynamics of the system under assumed demand scenarios. The results of the simulation study reveal that manufacturing systems can benefit from the introduction of lean and just-in-time principles, depending on the extent to which the necessary structural changes are implemented. The paper concludes by providing useful managerial insights for effective implementation of lean and agile manufacturing concepts.
- Full Text:
Design of an automated grinding media charging system for ball mills
- Rupare, W.F., Nyanga, L., Van der Merwe, A.F., Matope, S., Mhlanga, S.
- Authors: Rupare, W.F. , Nyanga, L. , Van der Merwe, A.F. , Matope, S. , Mhlanga, S.
- Date: 2013
- Subjects: Mill load , Grinding production ratio
- Type: Article
- Identifier: uj:4919 , http://hdl.handle.net/10210/13019
- Description: The parameters of mill load (ML) not only represent the load of the ball mill, but also determine the grinding production ratio (GPR) of the grinding process. Monitoring and recognition of milling conditions have significant effect on the operating efficiency, product quality, and energy and grinding media consumption for the milling circuit. This paper presents an automated grinding media charging system incorporating a multi-agent system developed in Java Agent Development Environment (JADE). A control logix program is designed to determine the precise quantities of grinding media to be charged in an incremental manner such that shock loading is avoided. The multi-agent system created in JADE monitors the power drawn and the mill load of the ball mill such that proper charging conditions are established. High quality of the regulation process is achieved through utilization of the control logix and the multi-agent system.
- Full Text:
- Authors: Rupare, W.F. , Nyanga, L. , Van der Merwe, A.F. , Matope, S. , Mhlanga, S.
- Date: 2013
- Subjects: Mill load , Grinding production ratio
- Type: Article
- Identifier: uj:4919 , http://hdl.handle.net/10210/13019
- Description: The parameters of mill load (ML) not only represent the load of the ball mill, but also determine the grinding production ratio (GPR) of the grinding process. Monitoring and recognition of milling conditions have significant effect on the operating efficiency, product quality, and energy and grinding media consumption for the milling circuit. This paper presents an automated grinding media charging system incorporating a multi-agent system developed in Java Agent Development Environment (JADE). A control logix program is designed to determine the precise quantities of grinding media to be charged in an incremental manner such that shock loading is avoided. The multi-agent system created in JADE monitors the power drawn and the mill load of the ball mill such that proper charging conditions are established. High quality of the regulation process is achieved through utilization of the control logix and the multi-agent system.
- Full Text:
Designing of an intelligent fuzzy logic system for accretion prevention in Sponge iron SL/RN rotary KILN based 100TPD DRI process
- Garikayi, T., Nyanga, L., Mushiri, T., Mhlanga, S., Kuipa, P.K.
- Authors: Garikayi, T. , Nyanga, L. , Mushiri, T. , Mhlanga, S. , Kuipa, P.K.
- Date: 2013
- Subjects: Sponge iron , Fuzzy logic , Kiln shell temperatures
- Type: Article
- Identifier: uj:4971 , http://hdl.handle.net/10210/13072
- Description: Sponge iron is an intermediate product of steel formed during direct reduction of iron ore with aid of regulated temperatures and pressures within a rotary kiln. The greatest challenge is the direct measurement of kiln shell temperatures due to the catastrophic accumulation of sintered particles of solid bed which form rings at places along the length of the kiln thus hindering material flow. The accretion reduces productivity, damage kiln lining and reduces the production period as well as reduction in product quality. This process requires a controller which will be able to control with imprecise and partial data input; and be able to achieve the desired product quality under dynamic process conditions thus a Fuzzy Controller was used for the proposed design. The main goal of the research was to predict the rate of accretion build up within the kiln and minimize it with aid of a Fuzzy Control System cascaded to an already existing Programmable Logic Controller. A 16.2% build up rate was achieved as compared to the most appreciated 27% thus nearly a 10% decrease, a result which can improve the campaign period by approximately 48 hours which will be a 200 tons of sponge iron.
- Full Text:
- Authors: Garikayi, T. , Nyanga, L. , Mushiri, T. , Mhlanga, S. , Kuipa, P.K.
- Date: 2013
- Subjects: Sponge iron , Fuzzy logic , Kiln shell temperatures
- Type: Article
- Identifier: uj:4971 , http://hdl.handle.net/10210/13072
- Description: Sponge iron is an intermediate product of steel formed during direct reduction of iron ore with aid of regulated temperatures and pressures within a rotary kiln. The greatest challenge is the direct measurement of kiln shell temperatures due to the catastrophic accumulation of sintered particles of solid bed which form rings at places along the length of the kiln thus hindering material flow. The accretion reduces productivity, damage kiln lining and reduces the production period as well as reduction in product quality. This process requires a controller which will be able to control with imprecise and partial data input; and be able to achieve the desired product quality under dynamic process conditions thus a Fuzzy Controller was used for the proposed design. The main goal of the research was to predict the rate of accretion build up within the kiln and minimize it with aid of a Fuzzy Control System cascaded to an already existing Programmable Logic Controller. A 16.2% build up rate was achieved as compared to the most appreciated 27% thus nearly a 10% decrease, a result which can improve the campaign period by approximately 48 hours which will be a 200 tons of sponge iron.
- Full Text:
Investigation of the effects of lubricant fat content on drawn copper wires
- Chiduwa, A.C., Nyanga, L., Mhlanga, S., Kanyemba, G., Van der Merwe, A.F.
- Authors: Chiduwa, A.C. , Nyanga, L. , Mhlanga, S. , Kanyemba, G. , Van der Merwe, A.F.
- Date: 2013
- Subjects: Cable manufacturing , Lubricant fat content , Lean manufacturing , Copper wire manufacturing
- Type: Article
- Identifier: uj:4963 , http://hdl.handle.net/10210/13064
- Description: The Lean Manufacturing goal of reducing waste and increasing productivity has made it a necessity to produce good quality products in manufacturing industries at a low cost. In the cable manufacturing companies this can be achieved by optimising the wire drawing process. One way to meet the desired quality of the drawn wires is to improve lubricant efficiency through installation of an automatic, continuous lubricant fat content control system on the drawing machine. The paper shows a method of finding the optimum lubricant concentration for producing good quality copper wires using Taguchi experiments. Taguchi experiments are employed to analyse the effects of different lubricant fat content levels on the tensile strength and lubricant temperature. The results from the experiments indicated that the tensile strength of the wire is affected by low lubricant fat content. The lower the lubricant fat content: the lower the tensile strength drawing lubricant resulting in numerous wire breakages that affect the quality of the final product, namely the cable.
- Full Text:
- Authors: Chiduwa, A.C. , Nyanga, L. , Mhlanga, S. , Kanyemba, G. , Van der Merwe, A.F.
- Date: 2013
- Subjects: Cable manufacturing , Lubricant fat content , Lean manufacturing , Copper wire manufacturing
- Type: Article
- Identifier: uj:4963 , http://hdl.handle.net/10210/13064
- Description: The Lean Manufacturing goal of reducing waste and increasing productivity has made it a necessity to produce good quality products in manufacturing industries at a low cost. In the cable manufacturing companies this can be achieved by optimising the wire drawing process. One way to meet the desired quality of the drawn wires is to improve lubricant efficiency through installation of an automatic, continuous lubricant fat content control system on the drawing machine. The paper shows a method of finding the optimum lubricant concentration for producing good quality copper wires using Taguchi experiments. Taguchi experiments are employed to analyse the effects of different lubricant fat content levels on the tensile strength and lubricant temperature. The results from the experiments indicated that the tensile strength of the wire is affected by low lubricant fat content. The lower the lubricant fat content: the lower the tensile strength drawing lubricant resulting in numerous wire breakages that affect the quality of the final product, namely the cable.
- Full Text:
Model reference adaptive control system for moisture regulation in cotton ginning
- Garikayi, T., Nyanga, L., Mushiri, T., Mhlanga, S., Muzinda, A., Mutangi, T.
- Authors: Garikayi, T. , Nyanga, L. , Mushiri, T. , Mhlanga, S. , Muzinda, A. , Mutangi, T.
- Date: 2013
- Subjects: Cotton ginning - Moisture control , Cotton - Moisture content , Model reference adaptive control
- Type: Article
- Identifier: uj:4928 , http://hdl.handle.net/10210/13028
- Description: Moisture content (mc) within the cotton fibre is an important aspect for all stages of the ginning process. However due to the process dynamics, mc is currently being controlled by regulating the water and air temperatures from the Humidifiers. Human intervention and lack of consistence on set-points determination has resulted in inconsistent mc during humidification. This procedure requires a control system which will be able to adjust the process set-points automatically by eliminating the need for human intervention. In this paper a robust Model Reference Adaptive Control (MRAC) system for a Samuel Jackson Humidifier is presented. This system improves upon the existing system by creating a closed loop controller with parameters that can be updated to change the response from reference model. The control parameters are then updated based on this error thus the parameters converge to ideal values that cause the plant response to match the response of the reference model.
- Full Text:
- Authors: Garikayi, T. , Nyanga, L. , Mushiri, T. , Mhlanga, S. , Muzinda, A. , Mutangi, T.
- Date: 2013
- Subjects: Cotton ginning - Moisture control , Cotton - Moisture content , Model reference adaptive control
- Type: Article
- Identifier: uj:4928 , http://hdl.handle.net/10210/13028
- Description: Moisture content (mc) within the cotton fibre is an important aspect for all stages of the ginning process. However due to the process dynamics, mc is currently being controlled by regulating the water and air temperatures from the Humidifiers. Human intervention and lack of consistence on set-points determination has resulted in inconsistent mc during humidification. This procedure requires a control system which will be able to adjust the process set-points automatically by eliminating the need for human intervention. In this paper a robust Model Reference Adaptive Control (MRAC) system for a Samuel Jackson Humidifier is presented. This system improves upon the existing system by creating a closed loop controller with parameters that can be updated to change the response from reference model. The control parameters are then updated based on this error thus the parameters converge to ideal values that cause the plant response to match the response of the reference model.
- Full Text:
Planning and monitoring tool to control profitability in a manufacturing concern : a case study at C Chemicals
- Mhlanga, S., Dlamini, W., Mbohwa, Charles, Pretorius, J. H. C.
- Authors: Mhlanga, S. , Dlamini, W. , Mbohwa, Charles , Pretorius, J. H. C.
- Date: 2011-09-21
- Subjects: Manufacturing industries , Production planning , Theory of constraints (Management) , Linear programming
- Type: Article
- Identifier: uj:5168 , http://hdl.handle.net/10210/14409
- Description: The aim of this paper is to analyse the key profit drivers in a manufacturing concern, and develop a decision tool based on optimisation techniques. The aim is planning and managing these profit drivers so that the target revenue and profit are realised during an operating period. This was done through developing a forecasting tool based on Visual Basic that was used by the organisation to project the future demand of its products. This tool was linked to a database that had details on past product performance. Planning software was developed using linear programming, which identified the optimum product mix and the sales outlets locations to maximise revenue and profit
- Full Text:
- Authors: Mhlanga, S. , Dlamini, W. , Mbohwa, Charles , Pretorius, J. H. C.
- Date: 2011-09-21
- Subjects: Manufacturing industries , Production planning , Theory of constraints (Management) , Linear programming
- Type: Article
- Identifier: uj:5168 , http://hdl.handle.net/10210/14409
- Description: The aim of this paper is to analyse the key profit drivers in a manufacturing concern, and develop a decision tool based on optimisation techniques. The aim is planning and managing these profit drivers so that the target revenue and profit are realised during an operating period. This was done through developing a forecasting tool based on Visual Basic that was used by the organisation to project the future demand of its products. This tool was linked to a database that had details on past product performance. Planning software was developed using linear programming, which identified the optimum product mix and the sales outlets locations to maximise revenue and profit
- Full Text:
System dynamics simulation for strategic green supply chain management
- Mutingi, M., Mbohwa, Charles, Mhlanga, S., Mapfaira, H.
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S. , Mapfaira, H.
- Date: 2013
- Subjects: Green supply chain management
- Type: Article
- Identifier: uj:4946 , http://hdl.handle.net/10210/13046
- Description: The design of appropriate green supply chains in the manufacturing sector is a crucial task. The present paper seeks to (i) identify suitable performance measures for green supply chains and to (ii) develop a dynamic simulation model to assist supply chain decision-makers in developing appropriate policies and strategies in green supply chain management. Based on the principles of the system dynamics methodology, causal linkages between internal and external factors affecting the development of green strategies are investigated. Green concepts are used to develop crucial environmental and eco-efficiency performance measures in regards to strategic green supply management. Results from what-if analysis indicate that proper implementation of green strategies produces significant improvements for environmental, economic/financial and operational performance. Further numerical experiments demonstrate that the model can provide sound managerial insights.
- Full Text:
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S. , Mapfaira, H.
- Date: 2013
- Subjects: Green supply chain management
- Type: Article
- Identifier: uj:4946 , http://hdl.handle.net/10210/13046
- Description: The design of appropriate green supply chains in the manufacturing sector is a crucial task. The present paper seeks to (i) identify suitable performance measures for green supply chains and to (ii) develop a dynamic simulation model to assist supply chain decision-makers in developing appropriate policies and strategies in green supply chain management. Based on the principles of the system dynamics methodology, causal linkages between internal and external factors affecting the development of green strategies are investigated. Green concepts are used to develop crucial environmental and eco-efficiency performance measures in regards to strategic green supply management. Results from what-if analysis indicate that proper implementation of green strategies produces significant improvements for environmental, economic/financial and operational performance. Further numerical experiments demonstrate that the model can provide sound managerial insights.
- Full Text:
- «
- ‹
- 1
- ›
- »