Problem formulation
In this section the mathematical model of cell formation problem is presented based on dynamic cellular manufacturing
system with worker assignment. The objective is minimizing the sum of the penalty of deviation of production volume from
the desirable value of the part demand (holding and backorder cost), inter-cell material handling, machine and reconfigura-
tion, hiring, firing and salary worker costs. Main constraints are machine capacity, available time of workers, and production
volume. The problem is formulated according to the following assumptions:
The processing time of each operation of each part type on each machine type is known.
The demand for each part type in each period is known.
The capacity of each machine type is known.
The available time of each worker type is known.
The number of cells is given and constant through all periods.
Only one worker is allotted for processing each part on each corresponding machine type.
Inter-cell material handling cost is constant for all moves regardless of distances.
Holding and backorder inventories are allowed between periods with known costs. Thus, the demand for a part in a given
period can be satisfied in the preceding or succeeding periods.
Maintenance and overhead costs of each machine type are known. These costs are considered for each machine in each
cell and period irrespective of whether the machine is active or idle.
System reconfiguration involves the addition and removal of machine to any cell and relocation from one cell to another
between periods.
Salary of each worker type is known. This cost is considered for each worker in each cell and period irrespective of
whether the worker is active or idle.
Reconfiguration involves the addition and removal of worker (hiring and firing) to any cell and relocation from one cell
to another between periods.
ีutilization