suppose that we do arrive at a good solution solely on the basis of material handling cost, such as the shown in exhibit 8.7 (whose total cost is $3,550). We would note, first of all that our shipping and receiving workcenter is near the center of the cfactory-and arrangement that probably would not be acceptable. The sewing workcenter is next to the painting workcenter, introducing the hazard that lint, thread, and cloth particles might drift onto painted items. Futher, small toy assembly and large toy assembly are located at opposite ends of the plant, which would increase travel time foe assemblers (who very likely would be needed in both workcenter at various times of the day) and for supervisors (who might otherwise supervise both workcenter simultaneously). Often factor other than material handling cost need to be considered in finalizing a layout.
systematic layout planning
In certain types of layout problems, numerical flow of items between workcenters either is impractical to obtain or dose not reveal the qualitative factors that may be crucial to the placement decision. In these situations, the venerable technique known as systematic layout planning(SLP) can be used. It involves developing a relationship chart showing the degreeof importance of having each workcenter located adjacent to every other workcenter. Form this chart, an activity relationship diagram, similar to the flow graph used for illustrating material handling between workcenter, is developed. The activity relationship diagram is then adjusted by trial and error until a satisfactory adjacency pattern is obtained. This pattern inturn, is modified workcenter by workcenter to meet building space limitations. Exhibit 8.8 illustrates the technique with a simple five-workcenter problem involving layingout a floor of a deparment store.
Assembly Lines
The term assembly line refers to progressive assembly linked by some material handling device. The usual assumption is that some form of pacing is present and the allowable processing time is equivalent for all workstations. Within this broad definition, there are important differences among line types. A few of these are material handling device (belt of roller conveyer, overhand crane); line configuration (U-shape, straight, branching); pacing (mechanical, human); product mix (one product or multiple products); workstation characteristics (workers may sit, stand, walk with the line, or ride the line); and length of the line (few or many worker).