om ch 2.5 Layouting.pptx
- 2. Introduction Layout refers to the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system. The basic objective of layout design is to facilitate a smooth flow of work, material, and information through the system Other Supporting objectives includes To facilitate attainment of product or service quality To use workers and space efficiently To avoid bottlenecks To minimize material handling costs To eliminate unnecessary movements of workers or materials To minimize production time or customer service time To design for safety 2
- 3. Inefficient operations High Cost Bottlenecks Changes in the design of products or services The introduction of new products or services Accidents or Safety hazards Changes in volume of output or mix of products Changes in methods and equipment Changes in environmental or other legal requirements 3 The Need for Layout Decisions
- 4. Inputs to the Layout Decision 1.Specification of objectives of the system in terms of output and flexibility 2.Estimation of product or service demand on the system 3.Processing requirements in terms of number of operations and amount of flow between departments and work centers 4. Space requirements for the elements in the layout 5. Space availability within the facility itself 4
- 5. Layout Types There are 3 basic types and one hybrid type Basic types Product layouts-(production lines or assembly lines Process layouts- it is also called functional/job shop/batch process/ Fixed-Position layout-All facilities are brought and arranged around one work center Hybrid type Group Technology or Cellular layouts 5
- 6. Basic Layout Types Product layout Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow Equipment or work processes are arranged according to the progressive steps by which the product is made Product layouts are most conducive to repetitive or Continuous Processing 6
- 7. Product layouts 7 A U-Shaped Production Line
- 8. Advantages of Product Layout High rate of output Low unit cost due to high volume Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling(in the initial design of the system) Routing accounting, purchasing and inventory control Little direct supervision is required 8
- 9. Disadvantages of Product Layout Creates dull, repetitive jobs Poorly skilled workers may not maintain equipment or quality of output Fairly inflexible to changes in volume Highly susceptible to shutdowns A breakdown of one machine in a product line may cause stoppages of machines in the downstream of the line Needs preventive maintenance Incentive plans tied to individual output are impractical l 9
- 10. Process layout/ similar resources or processes are located together. Layout that can handle varied processing requirement The layouts include departments or other functional groupings in which similar kinds of activities are performed Designed to facilitate processing items or providing services that present a variety of processing requirements E.g – hospital some services such as -X-ray and laboratories - machine shop, which has separate departments for milling, grinding, drilling, and so on 10
- 12. Advantages of Process Layout Can handle a variety of processing requirements Not particularly vulnerable to equipment failures General-purpose equipment is less costly and is easier and less costly to maintain Possible to use individual incentive systems 12
- 13. Disadvantages of Process Layout In-process inventory is relatively high and its costs can be high Routing and scheduling pose continual challenges Equipment utilization rates are low Material handling is slow and inefficient, and more costly per unit Job complexities reduce the span of supervision and result higher supervisory costs Special attention necessary for each product or customer and low volumes result in higher unit costs Accounting, inventory control, and purchasing are much more involved 13
- 14. Product and Process layouts 14
- 15. Product and Process layouts 15
- 16. Fixed Position Layouts Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed. Nature of the product dictates this type of layout Weight Size Bulk Widely used for farming, firefighting, road building, home building, power plants, dams construction, shipbuilding, and oil drilling In each case, compelling reasons bring workers, materials, and equipment to the “product’s” location instead of the other way around. 16
- 18. Advantages of fixed layout Reduces movement of machines & equipment Minimizes damage/cost of movement Continuity of assigned work force 18
- 19. Disadvantages of fixed layout Skilled & versatile workers needed due to multiple operations Skill combination may be difficult to obtain higher pay Movement of people/material may be expensive Equipment utilization low as they are left at location for subsequent usage instead of being moved as & where needed 19
- 20. Hybrid Layout Many operations either design themselves hybrid layouts which combine elements of some or all of the basic layout types or use the ‘pure’ basic layout types in different parts of the operation 20
- 21. Designing Product Layouts: Line Balancing - Harmonizing the Content of Work The goal of a product layout is to arrange workers or machines in the sequence that operations need to be performed. The sequence is referred to as a production line or an assembly line. These lines range from fairly short, with just a few operations, to long lines that have a large number of operations A key issue in product layouts is that the tasks in the assembly line or flow line must be 'balanced'. This means that the time spent by components or customers should be approximately the same for each workstation, otherwise queues will occur at the slowest workstation 21
- 22. Line balancing Line Balancing is the process of assigning tasks to workstations in a manner that minimizes the number of workstations and the total amount of idle time at all stations for a given output level Objective Balance the assembly line i.e. minimize the imbalance between machines or personnel while meeting required output 22
- 23. Line Balancing Procedure 1. Specify the sequential relationship among tasks using a precedence diagram 2. Calculate the cycle time required for line 3. Calculate the theoretical minimum number of workstations required produce a specified rate of output 4. Assigned tasks to workstations (one task at a time) recognizing cycle time and precedence constraints a. All preceding tasks in the sequence have been assigned. b. The task time does not exceed the time remaining at the workstation If no tasks are eligible, move on to the next workstation Break ties that occur between tasks using one of these rules as a primary rule and the other as secondary criteria a. Assign the task with the longest task time b. Assign the task with the greatest number of followers If there is still a tie, choose one task arbitrarily. 5. Calculate efficiency of line 6. Determine if theoretical minimum number of workstations or an acceptable efficiency level has been reached. If not, go back to step 5, and rebalance by interchanging primary and secondary rules 23
- 24. Example 24 Suppose that the work required to fabricate 500 products per day can be divided up into 11 tasks, with the task time and precedence relationship as shown in the table. Production per day is 420 minutes.
Editor's Notes
- #22: Harmonizing the content of work means to design the following so that they require the same length of time: (1) the various production structure levels, and (2) the times required for individual operations within a production structure level.