The definition of assembly line balancing difficulty and evaluation of balance solution quality

Assembly line balancing is a classic ill-structured problem where total enumeration is infeasible and optimal solutions uncertain for industrial problems. A quantitative approach to classifying problem difficulty and solution quality is therefore important. Two existing measures of difficulty, order strength and west ratio are compared to a new compound expression of difficulty, project index. Project index is based on individual assessment of precedence (precedence index) and task time (task time index). The current working definition of project index is given. Early criteria for judging assembly lines use balance delay and smoothness index, both are flawed as criteria. Line and balance efficiency are developed as more appropriate. Project index, line and balance efficiency will be illustrated for a published test-case examined by the "A similar to Line" balancing package. The potential for a "learning" approach, selecting models to suit problems using the measures of difficulty, will form part of the conclusions within this paper. (C) 2001 Elsevier Science Ltd. All rights reserved.