Chapter 10 Facility Layout Operations Management by R

Chapter 10 – Facility Layout Operations Management by R. Dan Reid & Nada R. Sanders 3 rd Edition © Wiley 2007

Learning Objectives n n n 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 n n n Layout planning is determining the best physical arrangement of resources within a facility Facility resource arrangement can significantly affect productivity. Two broad categories of operations: n n Intermittent processing systems—low volume of many different products Continuous processing systems—high volume of a few standardized products

Facility Layout n Fixed Position Product is too large to move; e. g. : a building n n Process n n Product n n Group similar resources together Designed to produce a specific product efficiently Hybrid: combines aspects of both process and product layouts n n Cellular Modular

Fixed Position Layout n n n The position of a product or customer is fixed; and materials, equipment, workers, and other resources are transported to and from the product or customer. Usually used because product movement is difficult (ship building) or for convenience (on-site repair). This is often managed through Project Management (Chapter 16).

Process Layout n n n Similar processes/functions are grouped together (job shop). Volume of parts/services does not warrant product or cellular layout. Primary advantages--flexibility, utilization of machinery/equipment. Disadvantages--greater handling of materials/customers, more complex scheduling, WIP/waiting lines, departmental boundaries

Traditional Process Layout

Process Layouts n n n n 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

Designing Process Layouts n Step 1: Gather information: n n Step 2: Develop alternative block plans: n n Space needed, space available, importance of proximity between various units Using trial-and-error or decision support tools Step 3: Develop a detailed layout n n Consider exact sizes and shapes of departments and work centers including aisles and stairways Tools like drawings, 3 -D models, and CAD software available to facilitate this process

Comparing Alternatives n Load-distance measures n n n REL charts: n n Load: # of trips, weight moved, $-value moved Distance: rectilinear distance (using north-south & east-west movements) Management opinion on strength of relationships Software tools: n n CRAFT: computerized relative allocation of facilities technique ALDEP: automated layout design program

Process Layout Example

Process Layout Steps n 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 Radiology B Laboratory 400 sq. ft. 300 sq. ft. C Lobby & Waiting 300 sq. ft. D Examining Rooms 800 sq. ft. E Surgery & Recovery 900 sq. ft. F Physical Therapy 1050 sq. ft.

Step 1: Gather Information (continued)

Step 2: Develop a Block Layout n n Use trial and error with from-to and REL Charts as a guide Use computer software like ALDEP or CRAFT

Warehouse Layouts n Warehouse Layout Considerations: n n 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 n Office Layout Considerations: n n n 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

Product Layout n Processes/work stations arranged in sequence of activities required to produce the product/service (Assembly Line). n n n Use for high volume, standardized products and services WIP and handling of materials/customers is minimized Equipment is specialized, capital intensive Output is dependent on the slowest work station The “line” must be balanced for effectiveness.

Product Layouts n n n 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

Product Layout Product A Product B Product C 7 -14 Step 1 Step 2 Step 3 Step 1 Step 3 Step 4

Designing Product Layouts n n n Step 1: Identify tasks & immediate predecessors Step 2: Determine the desired output rate Step 3: Calculate the cycle time Step 4: Compute theoretical minimum number of workstations Step 5: Assign tasks to workstations (balance the line) Step 6: Compute efficiency, idle time & balance delay

Assembly Line Balancing 1. 2. 3. 4. Precedence diagram: circles=tasks, arrows show the required sequence. Determine cycle time: Determine required workstations (theoretical minimum) Set rules for assigning tasks (number of following tasks, longest task time)

Assembly Line Balancing 6. Assign tasks to first workstation, using rules and staying within cycle time. Repeat for following workstations until all tasks are assigned. Evaluate line efficiency: 7. Rebalance if efficiency is not satisfactory. 5.

Step 1: Identify Tasks & Immediate Predecessors

Layout Calculations n Step 2: Determine output rate n n Vicki needs to produce 60 pizzas per hour Step 3: Determine cycle time n The amount of time each workstation is allowed to complete its tasks n Limited by the bottleneck task (the longest task in a process):

Layout Calculations n (continued) Step 4: Compute theoretical minimum number of stations n n n TM = number of stations needed to achieve 100% efficiency (every second is used) Always round up (no partial workstations) Serves as a lower bound for our analysis

Layout Calculations n (continued) Step 5: Assign tasks to workstations n n n 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

Last Layout Calculation n Step 6: Compute efficiency and balance delay n n Efficiency (%) is the ratio of total productive time divided by total time Balance delay (%) is the amount by which the line falls short of 100%

Other Product Layout Considerations n Shape of the line (S, U, O, L): n n Paced versus un-paced lines n n Share resources, enhance communication & visibility, impact location of loading & unloading Paced lines use an automatically enforced cycle time Number of products produced n n Single Mixed-model lines

Comparison of Product vs. Product Layouts Products: Process Layouts large #, different Product Layouts small # efficiently Resources: general purpose specialized Facilities: more labor intensive more capital intensive Flexibility: greater relative to market lower relative to market Processing Rates: slower faster Handling costs: high low Space requirements: higher lower

Hybrid Layouts n Combine elements of both product & process layouts n n n Maintain some of the efficiencies of product layouts Maintain some of the flexibility of process layouts Examples: n n Group technology & manufacturing cells Grocery stores

Hybrid Layouts n Cellular Layout n n Cross between product/process layout group a number of machines into a cell to produce a family of parts requiring similar processing (group technology). Often arranged into U- or C-shaped line flows Modular Layout n achieves layout flexibility so that layouts can be changed, expanded, or reduced without much difficulty.

Designing Hybrid Layouts n n 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

Process Flows before the Use of GT Cells

Process Flows after the Use of GT Cells

Facility Layout Across the Organization n Layout planning is organizationally important for an efficient operations n n n Marketing is affected by layout especially when clients come to the site Human resources is affected as layout impacts people Finance is involved as layout changes can be costly endeavors

Chapter 10 Highlights n n 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 n n n (continued) The steps for designing an product layout are: identify tasks and predecessors, determine output rate, determine cycle time, computing 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.

Chapter 10 Homework Hints n n 10. 8: Assign sites based on number of trips (refer to Example 10. 2). There is no strategy regarding which side of the aisle to assign—just nearness to the dock. 10. 16: Follow the steps. This is a product layout (assembly line balancing). The book has an example on pages 360 -366, which is also on the slides covered in class.

Sample Problem— 10. 7 Department Category Trips to/from dock 1 Sports t-shirts 50 2 Men’s t-shirts 63 3 Women’s t-shirts 35 4 Children’s t-shirts 55 5 Fashion t-shirts 48 6 Undershirts 60

Sample Problem – 10. 15 Task Imm. predecessor Task time (sec) A None 55 B A 30 C A 22 D B 35 E B, C 50 F C 15 G F 5 H G 10 TOTAL 222 n n n n Draw precedence diagram Determine cycle time—demand = 50 units/hr Theoretical minimum no. of work stations Assign tasks to workstations using cycle time Efficiency and balance delay of line? Bottleneck? Maximum output?