Monday, February 3, 2020

Iris Publishers-Open access Journal of Textile Science & Fashion Technology| Improvement of Efficiency and Productivity Through Machine Balancing in a Sewing Line




Authored by Champa Saha


Introduction

The ready-made garment (RMG) sector is the life-blood of Bangladesh economy achieving higher export growth every year. The sector is now the largest contributor not only to overseas trade but also to the national economy. Today’s business climate for clothing manufacturers requires low inventory and quick response systems that turn out a wide variety of products to meet customers demand [1]. It is especially in the Apparel industry that managers are trying to develop their current systems or looking for new production techniques in order to keep pace with the rapid charges in the fashion industry. Therefore, to develop a new system, good observations needed. However, to observe real manufacturing systems is very expensive and sometimes cumbersome [2]. The rapid rate at which the whole process takes place, the interaction between workers and the different transition times between workers make it increasingly more difficult for a human being to make correct decisions regarding how fast each operator should work in order to continue the process, while at the same time keeping productivity high and throughput at an acceptable level [3]. Construction of a quality garment requires a great deal of knowhow, a lot of coordination and schedule management. Clothing manufacturing consists of a variety of product categories materials and styling. dealing with constantly changing styles and consumer demands is so difficult. Furthermore, to adapt automation for the clothing system is also so hard because, beside the complex structure also it is labor intensive. There-fore, garment production needs properly rationalized manufacturing technology, management and planning [4]. In garment production, until garment components are gathered into a finished garment, they are assembled through a subassembly process. The production process includes a set of workstations, at each of which a specific task is carried out in a restricted sequence, with hundreds of employees and thousands of bundles of sub-assemblies producing different styles simultaneously [5]. The joining together of components, known as the sewing process, which is the most labor-intensive part of garment manufacturing, makes the structure complex as some works has a priority before being assembled [6]. Furthermore, since sewing process is labor intensive; apart from material costs, the cost structure of the sewing process is also important. Therefore, this process is of critical importance and needs to be planned more carefully [7]. As a consequence, good line balancing with small stocks in the sewing line has to be drawn up to increase the efficiency and quality of production. An assembly line is defined as a set of distinct tasks which is assigned to a set of workstations linked together by a transport mechanism under detailed assembling sequences specifying how the assembling process flows from one station to another. In assembly line balancing, allocation of jobs to ma-chines is based on the objective of minimizing the workflow among the operators, reducing the throughput time as well as the work in progress and thus increasing productivity. Sharing a job of work between several people is called division of labor. Division of labor should be balanced equally by ensuring the time spent at each station approximately the same. Each individual step in the assembly of product has to be analyzed carefully and allocated to stations in a balanced way never the available workstations. Each operator then carries out operations properly and the work flow is synchronized. In a detailed work flow, synchronized link includes short distances between stations, low volume of work in process, precise o planning of production times and predictable production quantity [8]. Overall, the important criteria in garment production is whether assembly work will be finished on time for delivery, how machines and employees are being utilized, whether any station in the assembly line is lagging behind the schedule and how the assembly line is doing overall [9,10]. To achieve this approach, work-time study, assembly line balancing and simulation can be applied to apparel production line to find alternative solutions to increase the efficiency of the sewing line [11]. Factories in Srilanka and India operate at 80% - 90% of efficiency, whereas in Bangladesh according to some experts, productivity is between 35- 55% of efficiency with very few exceptions. For the RMG sector in Bangladesh productivity alone can make a difference between life and death [12].

Productivity

In simple words, productivity is the relationship between output and input. The output in garments factories can be pieces of finished garments. The output of sections or departments within the garment factories could be, meters of the fabric inspected in fabric inspection section cut components in cutting room, number of garments ironed in the ironing section and so on. The examples of input are – man hours, machine hours, and meters of fabric consumed, or electricity consumed [13].

Clarification

In simple words, productivity is concerned with the efficient utilization of resources (inputs) in producing goods. This expression may also be called ‘productive efficiency.
Factor Productivity (Labor)=Output/Input(Labor)

Line balancing

The Line Balancing is to design a smooth production flowed by allotting processes to workers so as to allow each worker to complete the allotted workload within an even time. Line balancing is an effective tool to improve the throughput of assembly lines and work cells while reducing manpower requirements and costs. Assembly Line Balancing, or simply Line Balancing (LB) is the problem of as-signing operations to workstations along an assembly line, in such a way that the assignment be optimal in some sense. Ever since Henry Ford’s introduction of assembly lines, LB has been an optimization problem of significant industrial importance, the efficiency difference between an optimal and a sub-optimal assignment can yield economies (or waste) reaching millions of dollars per year. It is a system where we meet the production expectations and we can find the same amount of work in process in every operation at any point in the day.

Reasons for machine balancing

Purpose of balancing a line is to reduce operator’s idle time or maximize operator utilization. In a balanced line work will flow smoothly and no time will be lost in waiting for work. A time of line setting select operators for the operation matching operator skill history and skill required. Following this method, we will select highly skilled operators for higher work content operations. Once line is set conduct capacity study at a regular interval. We have to use pitch diagram method to find bottlenecks inside the line. We have to think how we will minimize WIP level at bottleneck operations.
• Keeping inventory costs low results in higher net income.
• Keeping normal inventory levels lets the operator work all day long giving him/her the opportunity to earn more money by increasing his/her efficiency.
• Keeping the line balanced lets the supervisors improve other areas because they can use their time better.
• Balanced production keeps prices low which turns into repeat sales.
• Balanced production means better production planning.

Materials and Methods

Required tools and materials

Different materials and methods are mainly used based on the work Experiments. Here, the following materials and tools are used to complete the testing and evaluation of this work:
• Stop Watch
• Spread Sheet
• Calculator
• Paper and Pencils

Equations

irispublishers-openaccess-textile-science-fashion irispublishers-openaccess-textile-science-fashion

Data analysis and calculation

Before balancing line: Table 1 shows that the target per hour for the line calculating total 37 manpower worked on that line for 600 minutes with a S.A.M value of 8.90. We have standardized the Bench mark target of 200 pieces of garment at 80% efficiency. Observation before balancing the line has been reflected as labor and machine productivity is 30 and 50, line efficiency is 44%.


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