operation management
Post on 18-Nov-2014
583 Views
Preview:
DESCRIPTION
TRANSCRIPT
Technical Note 5
Facility Layout
Innovations at McDonald’s
Indoor seating (1950s)Indoor seating (1950s) Drive-through windowDrive-through window (1970s) (1970s) Adding breakfast to the menu Adding breakfast to the menu
(1980s)(1980s) Adding play areas (1990s)Adding play areas (1990s)
Three out of the four are Three out of the four are layout decisions!layout decisions!
Facility Layout
Facility layout can be defined as the process by which the placement of departments, workgroups within departments, workstations, machines, and stock-holding points within a facility are determined.
Characteristics of a Good Layout
Layout Design Considerations
Higher Higher utilization of spaceutilization of space, equipment, , equipment, and peopleand people
Improved Improved flow of informationflow of information, materials, , materials, or peopleor people
Improved Improved employee moraleemployee morale and safer and safer working conditionsworking conditions
Improved Improved customer/client interactioncustomer/client interaction
FlexibilityFlexibility
Basic Layout Formats
Process Layout
Product Layout
Group Technology (Cellular) Layout
Fixed-Position Layout
Process-Oriented Layout
Design places departments with large flows of material or people together
Dept. areas have similar processes, eg all lathes in one area & all stamping machines in another
Used with process-focused processes
© 1995 Corel Corp.
Layout Types
FoundryMilling
machines
LathesGrinding
Painting Drills
Office
Welding
Forging
(a) Process Layout(a) Process Layout
Can handle a variety of processing requirements
Not particularly vulnerable to equipment failures
Equipment used is less costly Possible to use individual incentive
plans
Advantages of Process Layouts
In-process inventory costs can be high Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Complexities often reduce span of
supervision
Disadvantages of Process Layouts
Product-Oriented Layout
Equipment is arranged according to the steps by which the product is made.
Used when batch size is large Types: Fabrication line; assembly line Examples
© 1984-1994 T/Maker Co.
Layout Types
(b) Layout of a production line(b) Layout of a production line
Station 1 Station 2 Station 3 Station 4
1 2 3 4
5
6
78910
In
Out
Workers
Figure 6.6A U-Shaped Production Line
High rate of output Low unit cost Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling Fairly routine accounting and
purchasing
Advantages 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 Needs preventive maintenance Individual incentive plans are
impractical
Disadvantages of Product Layout
Cellular Layout - Group Technology (Work Cells)
Groups dissimilar machines into work centers (or cells) to work on similar products.
Group Technology
Machine 1
Machine 2
Machine 3
Machine 4Machine
5
Materials in
Finished goods out
One Worker, Multiple MachinesOne Worker, Multiple Machines
Group TechnologyDrilling
D D
D D
Grinding
G G
G G
G G
Milling
M M
M M
M M
Assembly
A A
A A
Lathing
Receiving and shipping
L
L L
L L
L L
L
(a) Jumbled flows in a job shop without GT cells(a) Jumbled flows in a job shop without GT cells
Group Technology
(b) Line flows in a job shop with three GT cells (b) Line flows in a job shop with three GT cells
Cell 3
L M G G
Cell 1 Cell 2
Assembly area
A A
L M DL
L MShipping
D
Receiving
G
Fixed-Position Layout
Design is for stationary project Workers & equipment come to site Complicating factors
– Limited space at site
Examples
© 1995 Corel Corp.
© 1995 Corel Corp.
© 1995 Corel Corp.
Fixed Position Layout
Question: What are our primary considerations for a fixed position layout?
Answer: Arranging materials and equipment concentrically around the production point in their order of use.
Process Layout: Interdepartmental Flow Given
– The flow (number of moves) to and from all departments
– The cost of moving from one department to another
– The existing or planned physical layout of the plant
Determine– The “best” locations for each department, where
best means interdepartmental transportation, or flow, costs
Process Layout Example
1.1. Construct a “from-to matrix”Construct a “from-to matrix”
2.2. Determine the space requirementsDetermine the space requirements
3.3. Develop an initial schematic diagramDevelop an initial schematic diagram
4.4. Determine the cost of this layout Determine the cost of this layout
5.5. Try to improve the layoutTry to improve the layout
6.6. Prepare a detailed plan Prepare a detailed plan
Arrange six departments in a factory to Arrange six departments in a factory to minimize the material handling costs. minimize the material handling costs. Each department is 20 x 20 feet and the Each department is 20 x 20 feet and the building is 60 feet long and 40 feet wide.building is 60 feet long and 40 feet wide.
DepartmentDepartment AssemblyAssembly PaintingPainting MachineMachine ReceivingReceiving ShippingShipping TestingTesting(1)(1) (2)(2) Shop (3)Shop (3) (4)(4) (5)(5) (6)(6)
Assembly (1)Assembly (1)
Painting (2)Painting (2)
Machine Shop (3)Machine Shop (3)
Receiving (4)Receiving (4)
Shipping (5)Shipping (5)
Testing (6)Testing (6)
Number of loads per weekNumber of loads per week
50 100 0 0 20
30 50 10 0
20 0 100
50 0
0
Process Layout Example
Figure 9.4Figure 9.4
Room 1Room 1 Room 2Room 2 Room 3Room 3
Room 4Room 4 Room 5Room 5 Room 6Room 660’60’
40’40’
Process Layout Example
Receiving Shipping TestingDepartment Department Department
(4) (5) (6)
Figure 9.5Figure 9.5
Assembly Painting Machine ShopDepartment Department Department
(1) (2) (3)
100100
5050
2020
5050
5050
20201010
100100
3030
Process Layout Example
Interdepartmental Flow GraphInterdepartmental Flow Graph
1 2 3
4 5 6
Figure 9.6Figure 9.6
Process Layout Example
Cost Cost == $50$50 ++ $200$200 ++ $40$40(1 and 2)(1 and 2) (1 and 3)(1 and 3) (1 and 6)(1 and 6)
++ $30$30 ++ $50$50 ++ $10$10(2 and 3)(2 and 3) (2 and 4)(2 and 4) (2 and 5)(2 and 5)
++ $40$40 ++ $100$100 ++ $50$50(3 and 4)(3 and 4) (3 and 6)(3 and 6) (4 and 5)(4 and 5)
= $570= $570
Cost = Cost = ∑ ∑∑ ∑ X Xijij C Cijij
nn
i i = 1= 1
nn
j j = 1= 1
Room 1Room 1 Room 2Room 2 Room 3Room 3
Room 4Room 4 Room 5Room 5 Room 6Room 660’60’
40’40’
Process Layout Example
Receiving Shipping TestingDepartment Department Department
(4) (5) (6)
Figure 9.8Figure 9.8
Painting Assembly Machine ShopDepartment Department Department
(2) (1) (3)
Process Layout Example
3030
5050
1010
5050
50502020
5050 100100
100100
Interdepartmental Flow GraphInterdepartmental Flow Graph
2 1 3
4 5 6
Figure 9.7Figure 9.7
Process Layout Example
Cost Cost == $50$50 ++ $100$100 ++ $20$20(1 and 2)(1 and 2) (1 and 3)(1 and 3) (1 and 6)(1 and 6)
++ $60$60 ++ $50$50 ++ $10$10(2 and 3)(2 and 3) (2 and 4)(2 and 4) (2 and 5)(2 and 5)
++ $40$40 ++ $100$100 ++ $50$50(3 and 4)(3 and 4) (3 and 6)(3 and 6) (4 and 5)(4 and 5)
= $480= $480
Cost = Cost = ∑ ∑∑ ∑ X Xijij C Cijij
nn
i i = 1= 1
nn
j j = 1= 1
Other considerations in Process Layout
For an 8 department problem, there are 8! (or 40,320) possible arrangements.
Factors other than material handling cost are important.
Shipping & Receiving dept cannot be in the center
Sewing cannot be adjacent to Painting
Computer Software
Graphical approach only works for Graphical approach only works for small problemssmall problems
Computer programs are available to Computer programs are available to solve bigger problemssolve bigger problems CRAFT (Computerized Relative CRAFT (Computerized Relative
Allocation of Facilities Technique)Allocation of Facilities Technique)
Process Layout: Systematic Layout Planning Numerical flow of items between departments
– Can be impractical to obtain– Does not account for the qualitative factors that
may be crucial to the placement decision Systematic Layout Planning
– Accounts for the importance of having each department located next to every other department
– Is also guided by trial and error» Switching departments then checking the results of
the “closeness” score
Systematic Layout Planning
10
Systematic Layout Planning--Example: Reasons for Closeness
Code
1
2
3
4
5
6
Reason
Type of customer
Ease of supervision
Common personnel
Contact necessary
Share same price
Psychology
Systematic Layout Planning
Systematic Layout Planning
Systematic Layout Planning
Product LayoutInput Data and Activities
1. Flow of Materials 2. Activity Relationships
3. Relationship Diagram
4. Space Requirements 5. Space Available
6. Space Relationship Diagram
7. Modifying Considerations 8. Practical Limitations
9. Develop Layout Alternatives
10. Evaluation
An
alys
isS
earc
hS
elec
tio
n
Product-Oriented Layout
Equipment is dedicated to a particular product line
Assembly lines are special case of product layout
© 1984-1994 T/Maker Co.
Product Layout
Assembly Lines– A progressive paced assembly linked by some
sort of material handling device. Assembly Line Type Differences
– Material handling devices– Line configuration– Pacing (machine or human)– Product mix– Workstation characteristic– Length of line
Product Layout: Key Terms
Product Interval Time– The time between products being completed (processed
through) at a single station (process step). Also cycle time or takt time.
Product Duration (Throughput) Time.– The overall time required to entirely complete an
individual product.
Assembly Line Balancing– Assignment of tasks to workstations within a given cycle
time and with minimum idle worker time.
Assembly Line Balancing Steps
1. Specify the sequential relationships among tasks using a precedence diagram.
2. Determine the required takt (T) time.
3. Determine the theoretical minimum number of workstations (Nt) required to satisfy the takt time constraint.
4. Select a primary rule by which tasks are to be assigned to workstations and a secondary rule to break ties.
Assembly Line Balancing Steps (cont’d)
5. Assign tasks, one at a time, to the first workstation until the sum of the task times is equal to the takt time. Continue assigning tasks to other workstations until all tasks are assigned.
6. Evaluate the efficiency of the resulting assembly line.
7. If efficiency is unsatisfactory, rebalance the line using a different decision rule in step 4.
Takt Time and Throughput Time on an Assembly Line
Matching task time to takt time:1. Split the task2. Duplicate the station3. Share the task4. Use a more skilled worker5. Work overtime6. Redesign the product
Exhibit 8.9Exhibit 8.9
Assembly Line Balancing Formulas
units)(in day per Output
dayper timeProduction Takt time (T)
Takt time (T)
Sum of task times (S) Number of workstations
Takt time (T)workstations (Na)ofnumber Actual
Sum of task times (S)Efficiency
Assembly Steps and Times for Model J Wagon
Exhibit 8.10Exhibit 8.10
Precedence Graph for Model J Wagon
Exhibit 8.11Exhibit 8.11
A Balance Made According to Largest Number of Following Tasks Rule
Exhibit 8.12aExhibit 8.12a
Precedence Graph for Model J Wagon
Exhibit 8.12BExhibit 8.12B
Efficiency Calculation
Exhibit 8.12CExhibit 8.12C
%77,77.04.505
195orEfficiency
NT
SEfficiency
Flexible Line Layouts
Exhibit 8.13Exhibit 8.13Source: Robert W. Hall, Attaining Manufacturing Excellence (Homewood, IL: Dow Jones-Irwin, 1987), p. 125.
FIGURE 15–4
Improving Layouts by Moving to the Cellular Manufacturing Concept
Source: Source: Barry Render and Jay Heizer, Principles of Operations Management, 2nd ed., © 1997. Reprinted by permission of Prentice Hall, Inc., Upper Saddle River, NJ. G.Dessler, 2003
Group Technology (Cellular) Layout
Benefits– Better human relations in small work teams.– Improved operator expertise from the limited
number of parts and quick production cycle.– Less work-in-process inventory and material
handling due to reduced number of production stages.
– Faster production setup from faster tooling changes.
Group Technology (GT) Layout
Developing a GT Layout– Grouping parts into families that follow a
common sequence of steps.– Identifying dominant flow patterns of parts-
families for location of processes.– Physically grouping machines and processes
into cells.
Facilities Layout for Services
Goals of Service Facility Layouts– Minimize travel time for workers and customers– Maximize revenues from customers
Types of Service Layouts– Process layout—emergency rooms– Product layout—cafeteria line– Fixed-position layout—automobile repair shop
Facilities Layout for Services
Servicescape– The aspects of the physical surroundings in a
service operation that can affect a customer’s perception of the service received.
– Ambient conditions» Noise, lighting, and temperature
– Spatial layout and functionality» Minimizing employee travel time and maximizing
revenue opportunities from customers
– Signs, symbols, and artifacts» Objects that create positive images of the firm
top related