Jostle heuristics for the 2D-irregular shapes bin packing problems with free rotation

The paper investigates the two-dimensional irregular packing problem with multiple homogeneous bins (2DIBPP). The literature on irregular shaped packing problems is dominated by the single stock sheet strip packing problem. However, in reality manufacturers are cutting orders over multi-stock sheets. Despite its greater relevance, there are only a few papers that tackle this problem in the literature. A multi-stock sheet problem has two decision components; the allocation of pieces to stock sheets and the layout design for each stock sheet. In this paper, we propose a heuristic method that addresses both the allocation and placement problems together based on the Jostle algorithm. Jostle was first applied to strip packing. In order to apply Jostle to the bin packing problem we modify the placement heuristic. In addition we improve the search capability by introducing a diversification mechanism into the approach. Furthermore, the paper presents alternative strategies for handling rotation of pieces, which includes a restricted set of angles and unrestricted rotation. Very few authors permit unrestricted rotation of pieces, despite this being a feature of many problems where the material is homogeneous. Finally, we investigate alternative placement criteria and show that the most commonly applied bottom left criteria does not perform as well as other options. The paper evaluates performance of each algorithm using different sets of instances considering convex and non-convex shapes. Findings of this study reveal that the proposed algorithms can be applied to different variants of the problem and generate significantly better results

Application of genetic algorithm to optimize cut-order planning solutions in apparel industry

The fabric cutting process acts as the second major cost contributor of the apparel manufacturing process due to the high expenditure on marker making, fabric spreading and cutting, which is about 5-10% of the total manufacturing cost. Researchers highlight that an effective cut order plan results in reducing the abovementioned cost factors of cutting process, thereby reducing the entire manufacturing cost, to a greater extent. This study aims on optimizing the cut order plan solutions using Genetic Algorithm (GA) principles. Optimization algorithm was proposed based on GA principles and the computer-based program was introduced to execute the algorithm, under MATLAB environment. The performance of proposed algorithm was then compared with respect to the available methodologies of generating cut-order plans available in Sri Lankan Apparel industry

Regression model to predict thread consumption incorporating thread-tension constraint : study on lock-stitch 301 and chain-stitch 401

Prediction of sewing thread consumption requires an accurate method of calculation since it relates to the cost of manufacturing and distribution of apparel products. Previous researchers highlighted problems in existing thread consumption calculation methods; i.e. limitations in existing formulae which cause inaccurate predictions of thread amount needed for sewing operations. The existing methods of consumption calculations exhibit significant error percentages due to the ignorance of important parameters which affect on thread consumption. This paper investigates on correlation of thread tension to thread consumption of lock-stitch 301 and chain-stitch 401. The existing thread consumption formulae are optimized by considering a new parameter; thread tension, using regression analysis and geometrical modeling techniques. For the chain-stitch 401, results indicate that the thread tension significantly affects in determination of the thread consumption. The error analysis of proposed formulae was performed to indicate that the proposed formulae more accurate compared to the available methods of predicting sewing thread consumption. In addition, there are combined effects of thread tensions together with parameters such as fabric thickness and stitch density which determines accurate consumption values considering the properties of the stitch. In comparison, inclusion of the proposed thread tension variable depicts reduction in error percentages, so that the proposed formulae are expected to be a better approach to calculate thread consumption of lock-stitch 301 and chain-stitch 401

Industry 4.0 elements and analytics for garment assembly production lines

The world is now witnessing the 4th industrial revolution technology and this is commonly known as Industry 4.0. This study focuses on developing a prototype to demonstrate the smart production line by using Industry 4.0 elements for apparel manufacturing which captures the cycle times of garment assembly operations and balance workloads. As the key elements. Internet of Things (IoT), Cloud Computing and Big data were involved to convert a traditional assembly line to a smart assembly line. The developed prototype allows to capture cycle times of operations and sends those data to a cloud through a wireless network. The data stored in the cloud compute the required arithmetic to draw Yamazumi work balance chart which is dynamically updated without human intervention. A computer client application attached to the cloud act as a decision support system which helps production management to make decisions efficiently. As the special features, the proposed system is also compatible with walking worker production lines where operators are moving from one workstation to another, which also captures actual utilization of the worker at different workstations along the production line which is harder to capture accurately in the actual production scenario

Addressing post-consumer textile waste in developing economies

Consumer attitudes and disposal behaviour of textiles in developing economies are under researched, constraining capacity to address dual environmental challenges of increasingly disposable fashion and inefficient waste collection programs. We present the results of a systematic case study about post-consumer textiles waste in Colombo, Sri Lanka. Taking post-consumer textile waste as our unit of analysis, we conducted in-depth and semi-structured interviews with the local industry stakeholders, the waste management infrastructure and an island-wide survey of consumer attitudes and disposal behaviour towards post-consumer textile waste. The results indicate: (a) considerably more post-consumer textile waste than recorded at landfills; (b) consumption and disposal behaviour comparable with developed economies, significant in contexts of no formal mechanisms to address end of life post-consumer textile waste and (c) age, employment category, income level and geographical location, are statistically significant in understanding public textile waste disposal behaviour, indicating importance of appropriate policy and infrastructure issues

Development of a comprehensive fabric quality grading system for selected end uses

This study focuses on the development of a comprehensive fabric quality grading system for selected end uses. This system goes beyond currently existing methods by reflecting the suitability of a candidate fabric for a specific end use, by evaluating its key properties and grading the fabric with respect to its overall quality level and has been developed by studying the retailer fabric specification standards. A set of fabric parameters was selected for each of four retailer customers who were identified by an industrial survey. The selected fabric parameters were transformed into a sub-index value calculated by an equation for each parameter using test values obtained from the considered fabric. Weights were assigned to the parameters considering the level of importance identified by the survey for each fabric parameter. A weighted arithmetic mean function was used as the aggregation function in which the aggregate of the products of sub index value and the weighting for each arameter were taken as the overall fabric quality value on a scale of zero to hundred. This system is designed to assist decision makers in selecting a suitable fabric material for a specific end use by comparing the overall quality of several fabrics. A computer application was developed as the user interface to evaluate fabrics using the developed system. The results obtained from this system compared favourably with those obtained through manual evaluation of the fabri