Integrated line balancing to attain Shojinka in a multiple straight line facility

This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Traditional straight assembly lines are still one of the most important elements and an important fact of today's production systems. If applicable, a company can combine its multiple straight assembly lines and obtain many advantages of Shojinka more or less. This paper analyses a new problem – integrated balancing of multiple straight assembly lines (MSLB) to attain Shojinka in a multiple straight assembly line facility. The MSLB problem is built on the concept that it could be possible for a company to obtain the advantages of Shojinka even if the company has not adopted the U-shaped line layout. Three connectivity types are suggested to integrate multiple assembly lines. A binary integer formulation for integrated balancing of multiple assembly lines is developed. The objective of the proposed formulation is to minimise the total number of workstations required in the assembly facility. The formulation is explained and validated using some illustrative examples. The proposed approach provides flexibility to minimise the total idle times of the lines and total number of workstations that are required in the assembly line facility. 1. Introduction 'Shojinka' is a Japanese word that is a combination of sho (to reduce), jin (worker) and ka (to change) (Sennott et al. 2006). The concept of Shojinka, which was originally an important element of Toyota Production System (TPS), is easily to increase or decrease the number of workers in a production facility when the demand rate is increased or decreased. In a production facility, different types of products may be produced on different lines. The fluctuations in demands of products will probably require adding workers to some lines and removing from others. Attaining flexibility in the number of workers at a workshop to adapt to demand …