Carbon Emission Evaluation Based on Multi-Objective Balance of Sewing Assembly Line in Apparel Industry

Abstract

Apparel manufacturing is an industry with high energy consumption and carbon emissions. With the development of the low-carbon economy, low-carbon production in the apparel manufacturing industry become more and more imperative. The apparel industry is encountering great challenges in reducing carbon emissions. Garment sewing comprises a large number of processes, machines and operators. However, the existing studies lack quantitative analysis of carbon sources in the sewing process. This study analyzed the carbon emission characteristics in garment sewing production. Evaluation models of carbon emission were established for the sewing process in this research and the factors of fabrics, accessories, sewing machines and operators were included in the models. The results showed that fabrics and accessories were the main sources of carbon emissions in garment sewing production. The second largest carbon emission source was sewing machines, followed by operators. According to the evaluation models, the number of machines, operators and the utilization rate of the machines were related to the balance of the assembly line. A multi-objective optimization model aimed at minimizing the time loss rate and smoothness index of the assembly line was established, and a fast and elitist multi-objective genetic algorithm was used to obtain the solution for carbon emission reduction. The men’s shirt assembly lines, based on three types of workstation layouts (the order of processes, the type of machines and the components of the garment), were applied to verify the effectiveness of the model and algorithm. The results indicated that the total carbon emissions of the three assembly lines based on balance optimization were less than that of the normal assembly line. The assembly line of the workstations arranged in the order of processes was the best assembly line since it had the highest efficiency and the lowest carbon emissions.

Taking climate action

“…Studies focused on particular factories, brands or garments also found similar results. For example, a 2019 study of a sewing assembly line for men's shirts in China found that fabrics are the main source of carbon emissions (Zhang and Chen 2019). Another study from China on the impacts of a cotton T shirt production also found that the largest contributors to carbon emissions in the life cycle was the dyeing process (35 per cent); however, this study also found significant emissions in the garment assembly stage (32 per cent) (Zhang et al 2015).…”

“…In China, the largest global producer of textiles and garments, the apparel industry is the sixth-largest industry sector in terms of energy consumption (Zhang and Chen 2019). In Bangladesh, the textile and garments industry is the top export earner, generating 81 per cent of gross domestic income.…”

A complex garment assembly line balancing using simulation‐based optimization

“…39 The applied line balancing problems in garment manufacturing evolved because garment assembly line poses unique balancing problems to those of large body assembly lines such as trucks, buses, aircraft, and machines. 40,41 In most studies, garment assembly line balancing has been implemented using several techniques including ranked positional weight, 42 COMSOAL, 43 largest candidate rule, 44 and simulation. 41 As the complexity of garment assembly line increases depending on the fashion styles, most of these methods become less effective and inferior for line balancing .…”

“…The NYTIL trouser assembly line right hip pocket (20)(21)(22)(23)(24), knee pocket preparation (KPP) for making both left and right knee pocket (32)(33)(34)(35)(36), knee flap preparation (KFP) for making both left and right knee flap (38)(39)(40)(41)(42), big loop preparation (BLP) for making seven big loops per trouser (47)(48)(49)(50)(51), small loop preparation (SLP) for stitching small loops and cutting into seven pieces required per trouser (52), adjustable rope preparation (ARP) for cutting and attaching two sets of adjustable rope at two positions on trouser waist band (65)(66), and main body assembly (MBA) for assembling all the prepared parts and other parts (do not require preparation) to the trouser body and involves other operations such as trimming, turning, quality checking, and…”

“…Therefore, applied line balancing problems which has been derived from GABLP are most suitable for such systems 39 . The applied line balancing problems in garment manufacturing evolved because garment assembly line poses unique balancing problems to those of large body assembly lines such as trucks, buses, aircraft, and machines 40,41 …”