Virtual cellular manufacturing cell formation multi-objective problem by weighted sum goal programming method

Abstract

There are some reasons why a functional layout is still dominant in manufacturing industry and why some firms have even shifted from a cellular layout back to functional layout. Reorganizing in cellular layout to meet the changes required is time consuming and costly. If the change occur frequently, reconfiguration may become impractical or not a feasible. A relatively new alternative has been considered in recent years, known as virtual cellular manufacturing systems (VCMS). The few explanations for this arrangement are as follows. Firstly, the cellular layout reorganizes to cells to accommodate the necessary adjustments is expensive and time consuming. Secondly, reconfiguring could become unfeasible or impractical, costly if the changes happen often. VCMS are a relatively a new alternative that has been into consideration. A temporary grouping of equipment, jobs and personnel to achieve the advantages typical considered. A logical collection of workstations that are not necessarily arranged in close proximity to one another is called a virtual cell. For effective implementation, workers issue is important in VCMS. Therefore, in this paper, jobs, machinery and workers are logically grouped according to predetermined logic. It only exists in the imaginations of the employees and in the production control system. Though machines are not physically moved into cells, their functional arrangement is maintained. Depending on shifts, and as per the production quantities and product mix, virtual manufacturing cells are generated on a weekly, fortnightly or monthly basis. This paper also discusses a few of the key features of VCMS i.e. virtual cellular manufacturing system. A multiple objectives mathematical problem is formed for VCMS is discussed. Maximize total productive hours and minimize the set up time thereby reduce intercellular dependencies are the objectives considered. The weighted sum goal programming method is used to obtain the solutions of the mathematical formulation. Factors such as capacity constraints, cell size restrictions, load imbalance minimization, minimization of intercellular movements and labor flexibility are considered. Solving in Lingo v20 platform, results are obtained of the two hypothetical problems for getting cells. As the number of cells increases, more number of jobs is accommodated and demand for more number of machines increases. Job priority is incorporated in the second problem. It facilitates the formation of cells with change in parameters. Different cell formations are obtained with job priority. Therefore, implementation of VCMS is an important issue.