Applied Mechanics and Materials Vols. 110-116

Abstract: —In this paper, a conceptual framework to apply many techniques for implementing lean in the high-variety low-volume (HVLV) environment is presented. Lean production has increasingly being implemented as a potential solution for many organizations. Anyway, the lean formula is applicable directly only to the make-to-stock business, but the make-to-order (MTO) product environment has to adapt lean manufacturing principle. The method of this paper has a two-phase quantitative framework to transform small and medium enterprises (SMEs) to be lean. Phase 1 has three interrelated components: (1) re-engineering an organization by using the power of computer simulation combined with business process. (2) Value stream mapping (VSM) is used to create a map of both value and waste in a given process. This tool has also a main drawback for job shop facility because many value streams are composed of hundreds of industrial parts and products. (3) Integrative supplier relationship is one of the most critical factors to maintain an advantage in the increasing levels of competition. Phase 2 performs a just in time production schedule by using ant colony optimization technique combines with a simulation tool. The aims of this paper are to develop a suitable lean manufacturing system for SMEs and to study the performance of the system for improving effectiveness. The result shows how to combine lean concept with simulation optimization, the step of this framework to obtain the optimization solution.

Abstract: The main objective of the project was to investigate the influence of the selected priority rules of technological operations on chosen production goals. The paper presents the results of the project. The dynamic scheduling process of operations was simulated on the model of production system. The effect of each priority rule has been studied for different production goals in different stressful situations. The synthesis and the evaluation of results were performed by using mathematical and statistical methods. The multi-objective evaluations scoring method have been chosen by authors.

Abstract: Lean Manufacturing can be considered as a business strategy which was originated and developed in Japan. It tries to identify waste and eliminate it. Thus it leads to improvement in productivity and quality and companies can achieve a competitive advantage over others. Sri Lankan industries, especially apparel sector have attempted to implement this, but a little research work is carried out in regarding its suitability. This research is an attempt to identify a suitable Lean model for the apparel industry in Sri Lanka. As the initial stage of this study, a literature review is carried out to study about the Lean Manufacturing. It starts by looking at how Lean Manufacturing first began. Then it seeks to identify the core principles, tools and techniques and how those tools and techniques are currently being used worldwide. After studying the global scenario the next step is to look at the Sri Lankan context using real world data. This was undertaken by means of structured surveys, observations, and on site interviews. Also the study will reveal period of Lean implementation, suitable implementation methods, order of implementation, tools which are avoided, sustainability of different tools, challenges faced, ways of overcoming challenges and benefits achieved after applying Lean Manufacturing concepts in the apparel sector of Sri Lanka. The findings state Lean Manufacturing can be applied to mass production apparel industries and has created a positive mindset on employees. As implementation of Lean concepts is still in developmental stage, the full benefit is not yet achieved. But current situation suggests that the industry can go forward with Lean and capitalize on its full potential. In this research the authors have proposed a model which can be used to implement Lean in a systematic manner and each manufacturer must develop their own Lean system through training, experiments, employee empowerment, right leadership and kaizen mindset. Originality of the research— The research builds up a Lean Model which is not yet developed for the apparel sector in Sri Lanka. It can be further modified to suit the global apparel industry and other industries as well.

Abstract: Quality control and improvement at the process level is a vital activity for the achievement of defect-free products in various manufacturing processes. This study employs statistical process control (SPC) tools such as control charts and process capability ratio for quality control and improvement. The control charts employed are , R and the cumulative-sum (CUSUM). The process capability ratio used is the so called process capability index (PCI). These tools have been implemented with the aid of Minitab® statistical software. In this study, the manufacturing process of gelatin capsules is investigated in terms of quality of the capsules, which are produced and shipped for use by various drug companies. As a result of implementation of SPC tools, an expected reduction in the number of defective capsules by 29% relative to the stage before implementation was achieved.

Abstract: The PAF model, which is one of techniques about the cost of quality (CoQ), has been introduced to the head stack assembly process in the hard disk drive industry. Purpose to measure the total CoQ in the current process and use it as a tool to identify problems related to quality costs in order to find improvement plans. The total CoQ has been calculated in the percentage of the cost of quality per the cost of finished goods. Cost elements that impacted to the total CoQ have been prioritized and analyzed by using the Fish Bone diagram and the FMEA tool to find the potential causes of problems. The improvement plans have been implemented in order to reduce the chance of occurrences and improve detection ability. The result on two head stack models showed that the total CoQ could be reduced from 1.45% to 1.36% or 6.21% of improvement on the model A and reduced from 1.11% to 1.08% or 2.70% of improvement on the model B. The optimum points between the total CoQ and the quality level are 1.32% and 99.32% on the model A and 1.07% and 98.95% on the model B.

Abstract: A new methodology has been proposed to optimize both the planning of preventive maintenance and the time required to perform maintenance in a process plant is presented. In the Plant Maintenance process there is an increased need to make the shop floor layout more easily reachable user pliable. This allows Plant Maintenance staff to focus more on minimizing downtime and increasing productivity. Being more mobile allows them to go from more reactive maintenance to proactive maintenance. In this paper a single facility location problem with multiple relocation opportunities is investigated. The weight associated with each demand point is a known function of distance and time. We consider either rectilinear, or squared Euclidean, or Euclidean distances. The objective function is to minimize the total travelling distance from service center to various machines locations,thereby reducing the total maintenance time.

Abstract: Most of existing frameworks for modeling and simulation of hybrid systems represent continuous behavior of systems using ordinary differential equations (ODEs). ODE models can be represented as discrete event system specification (DEVS) models through discretization and simulated in the DEVS simulation framework. However, in cyber-physical systems (CPS), it is difficult to represent the continuous behavior of a system using an ODE because it can have unknown, unpredictable variables. In that case, it is needed to predict the model’s next event time by inference to embed the model in a DEVS model. We propose the simulation framework in which a fuzzy inference module is added to each simulation model to determine its next event time. The proposed method enables simulation of hybrid system models which can or cannot be represented using an ODE.

Abstract: Lean Manufacturing has been widely adopted in various business and industries worldwide. To determine the current stage of Lean implementation in Thailand and the barrier Lean implementation, the qualitative research involving interview with 10 industrial companies practicing Lean manufacturing was conducted. The result from this study shows that most Lean practitioners understand the principal of Lean manufacturing. Different organization functions adopt different types of Lean tools and techniques as well as the performance measures depending on their business characteristics. However, there are three performance measures, which are manufacturing cost per unit, total sales and part per million (PPM) in defective products shipped to customers, that were adopted by all 10 companies. The most important barrier in Lean implementation is the cultural change since it requires the entire company participation. Finally, the companies participated in this study confirmed that they are satisfy with the result of Lean manufacturing though some companies have not completely adopted the Lean approach into their manufacturing process. To excellent the Lean manufacturing, companies are required to satisfy customer needs, improve the manufacturing process, and increase their flexibility. Furthermore, it is necessary for the top management to provide a clear policies as well as plan and direction. If Lean implementation is to be successful, the communication and human resource department are also the main keys.

Abstract: Lean production, which is regarded as the third production mode after craft-ship and mass production mode, now is being applied widely by more and more enterprises. Toyota Motor Corporation as well as many other enterprises’s success has proved that lean production is one of the most scientific and advanced production models in the world. In order to upgrade management level and decrease technology gap with foreign enterprises, the enterprises of our country began to contact and learn lean production at the late of 1970s, but till now the relative study is far behind compared with that of western country. This situation has impeded the application and development of lean production in China. Pointed to this situation, this paper does application appraisal of lean production using data get by questionnaire. In the process of appraisal, data envelopment analysis is used to do analysis from the angle of relative efficiency. This method can weaken the impaction of enterprise’s scale and its development stage as well as other factors so the appraisal result will be more objective and impartial. In order to get reasonable and scientific analysis result, this paper does study using not only financial performance index but also non financial index, because traditional financial indexes cannot cover the traits of lean production. The quantitative anlysis result shows that lean production’s implementation has profound influence to upgrade enterprises’ relative efficiency.

Abstract: This paper investigates permutation flow shop scheduling problems with sequence-dependent setup times with minimizing the number of tardy jobs as criterion (F_m|prmu, S_ijk|∑U_j). Since the proposed research problem has been proven to be NP-hard, three different meta heuristic algorithms based on tabu search (TS) has been proposed to solve the problem. These three algorithms are different based on their tabu list characteristics. In order to evaluate the performance of the proposed TS algorithms, test problems in different ranges are generated to find the best algorithm. The comparison shows that the TS algorithm which its tabu list keeps track of the slots that the jobs are assigned has a better performance than the other algorithms