Master of Philosophy (M.Phil.)

Permanent URI for this collectionhttp://192.248.9.226/handle/123/18728

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Now showing 1 - 7 of 7

item: Thesis-Abstract
Investigation of suitable methods to extract the fibres and optimization of treatment methods for sri lankan banana cultivars for textile material
(2021) Balakrishnan S; Wickramasinghe GLD; Wijayapala UGS
The banana pseudostem is an ideal source of natural cellulose substitute fibre. This thesis investigates the effects of banana fibre extraction and treatment parameters on fibre fineness, and establishes suitable methods to reduce the fineness that enable the usage of banana fibres as textile materials. Ten popular Sri Lankan varieties of banana pseudostem were selected for this study. Among the fibre fineness of the mechanically extracted banana fibre of the ten varieties, Ambun (genome AAA) middle layers of the pesudostem was selected for further analysis since it gives the lowest fineness. Enzyme and chemical treatments was ministered to the mechanically extracted fibre of the middle layers of the pseudostem. The diameter of the scanning electron microscope and fibre linear density were used to observe and determine the fineness of the biologically and chemically extracted fibres and enzymes from the chemically treated banana fibres. This demonstrated that fibres treated with a combination of enzymes and chemicals to be the finest. Furthermore, it was discovered that due to this combined treatment of enzymes and chemicals (5% Enzyme and 6% H2O2, 2% Na2SiO3, 3% NaOH) treated banana fibres achieved fibre linear density of 4 tex. The diameter of the fibre was reduced from 168.4μm to 48.8μm, which is a 71% reduction compared to the diameter of the mechanically extracted fibre. All the experiments conducted on the reflectance curves of dyed banana fibres found that the dye absorption tendency of pre-treated banana fibres and it’s dyeing behaviours to be similar to that of cotton. This leads the current study to posit that the process of dyeing cotton can be used to dye banana fibres as well. The outcome of this research is to help those working in the apparel industry to select Sri Lankan banana fibres based on strength and finesse suitable for their textile products.
item: Thesis-Full-text
Analyzing the thermal shrinkage behavior of polyester / elastomeric weft knitted fabrics
(2020) Perera, HAAE; Lanarolle, WDG
Thermoplastic polymer fabrics are normally heat set to make them dimensionally stable. These fabrics in garment panel form may again be exposed to heat during the processes such as rubber print curing and cause to change their dimensions. The key issue addressed in this study; the thermal shrinkage of heat-set polyester/elastomeric knitted fabrics during postheat treatment processes which is a practical and a current problem in the garment industry. The thermal shrinkage behavior of heat-set polyester knitted fabrics, under a wide range of conditions, mainly to simulate the post-heat treatment processes, using geometric and thermodynamic parameters were investigated. The findings present a statistically sound analysis of different thermal behavior patterns, while examining their causes based on both material properties and dimensions of the plain knitted fabrics. The key findings reveal that heat-setting and heat-curing temperatures have a significant effect on thermal shrinkage behavior. Thermal shrinkage in course direction is highly related to the width-wise extension applied during heat-setting and the wale direction is highly correlated to the shrinkage behavior of the yarns in hank form. Noticeable changes in polyester thermal behavior occur at 160°C and thermal shrinkage is heavily influenced by thermal history of materials. Taut-end and slack-end conditions maintained while heatsetting and heat-curing significantly affected thermal shrinkage. The higher percentage of overfeed during heat-setting leads to lower thermal shrinkages in subsequent thermal activities. Thermal shrinkage was evidence of a change in the structural parameters of knitted material. Structural changes are mainly due to the change of shape of the loop and/or thermal shrinkage of the stitch length. The introduction of elastomeric yarn to the polyester knitted structure led to make more thermally stable fabrics. In order to reduce thermal shrinkage during subsequent heat treatment, a high temperature heat-setting and a moderate percentage over feed should be retained during thermal setting. The post heat treatment results revealed that the low temperatures during heat treatments though have no trend but causes comparatively low thermal shrinkage or expansion, it is safe and advisable to use low post heat setting temperatures where possible.
item: Thesis-Full-text
Development of a customizable production line layout planning system for Sri Lankan fast fashion apparel industry
Perera, KGU; Kulatunga, AK
Fast fashion apparel industry is having a significant growth in international markets. Frequent fluctuation of customer demand with smaller batch quantities and, short lead-times, are the key characteristics of fast fashion apparel products. Main target markets of Sri Lankan ready-made apparel industry are rapidly adapting the fast fashion strategy. In order to retain and attract the customers of Sri Lankan ready-made apparel industry, it is essential to address the frequent problems related with fast fashion apparels. This research addresses the increased changeover cost related with production line layouts, which is the major problem in terms of fast fashion apparels. The developed production layout planning system uses dynamic cellular manufacturing concept as the basis. A comprehensive literature review, case study on a selected factory, and questionnaires were used to determine the essential features included in the developed system. The developed system consists of two mathematical models, an algorithm and a computer program to determine the optimum layout solutions that minimize the costs of machine set-ups, machine relocations, material handling, and workload balancing. The developed system is validated using case studies conducted in five apparel manufacturing factories that are currently producing fast fashion apparels. According to the validation results, the developed system is capable of achieving significant cost saving percentages compared to current state in the selected factories.
item: Thesis-Abstract
Framework to implement business process management principles in apparel manufacturing
(2016-02-12) Yapa, TSD
The Sri Lankan Apparel Industry at present is in the forefront in adapting current methodologies in relation to process improvement. Many organizations have successfully implemented lean concepts, six sigma methodologies and various other philosophies. However, it appears that the implementation of such tools and techniques have often been done in specific areas without taking a holistic view into consideration. Business Process Management (BPM) is an emerging powerful concept which proposes a holistic approach for business process improvement. This research focuses on guiding the implementation of BPM principles to the Sri Lankan Apparel Industry. It targets on three BPM concepts; process orientation, performance improvement and structured approach. The BPM implementation framework proposed by the study executes in three phases where each phase guides in implementing at least one of those principles. Comprehensive literature review followed by industry surveys assist in developing the proposed framework. The proposed framework offers direction to the Sri Lankan apparel manufacturing organizations in transforming the business from functions to processes. The framework further delivers a set of performance improvement best practices suitable for the Sri Lankan Apparel Industry while presenting a lifecycle to follow, when implementing them. The proposed lifecycle encompasses a set of techniques which can be used in executing each step of the lifecycle. The BPM maturity measuring framework embedded with the BPM implementation framework acts as an assessment tool in evaluating the level of BPM maturity that organizations have achieved after the implementation of BPM initiatives. The validation survey proved the effectiveness of the proposed framework against the existing industry approaches in improving and managing business processes, in terms of accuracy, adaptability and performance. The proposed framework focuses on delivering methodical guidance about how process improvement and management efforts should be done, by taking Business Process Management principles into consideration.
item: Thesis-Abstract
Design of a computer system for the analysis of defects and grading of woven fabrics
(6/23/2011) Niles, SN; Fernando, S; Lanerolle, WDG
Inspection of fabrics is a major consideration in fabric manufacture, as well as in the manufacture of garments and other fabric-based goods. In the Sri Lankan industry fabric inspection is almost entirely carried out by manual methods, and is therefore subjective and prone to human error. This research has sought to address this problem by developing a computerised system to analyse and grade fabrics on the basis of captured defective images obtained from the fabric. In this research a computer-based system for the objective assessment of fabric defects was designed. The system was designed with special emphasis on the fabric defects occurring in the Sri Lankan industry. Image processing techniques were used to analyse scanned images of the test fabric, compare it with an ideal sample which is made available, and identify defects according to pre-learnt rules. The information gathered was then used to grade the fabric, either by giving the frequency of occurrence of defects or by assigning points. A new classification method for common defects was designed, that would facilitate easy grading according to commonly used grading systems. A coding system for defects was also designed, which helps in reporting defects to the user. The detected fabric defects were classified and stored according to the developed classification method and using the proposed coding system.
item: Thesis-Abstract
Positive environmental management via waste minimisation in a textile washing factory
(6/11/2011) Wijayapala, S; De Alwis, A; De Silva, NGH
Textile and garment Industry is an important industry sector in the Sri Lankan economy. The finishing part comprises the final step in textile processing and it is known as a sector with high polluting potential. In the textile washing sector considerable quantities of water is used only once usually and is discharged without any recovery. To stay competitive this industry needs to be modernized and definitely needs better performance in the environmental management sector. This project was limited to looking at the environmental management aspects and that too with only a single pollutant stream -water. The sector of the textile industry considered is the textile washing industry. A garment washing plant is analyzed with the objective of promoting water recycling and waste minimization practices. Initially typical practices were reported, followed by a water balance for the system . Results of the water audit presented here forms the first essential element of the waste minimization process. Water stream is considered from the inlet to the exit, and the consideration is given to methods of conservation possible of this valuable natural resource while obtaining the optimal use in the process. The time that water was assumed to be a limitless low-cost resource has already passed. Today there is an increasing awareness of the danger to the environment caused by over-extraction and use of water. There is now considerable incentive to reduce both consumption and waste water production. The selection of the washing industry was selected for this study under that consideration. This industry sector today uses significant quantities of water and most of the factories neither utilize waste minimization nor water recycling techniques. The waste treatment methods are also not adequate. Thus there is a tremendous potential on savings on one hand and a need on the other hand. It was shown that it is feasible to utilize groundwater after treatment. Manganese is not appearing to be a major problem. The problem chemical appears to be the presence of iron. Iron can be removed from groundwater using several operations. This eliminates the transport of water from outside and serves many environmental needs such as reduced traffic, removing reliance on outside sources and events etc. A pilot plant was constructed in the laboratory and four methods of iron removal were analyzed. Ozonation was studied as a method of reducing this wastage. In this manner there would be a reduced demand on the freshwater resource as well as reduced discharge of effluents. Thus the situation would lead to a facility whereby the waste minimization has taken place and a facility with positive environmental management. It has been shown that this technology offers many advantages to the industry including the recycling option. Ozonation in addition provided abilities to provide the required input quality as well in addition to being able to reduce COD, BOD and the most importantly Color of effluents. It was seen that processes are carried out with less attention being paid to the overall efficiencies but only towards meeting production targets and/or meeting deadlines. The feasibility of recycling waste water was shown. The practice of this would be a major improvement on the current environmental performance.
item: Thesis-Abstract
Performance improvement in apparel manufacturing using lean techniques
(7/22/2011) Ratnayake RMVS
The labour productivity in the Sri Lankan garment industry is found to be rather low compared to that of some of its competitive countries. On site investigation revealed that the workflow gets unbalanced due to many reasons despite it i balanced at the commencement of a new style. The Work In Progress (WIP) and its fluctuation are found as two apparent factors reducing the labour productivity in addition to disorganized set-up activities during style changes. The significance of the problem of high WIP and its high fluctuation are investigated through the data collected from 42 garment manufacturing lines in 14 different factories. Hypothesis testing on these data revealed that this is a common problem across all 14 factories under this study. Root cause analysis on WIP fluctuation disclosed the major contributing factors to the problem. Identifying each sewing line in few 'sub-cells" where a team of operators focuses mainly on one part of the garment helped addressing most of the problems identified in the root cause analysis. An algorithm to balance the production line and the sub-cells is devised. The concept was successfully implemented in a garment manufacturing company in Sri Lanka. The evaluation of the performance indicators revealed that the production efficiency has increased by more than 10% while drasticatly reducing the defect percentage. The operator absenteeism too has significantly reduced. This may be due to the fact that the operators' motivation to work and their income are increased as disclosed by the results of the questionnaire survey among operators and the supervisors. High, but inevitable, style changes aggravate the problem of low labour productivity as drastic production efficiency drops are experienced during the changeover. The quick changeovers concepts commonly found in lean manufacturing and newly proposed five step set-up procedure streamlined the set-up activities. The implementation of the proposed set-up procedure made it possible to increase the average first day production efficiency of the factory over 80% and a significant reduction in the set-up times as compared with the statistics before implementation.

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