Cross-trained worker assignment and comparative analysis on throughput of divisional and rotating seru

DOIhttps://doi.org/10.1108/IMDS-07-2017-0303
Pages1114-1136
Publication Date11 Jun 2018
AuthorLang Wu,Felix T.S. Chan,Ben Niu,Li Li
subjectMatterInformation & knowledge management,Information systems,Data management systems,Knowledge management,Knowledge sharing,Management science & operations,Supply chain management,Supply chain information systems,Logistics,Quality management/systems
Cross-trained worker assignment
and comparative analysis on
throughput of divisional and
rotating seru
Lang Wu
College of Management, Shenzhen University, Shenzhen, China
Felix T.S. Chan
Department of Industrial and Systems Engineering,
The Hong Kong Polytechnic University, Hung Hom, Hong Kong
Ben Niu
Shenzhen University, Shenzhen, China and
Department of Industrial and Systems Engineering,
The Hong Kong Polytechnic University, Hung Hom, Hong Kong, and
Li Li
Shenzhen University, Shenzhen, China
Abstract
Purpose Seru (cell) manufacturing system has achieved huge success in production. However, related
research is limited, especially, the problem of cross-trained worker assignment. The purpose of this paper is to
solve this problem for two representative seru types, divisional and rotating seru, and subsequently, compare
throughput performance between the two seru types under reasonable worker-task assignment.
Design/methodology/approach For the cross-trained worker assignment problem, this research
presents new models aiming at maximum throughput of seru and workload balance of workers under
considering skill levels (SLs) and several practical constraints. Furthermore, factorial experiments that
involve four factors, the number of tasks (NT), gap of task time, SL and gap of SL, are performed to compare
throughput performance between divisional and rotating seru.
Findings First, the maximum throughput of the divisional seru is better than that of the rotating seru under
suitable worker assignment. Second, in the seru which has less difference of task time, throughput performance
of the rotating seru is better than the divisional seru when the NT is close to the number of assigned workers.
Moreover, the influence tendency of the four factors on throughput gap between the two seru types is significant.
Originality/value This research addresses the worker-task assignment for divisional and rotating seru
based on their characteristics. Several findings can help decision maker select more applicable seru type
according to various production environments from the perspective of optimum throughput.
Keywords Throughput, Divisional seru, Rotating seru, Seru manufacturing system, Worker assignment
Paper type Research paper
Nomenclature
Indices
jindex of tasks (j¼1, 2, ,J)
kindex of workers (k¼1, 2, ,K)
Input parameters
Jthe number of tasks
Kthe number of workers
T
j
processing time of task j
w
kj
skill level weight of worker kat task j
BW upper boundary of required workers
Havailable time in planning period
Industrial Management & Data
Systems
Vol. 118 No. 5, 2018
pp. 1114-1136
© Emerald PublishingLimited
0263-5577
DOI 10.1108/IMDS-07-2017-0303
Received 12 July 2017
Revised 17 December 2017
Accepted 28 January 2018
The current issue and full text archive of this journal is available on Emerald Insight at:
www.emeraldinsight.com/0263-5577.htm
This work was supported by the China Postdoctoral Science Foundation (Grant No. 2016M602528).
The authors are grateful for the financial supports.
1114
IMDS
118,5
Decision variables
x
kj
1, if worker kis assigned to task
j; 0, otherwise
N
k
1, if worker kis assigned to seru;
0, otherwise
WL
k
workload of worker k
A
j
total time that all assigned workers
spend on task jin rotating seru
B
k
total time that worker kspends
to complete all tasks in rotating seru
TP throughput of seru
MWL workload of bottleneck worker
1. Introduction
Market environments are becoming more close to diverse customer need, short product life
cycles, multi-product and small-lot-size production.These changes are forcing manufacturers
to improve the efficiency and flexibility of their production. However, traditional production
methods cannot accommodate rapidly changing market very well. Forward-looking
manufacturers must prepare themselves to be able to quickly adjust or respond to the
market changes. It is pressing to develop the advanced manufacturing techniques and
philosophiesneeded by multi-product and small-lot-size productionsystems characterized by
a variety of processes, fluctuation of productive capacity and scheduling, uncertain external
conditions and dynamic demand (Joseph and Sridharan, 2011; Brecher, 2015).
Seru manufacturing system is an innovative production mode developed by Japanese
electronics manufacturing companies (Stecke et al., 2012). Starting from the 1990s, many
Japanese electronics manufacturing companies such as Canon, Sony, Panasonic, Fujitsu,
NEC and Hitachi have transformed their conveyor assembly lines into a work-cell-based
manufacturing system (Yin et al., 2008a, b; Liu et al., 2010; Stecke et al., 2012). A work-cell is
called seru in Japanese. Most of the companies using seru have achieved huge profits,
especially Canon. Since 1998, Canon reconfigured 20,000m conveyor assembly lines by
introducing seru system into its 54 plants across the world. As a result, 720,000 square
meters of shop-floor space was saved, work-in-process inventory turnover was reduced
from three days to six hours, and total cost was decreased from 62 to 50 percent (Yin et al.,
2008). Since then, the seru manufacturing system had attracted wide attention from
factories worldwide and the academic world (Takahashi et al., 2006).
The seru manufacturing system has generally been acknowledged as a human-centered
production (Kaku et al., 2008; Liu et al., 2010; Stecke et al., 2012). One or several multi-skilled
workers carry out all tasks individually or cooperatively in each seru. There are three
basic types of serus: divisional seru, rotating seru and yatai (see Figure 1) (Sakazume, 2005;
Yin et al., 2008a).
Yatai
Station-1
Station-3
Station-2
Rotating Seru
Station-1
Station-3
Station-2
Divisional Seru
Station-1
Station-3
Station-2
(a) (b) (c)
Notes: (a) Divisional seru; (b) rotating seru; (c) yatai
Figure 1.
Diagram of seru types
1115
Cross-trained
worker
assignment

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