Post on 14-Nov-2014
Facility Layout
Operations Management
P. Kalyanasundaram
What is Facility Layout?
Location or arrangement of everything within & around buildings
Objectives are to maximize Customer/client interaction/satisfaction Utilization of space, equipment, & people Efficient flow of information, material, & people Employee morale & safety
Constraints on Layout Objectives Product design & volume Process equipment & capacity Quality of work life Building & site
Layout Types Fixed-position layout Process-oriented layout Office layout Retail/service layout Warehouse layout Product-oriented layout
Fixed-Position Layout Design is for stationary project Workers & equipment come to site Complicating factors
Limited space at site Changing material needs
Examples Ship building Highway construction
Process-Oriented Layout Design places departments with large flows of
material or people together Dept. areas have similar processes
e.g., All x-ray machines in same area Used with process-focused processes Examples
Hospitals Machine shops
Process Layout+ Allows specialization - focus on one skill
+ Allows economies of scale - worker can watch several machines at once
+ High level of product flexibility
-- Encourages large lot sizes
-- Difficult to incorporate into JIT
-- Makes cross-training difficult
Process-Oriented Layout
Office
Tool Room
Drill Presses
Table Saws
© 1995 Corel Corp.
© 1995 Corel Corp.
Construct ‘from-to-matrix’ Determine space needs for each dept. Develop initial schematic diagram
Determine layout cost, Xij • Cij
By trial-and-error, improve initial layout Prepare detailed plan
Includes factors besides cost
Process-Oriented Layout Steps
50 100 0 0 20
30 50 10 0
20 0 100
50 0
0
From-to-Matrix
5
1 2 3 4 5 6Department
Dept.
1
2
3
4
6
Number of Trips
Process-Oriented Layout ExampleYou work in facilities engineering. You want to find the cost of this layout. The cost of moving 1 load between adjacent dept. is $1. The cost between nonadjacent dept. is $2.
60 ft.
40 ft.
Room 1 Room 2 Room 3
Dept. 1 Dept. 2 Dept. 3
Dept. 4 Dept. 5 Dept. 6
Room 4 Room 5 Room 6
20
100
50 30
50
50
10
20
Schematic Diagram & CostDept. Dept. Cost
1 3 $2001 2 $ 501 6 $ 404 2 $ 504 3 $ 404 5 $ 502 5 $ 102 3 $ 303 6 $100
Total Cost $570
1 2 3
64 5
100
20
30
50 100
50
50
10
20
Schematic Diagram & CostDept. Dept. Cost
1 2 $ 501 3 $1001 6 $ 204 2 $ 504 3 $ 404 5 $ 502 5 $ 102 3 $ 603 6 $100
Total Cost $480
2 1 3
64 5
100
Larger Layout ProblemsMethod works fine for small problems
Larger problems require software CRAFT-tries to minimize material handling
costs Rearrange many large departments to reduce
costs Human “judgement calls” impossible to
computerize
Product-Oriented Layout
Facility organized around product Design minimizes line imbalance
Delay between work stations Types: Fabrication line; assembly line Examples
Auto assembly line Brewery Paper manufacturing.
1 3
2
4
5
Product-Oriented Layout
Office
Belt Conveyor
Operations
Assembles fabricated parts
Uses workstation Repetitive process Paced by tasks Balanced by moving
tasks
Builds components Uses series of
machines Repetitive process Machine paced Balanced by physical
redesign
Product-Oriented Layout TypesFabrication Line Assembly Line
Cellular Layout (Work Cells) Special case of process-oriented layout Consists of different machines brought
together to make a product May be temporary or permanent Example: Assembly line set up to produce
3000 identical parts in a job shop
Work Cell Floor Plan
Office
Tool RoomWork Cell
Saws Drills
Work Cell Advantages
Reduces:
Inventory
Floor space
Direct labor costs
Increases:
Equipment utilization
Employee participation
Quality
Work Cell Layout+ Facilitates cross-training
+ Can easily adjust production volumes
+ Easy to incorporate into JIT
-- Requires higher volumes to justify
-- May require more capital for equipment
Office Layout Example
Relationship Chart
12
3
Ordinary closeness: President (1) & costing (2)
Absolutely necessary: President (1) & secretary (4)
4
I = Important; U = Unimportant
1 PresidentO
2 Costing UA A
3 Engineering IO
4 President’s Secretary
Relationship Chart
A
OE
OU
UU
UU
U
IO
II
IO
UU
UU
UU
UO
UU
I
IU
UEU
IUE
UUA
UA
II
U
U
E
U
34
21
8765
9
10
12
34
56
78
910
Fast-Food Restaurant
IE
UU
UU
OE
EAA
O
12
34
56
X
UU
1 Cooking Burgers
2 Cooking Fries
3 Packing and Storing
4 Drink Dispensers
5 Counter Service
6 Drive-Up Service
I
Example
21
54 6
3
Example
21
54 6
3
Point Scoring System
Assign points for having two items next to each other (including touching corners)A = 16
E = 8
I = 4
O = 1
U = 0
X = -80
Score for Our SolutionTo
From 1 2 3 4 5 6 Total
1 -80 0 0 0 0 -80
2 4 0 0 0 4
3 0 8 8 16
4 16 0 16
5 1 1
Total -43
Retail/Service Layout Design maximizes product exposure to customers,
profitability per square foot Use Closeness ratings to develop service layouts Decision variables
Store flow pattern Allocation of (shelf) space to products
Types Grid design Free-flow design Video
Retail/Service Layout Grid Design
Office CartsCheck-out
Grocery Store
MeatBread
Mil
k
Retail/Service Layout Free-Flow Design
Feature
Display Table
Trans.Counter
Apparel Store
Warehouse Layout Design balances space (cube)
utilization & handling cost Similar to process layout
Items moved between dock & various storage areas
Optimum layout depends on Variety of items
stored No. items picked
© 1995 Corel Corp.
Warehouse Flow
Receiving Shipping
Warehouse Layout
Try to organize storage in such a way that order pickerscan move through the product in a logical and timely manner.
Warehouse Layout
Fastest near the front Fastest within easy reach Bulk storage vs. Single item picking Serpentine vs. oval picking order Restocking: frequency, safety stock Should be designed around the type of
material handling equipment used (like fork-lift trucks, etc)
Cross-Docking Transferring goods
from incoming trucks at receiving docks
to outgoing trucks at shipping docks
Avoids placing goods into storage
In-comingOutgoing
© 1984-1994 T/Maker Co.
© 1995 Corel Corp.
Conclusion Defined facility layout & its objectives Described the 6 types of layout Did load-distance analysis of process layouts Relationship chart & weighting method Defined work cell Stated the retail store flow guidelines Balanced assembly lines
Readiness Assesment Test (RAT)
1. In a layout, work stations are arranged according to the general function they perform without regard to any particular product. a) product, b) process, c) fixed position, d) storage
2. A product layout is more suited to situations where product demand is stable than when it is fluctuating. a) True, b) False
3. Fixed position layouts are used in projects where the product cannot be moved, and therefore equipment, workers, and materials are brought to it. a) True, b) False
4. In general, work-in-process inventory is large for a product layout and small for a process layout. a) True, b) False
5. Which of the following characteristics is associated with process layout? a) stable demand b) less skilled workers c) specialized machinery d) low volume e) product for general market
RAT – Solution 1. In a Process layout, work stations are arranged according to the general
function they perform without regard to any particular product.
2. True. A product layout is more suited to situations where product demand is stable than when it is fluctuating.
3. True. Fixed position layouts are used in projects where the product cannot be moved, and therefore equipment, workers, and materials are brought to it.
4. False. In general, work-in-process inventory is large for a process layout and small for a product layout.
5. Low Volume is associated with process layout.
Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements.
Design Product Layouts: Line Balancing
Cycle time is the maximum time allowed at each workstation tocomplete its set of tasks on a unit.
Cycle Time
D
OT = timecycle = CT
rateoutput Desired= D
dayper timeoperating OT
CT
OT = rateOutput
D
OT = timecycle = CT
rateoutput Desired= D
dayper timeoperating OT
CT
OT = rateOutput
Determine Maximum Output
task timeof sum = t
CT
t)( =N
Determine the Minimum Number of Workstations Required
Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements
A Simple Precedence Diagrama b
c d e
0.1 min.
0.7 min.
1.0 min.
0.5 min. 0.2 min.
Precedence Diagram
Arrange tasks shown in Figure into three workstations. Use a cycle time of 1.0 minute Assign tasks in order of the most number
of followers
Example 1: Assembly Line Balancing
WorkstationTimeRemaining
Eligible AssignTask
RevisedTime Remaining
StationIdle Time
1 1.0
0.9
0.2
a, c
c
none
a
c
-
0.9
0.2
0.2
2 1.0 b b 0.0 0.0
3 1.0
0.5
0.3
d
e
-
d
e
-
0.5
0.3 0.3
0.5
Example 1 Solution
Percent idle time = Idle time per cycle
(N)(CT)
Efficiency = 1 – Percent idle time
Calculate Percent Idle Time
Assign tasks in order of most following tasks.
Count the number of tasks that follow
Assign tasks in order of greatest positional weight.
Positional weight is the sum of each task’s time and the times of all following tasks.
Some Heuristic (intuitive) Rules:Line Balancing Rules
Ranked Positional Weight Heuristic A task is prioritized based on the cumulative assembly
time associated with itself and its successors. Tasks are assigned in this order to the lowest
numbered feasible workstation. Cumulative remaining assembly time constrains the
number of workstations required. Procedure requires computation of positional weight
PW(i) of each task.
Data Known : Two 4 hour-shifts, 4 days a week will be used for
assembly. Each shift receives two 10 minute breaks. Planned production rate of 1500 units/week.
Model Car Production – Example
RPW Procedure - Example
Task Activity Assembly Time
Immediate Predecessor
a Insert Front Axle / Wheels
20 -
b Insert Fan Rod 6 a
c Insert Fan Rod Cover
5 b
d Insert Rear Axle / Wheels
21 -
e Insert Hood to Wheel Frame
8 -
f Glue Windows to top 35 -
g Insert Gear Assembly
15 c, d
h Insert Gear Spacers 10 g
i Secure Front Wheel Frame
15 e, h
j Insert Engine 5 c
k Attach Top 46 f, i, j
l Add Decals 16 k
Example Solution – Cont…
C = 70 Seconds. N = 202/70 = 2.88 workstations (or) 3
unit
minutes17.1
shift
minutes220
day
shifts2
week
days4
Units1500
Week1C
Example SolutionModel Car Precedence Structure
a
d
e
f
b c j
g h
i k l
20
21
8
35
6 5 5
15 10
15 46 16
RPW Procedure - SolutionPositional Weight calculated based on
the precedence structure (previous slide).
PWl = its task time = 16
PWk = tk + PWl = 46+16 = 62
PWj = tj + PWk = 5+62 = 67
Task PW Ranked PW
a 138 1
b 118 3
c 112 4
d 123 2
e 85 8
f 97 6
g 102 5
h 87 7
i 77 9
j 67 10
k 62 11
l 16 12
RPW Solution Cont… Assignment order is given by the rankings. Task a assigned to station 1.
c - ta = 70 – 20 = 50 seconds left in Station 1.
Next Assign task d 50 – 21 = 29 seconds left in Station 1.
j, k, l70, 65, 19, 33
f, h, e, i70, 35, 25, 17, 22
a, d, b, c, g70, 50, 29, 23, 18, 31
TasksTime RemainingStation
Team Exercise Assembly of a product has been divided into elemental tasks suitable for assignment to unskilled workers. Task times and constraints are given below. Solve by RPW Procedure
g14h
e, f6g
c, d7f
b6e
a10d
a6c
-18b
-20a
Immediate Predecessors
TimeTask
Exercise Solution
a
b
d
e
c
f
g h
20
18
6
1010
6
7
6 14
Task PWi Rank
a 63 1
b 44 2
c 33 4
d 37 3
e 26 6
f 27 5
g 20 7
h 14 8Workstation Assigned
TasksRemaining
Time
1 a, d 30, 10, 0
2 b, c, e 30, 12, 6, 0
3 f, g, h 30, 23, 17, 3