Intra-cell manpower transfers and cell loading in labor-intensive manufacturing cells Gu ¨rsel A. Su ¨er a, * , Cihan Dagli b a Industrial and Manufacturing Systems Engineering, Stocker Center 274, Ohio University, Athens, OH 45701, USA b Engineering Management, 229 Engineering Management Building, 1870 Miner Circle, Rolla, MO 65409-0370, USA Received 1 April 2001; revised 1 December 2002; accepted 1 March 2003 Available online 18 January 2005 Abstract Labor-intensive manufacturing cells consist of simple machines and equipment that require continuous operator attendance and involvement. Operators are often re-assigned to different machines when a new product is released to the cell. The main reason for this re-assignment is to maximize the output rate of the cell by balancing the flow of products through several machines with varying capacities. In this paper, first a product-sequencing problem with the objective of minimizing the total intra-cell manpower transfers is introduced. A three-phase hierarchical methodology is proposed to solve the problem optimally. Next, manpower transfer matrix values are modified considering the distances traveled among machines. In the second part of the paper, a machine-level-based similarity coefficient that uses the number of machines as a similarity measure is discussed. Later, these coefficients are used during the cell loading process to minimize makespan and also machine and space requirements. Manpower allocation decisions are made along with scheduling decisions that are critical in most labor-intensive manufacturing cells and both approaches are illustrated with an example problem. q 2005 Elsevier Ltd. All rights reserved. Keywords: Cell loading; Manpower transfers; Labor-intensive manufacturing cells 1. Introduction This paper focuses on labor-intensive cells where most of the operations require light weight, and small machines and equipment that require continuous operator attendance and involvement. Therefore, the assignment of operators to machines directly affects the output of the cell. The number of operators is 0360-8352/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.cie.2003.03.006 Computers & Industrial Engineering 48 (2005) 643–655 www.elsevier.com/locate/dsw * Corresponding author. Tel.: C1 740 593 1542; fax: C1 740 593 0778. E-mail addresses: suer@bobcat.ent.ohiou.edu (G.A. Su ¨er), dagli@umr.edu (C. Dagli).