Learning Objectives Define layout planning and its importance Identify and describe different types of layouts Compare process layouts & product layouts Describe the steps involved in designing both process and product layouts Explain the advantages of hybrid layouts Define the meaning of group technology & its importance to cellular layouts
What Is Layout Planning Layout planning is determining the best physical arrangement of resources within a facility Two broad categories of operations: Intermittent processing systems Continuous processing systems
Types of Layouts Process layouts: Group similar resources together Product layouts: Designed to produce a specific product efficiently Hybrid layouts: Combine aspects of both process and product layouts Fixed-Position layouts: Product is two large to move; e.g. a building
Process Layouts General purpose & flexible resources Lower capital intensity & automation Higher labor intensity Resources have greater flexibility Processing rates are slower Material handling costs are higher Scheduling resources & work flow is more complex Space requirements are higher
Product Layouts Specialized equipment High capital intensity & wide use of automation Processing rates are faster Material handling costs are lower Less space required for inventories Less volume or design flexibility
Hybrid Layouts Combine elements of both product & process layouts Maintain some of the efficiencies of product layouts Maintain some of the flexibility of process layouts Examples: Group technology & manufacturing cells Grocery stores
Comparison of Product vs. Product Layouts Process Layouts Product LayoutsProducts: large #, different small # efficientlyResources: general purpose specializedFacilities: more labor intensive more capital intensiveFlexibility: greater relative to market lower relative to marketProcessing slower fasterRates:Handling costs: high lowSpace requirements: higher lower
Designing Process Layouts Step 1: Gather information: Space needed, space available, importance of proximity between various units Step 2: Develop alternative block plans: Using trial-and-error or decision support tools Step 3: Develop a detailed layout Consider exact sizes and shapes of departments and work centers including aisles and stairways Tools like drawings, 3-D models, and CAD software are available to facilitate this process
Process Layout Steps Step 1: Gather information like space needed, from-to matrix, and REL Chart for Recovery First Sports Medicine Clinic (total space 3750 sq. ft.) A B C Radiology Laboratory Lobby & Waiting 400 sq. ft. 300 sq. ft. 300 sq. ft. D E F Examining Surgery & Physical Rooms Recovery Therapy 800 sq. ft. 900 sq. ft. 1050 sq. ft.
Step 2: Develop a New Block Layout Use trial and error with from-to and REL Charts as a guide Use computer software like ALDEP or CRAFT
Warehouse Layouts Warehouse Layout Considerations: Primary decision is where to locate each department relative to the dock Departments can be organized to minimize “ld” totals Departments of unequal size require modification of the typical ld calculations to include a calculation of the “ratio of trips to area needed” The usage of “Crossdocking” (see Ch.4) modifies the traditional warehouse layouts; more docks, less storage space, and less order picking
Office Layouts Office Layout Considerations: Almost half of US workforce works in an office environment Human interaction and communication are the primary factors in designing office layouts Layouts need to account for physical environment and psychological needs of the organization One key layout trade-off is between proximity and privacy Open concept offices promote understanding & trust Flexible layouts incorporating “office landscaping” help to solve the privacy issue in open office environments
Designing Product Layouts Step 1: Identify tasks & immediate predecessors Step 2: Determine the desired output rate Step 3: Calculate the cycle time Step 4: Compute the theoretical minimum number of workstations Step 5: Assign tasks to workstations (balance the line) Step 6: Compute efficiency, idle time & balance delay
Step 1: Identify Tasks &Immediate PredecessorsExample 10.4 Vickis Pizzeria and the Precedence Diagram Immediate Task TimeWork Element Task Description Predecessor (seconds A Roll dough None 50 B Place on cardboard backing A 5 C Sprinkle cheese B 25 D Spread Sauce C 15 E Add pepperoni D 12 F Add sausage D 10 G Add mushrooms D 15 H Shrinkwrap pizza E,F,G 18 I Pack in box H 15 Total task time 165
Layout Calculations Step 2: Determine output rate Vicki needs to produce 60 pizzas per hour Step 3: Determine cycle time The amount of time each workstation is allowed to complete its tasks available time ( sec./day ) 60 min/hr x 60 sec/min Cycle time (sec./unit) = = = 60 sec./unit desired output ( units/hr ) 60 units/hr Limited by the bottleneck task (the longest task in a process): available time 3600 sec./hr.Maximum output = = = 72 units/hr, or pizzas per hour bottleneck task time 50 sec./unit
Layout Calculations (continued) Step 4: Compute the theoretical minimum number of stations TM = number of stations needed to achieve 100% efficiency (every second is used) TM = ∑ ( task times ) = 165 seconds = 2.75, or 3 stations cycle time 60 sec/station Always round up (no partial workstations) Serves as a lower bound for our analysis
Layout Calculations (continued) Step 5: Assign tasks to workstations Start at the first station & choose the longest eligible task following precedence relationships Continue adding the longest eligible task that fits without going over the desired cycle time When no additional tasks can be added within the desired cycle time, begin assigning tasks to the next workstation until finished Workstation Eligible task Task Selected Task time Idle time A A 50 10 1 B B 5 5 C C 25 35 2 D D 15 20 E, F, G G 15 5 E, F E 12 48 F F 10 38 3 H H 18 20 I I 15 5
Last Layout Calculation Step 6: Compute efficiency and balance delay Efficiency (%) is the ratio of total productive time divided by total time Efficiency (%) = ∑t = 165 sec. ( 100) = 91.7% NC 3 stations x 60 sec. Balance delay (%) is the amount by which the line falls short of 100% Balance delay = 100% − 91.7% = 8.3%
Other Product Layout Considerations Shape of the line (S, U, O, L): Share resources, enhance communication & visibility, impact location of loading & unloading Paced versus un-paced lines Paced lines use an automatically enforced cycle time Single or mixed-model lines
Designing Hybrid Layouts One of the most popular hybrid layouts uses Group Technology (GT) and a cellular layout GT has the advantage of bringing the efficiencies of a product layout to a process layout environment
Chapter 10 Highlights Layout planning is deciding on the best physical arrangement of resources. There are four basic types of layouts: process, product, hybrid, and fixed position. Process layouts provide flexibility to make a variety of different products. Product layouts provide greater efficiency for one product. The steps for designing process layouts are: gather space and closeness information, develop a block plan, and develop a detailed layout.
Chapter 10 Highlights (continued) The steps for designing an product layout are: identify tasks and predecessors, determine output rate, determine cycle time, computing the theoretical minimum number of work stations, assigning tasks to workstations, and computing efficiency and balance delay. Hybrids layouts combine elements from both types of layouts to increase efficiency. Hybrid layouts combine GT analysis with cellular layout concepts .