Facility Layout In Industrial Engineering 702732
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Facility Layout
What is Facility Layout? Location or arrangement of everything within & around an existing or proposed facility Objective: Efficient flow of work, material, people and information through the system.
Minimize movement and material handling costs
Eliminate wasted or redundant movement
Reduce manufacturing cycle time and customer service time.
Facilitate communication and interaction between customer and other involved in production
Promote product and service quality
Provide flexibility to adept to changing conditions
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
Process Layout in Manufacturing Lathe Department
L
L
L
L
L
L
L
L
L
L
Milling Department
Drilling Department
M
M
D
D
D
D
M
M
D
D
D
D
G
G
G
P
G
G
G
P
Grinding Department Receiving and Shipping
Painting Department
A
A Assembly
A
Lathe
Lathe
Drill
Weld
Weld
Lathe
Lathe
Drill
Paint
Paint
Mill
Mill
Grind
Assembly
Mill
Mill
Grind
Assembly
Warehouse
Warehouse
Process Layout
Process Layout in Services Women’s dresses
Shoes
Housewares
Women’s dresses
Cosmetics and jewelry
Children’s department
Women’s sportswear
Entry and display area
Men’s department
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
A Product Layout In
Out
Lathe
Drill
Grind
Press
Bend
Drill
Mill
Drill
Lathe
Lathe
Drill
Drill
Assembly
Warehouse
Product Layout
Comparison of Product and Process Layouts Product Description
Type of process
Sequential arrangement of activities Continuous, mass production, mainly assembly
Product
Demand Volume Equipment
Process
Functional grouping of activities Intermittent, job shop, batch production, mainly fabrication Standardized, made Varied, made to to stock order Stable Fluctuating High Low Special purpose General purpose
Comparison of Product and Process Layouts Product Workers Inventory
Limited skills Low in-process, high finished goods Storage space Small Material handling Fixed path (conveyor) aisle Narrow (ageway) Scheduling Part of balancing Layout decision Line balancing Goal Equalize work at each station Advantage Efficiency
Process Varied skills High in-process, low finished goods Large Variable path (forklift) Wide Dynamic Machine location Minimize material handling cost Flexibility
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
Fixed-Position Layouts
Fixed Position Layout Press
Grind
Drill
Paint
Assembly
Warehouse
Warehouse
Lathe
Fixed-Position Layouts Typical of projects Equipment, workers, materials, other resources brought to the site Highly skilled labor Often low fixed Typically high variable costs
Product Layout - Advantages Since the layout corresponds to the sequence of operations, smooth and logical flow lines result Since the work from one process is fed directly into the next, small in-process inventories result Total production time per unit is short Since the machines are located as to minimize distances between consecutive operations, material handling is reduced Little skill is usually required by operators at the production line; hence, training is simple, short and inexpensive Simple production planning and control systems are possible Less space is occupied by work in transit and for temporary storage
Lower variable cost per unit
Product Layout - Limitations A breakdown of one machine may lead to complete stoppage of the line that follows that machine Since the layout is determined by the product, a change in product design may require major alterations in the layout The “pace” of production is determined by the slowest machine
Supervision is general Comparatively high investment is required, as identical machines (a few not fully utilized) are sometimes distributed along the line Lack of flexibility
Fixed-Position Layout - Advantages Material movement is reduced Promotes job enlargement by allowing individuals or teams the perform “whole job”
Continuity of operations and responsibility results from team High flexibility; can accommodate changes in product design, product mix, and production volume Independent of production centers allows scheduling to achieve minimum total production time
Fixed-Position Layout - Limitations Increased movement of personnel and equipment Equipment duplication may occur Higher skill requirements for personnel General supervision required Cumbersome and costly positioning of material and machinery
Low equipment utilization
Process Layout - Advantages Better utilization of machines Fewer machines required High degree of flexibility relative to equipment or manpower allocation for specific tasks Comparatively low investment in machines is required The diversity of the task offers a more interesting and satisfying occupation for the operator Specialized supervision is possible
Process Layout - Limitations Since longer flow lines usually result, material handling is more expensive Production planning and control systems are more involved Total production time is usually longer Comparatively large amounts of in-process inventory results Space and capital are tied up by work-in-process Because of the diversity of the jobs in specialized departments, higher grades of skill are required
Types of Layouts High
Product Layout
Group Technology / Cellular Layout
Medium
Low
Fixed Location Layout Low
Process Layout Medium
Variety
High
Deg Process Layouts Goal: minimize material handling costs Block Diagramming minimize nonadjacent loads use when quantitative data is available
Relationship Diagramming based on location preference between areas use when quantitative data is not available
Block Diagramming STEPS create load summary chart quantity in which material is normally calculate composite (two moved way) movements develop trial layouts Nonadjacent load minimizing number of distance farther nonadjacent loads than the next block
Unit load
What is Block Diagramming? Block diagramming is one way to visualize the amount of movement that occurs between departments.
Each block represents one department of a facility. Blocks can be moved around in order to minimize the distance traveled between them.
Example of Block Diagramming Step 1: Gather Information (Department Size) Department
Area Needed (ft2)
1
1000
2
950
3
750
4
1200
5
800
6
700
Total
5400
Example of Block Diagramming (cont.) Step 1: Gather Information (Initial Layout)
2
4
3 60’
6
5 90’
1
Example of Block Diagramming (cont.) Step 1: Gather Information (Trips between departments shown in interdepartmental flow matrix) Department
1
2
1
--
20
2 3 4 5 6
--
3
4
5
20 10 --
6 80
75 15 --
90 70 ---
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show initial traffic) 10
90
2
4 75
6 20
70
5 80
15
3
20
1
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show new traffic) 5
70
75
4
15
20
3 90
20
2
1
80
10
6
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show new layout) 5
4
3 60’
2
1 90’
6
Block Diagramming: Example 2 Load Summary Chart 1
4
2
5
3
FROM/TO
DEPARTMENT
Department 1
2
3
100 —
50 200 —
1 2 3 4 5
— 60
100 50
4 50 40 —
5
50 60 —
Block Diagramming: Example (cont.) 2 2 1 1 4 3 2 3 1 1
3 4 3 2 5 5 5 4 4 5
200 loads 150 loads 110 loads 100 loads 60 loads 50 loads 50 loads 40 loads 0 loads 0 loads
Nonadjacent Loads: 110+40=150 0 110
1
4 Grid 2 1
100
2
150 200
3 4
150 200 50 5050 40 60 110 50 60
3 5
5
40
Block Diagramming: Example (cont.) (a) Initial block diagram
1
(b) Final block diagram
2
4
3
5
1
4 2
3
5
Strengths With correct information, layout efficiency can be improved. Some computer programs can quickly determine optimal solutions.
Weaknesses Sometimes, the data is hard to gather or quantify. Sometimes it is hard to give proper weight to qualitative factors. With many nodes, it is harder to determine optimal solutions.
Relationship Diagramming
Schematic diagram that uses weighted lines to denote location preference Muther’s grid format for displaying manager preferences for department locations
necessary Relationship AE Absolutely Especially important I Important Diagramming: Example O Okay U Unimportant X Undesirable
Production
O A
Offices
U A
U
U
O O
O
A
X U
Locker room Toolroom
E
O
Stockroom Shipping and receiving
I
Relationship Diagrams: Example (cont.) (a) Relationship diagram of original layout
Offices
Stockroom
Locker room
Toolroom
Shipping and receiving
Key: A E I Production O U X
Relationship Diagrams: Example (cont.) (b) Relationship diagram of revised layout
Stockroom
Shipping and receiving
Offices
Toolroom
Production
Locker room
Key: A E I O U X
Systematic Layout Planning
Layout 1. Flow of Materials
2. Activity Relationships
Analysis
Input Data and Activities
3. Relationship Diagram
4. Space Requirements
5. Space Available
7. Modifying Considerations
8. Practical Limitations
Search
6. Space Relationship Diagram
10. Evaluation
Selection
9. Develop Layout Alternatives
Systematic Layout Planning
Systematic Layout Planning
Systematic Layout Planning
Types of Layouts Product - seeks the best personnel and machine use in repetitive or continuous production Fixed-position - large bulky projects such as ships and buildings Group Technology / Cellular – product families Process - deals with low-volume, high-variety production (“job shop”, intermittent production)
Office - positions workers, their equipment, and spaces/offices to provide for movement of information Retail - allocates shelf space and responds to customer behavior Warehouse - addresses trade-offs between space and material handling
Systematic Layout Planning
Computerized layout Solutions CRAFT
Computerized Relative Allocation of Facilities Technique
CORELAP
Computerized Relationship Layout Planning
PROMODEL and EXTEND
visual allow to quickly test a variety of scenarios
Three-D modeling and CAD
integrated layout analysis available in VisFactory and similar software
Deg Service Layouts Must be both attractive and functional Types Free flow layouts
Grid layouts
encourage browsing, increase impulse purchasing, are flexible and visually appealing encourage customer familiarity, are low cost, easy to clean and secure, and good for repeat customers
Loop and Spine layouts
both increase customer sightlines and exposure to products, while encouraging customer to circulate through the entire store
Types of Store Layouts
Deg Product Layouts Objective
Balance the assembly line
Line balancing
tries to equalize the amount of work at each workstation
Precedence requirements
physical restrictions on the order in which operations are performed
Cycle time
maximum amount of time a product is allowed to spend at each workstation
Cycle Time Example
Cd = Cd =
production time available desired units of output
(8 hours x 60 minutes / hour) (120 units)
Cd =
480 120
= 4 minutes
Flow Time vs Cycle Time Cycle time = max time spent at any station Flow time = time to complete all stations 1
2
3
4 minutes
4 minutes
4 minutes
Flow time = 4 + 4 + 4 = 12 minutes Cycle time = max (4, 4, 4) = 4 minutes
Efficiency of Line Efficiency
Minimum number of workstations
i
t i=1
E = nC a
i
t
i
N=
i
i=1
Cd
where
ti j n Ca Cd
= completion time for element i = number of work elements = actual number of workstations = actual cycle time = desired cycle time
Line Balancing Procedure 1. Draw and label a precedence diagram 2. Calculate desired cycle time required for the line 3. Calculate theoretical minimum number of workstations 4. Group elements into workstations, recognizing cycle time and precedence constraints 5. Calculate efficiency of the line 6. Determine if the theoretical minimum number of workstations or an acceptable efficiency level has been reached. If not, go back to step 4.
Line Balancing: Example WORK ELEMENT A B C D
PRECEDENCE
TIME (MIN)
— A A B, C
0.1 0.2 0.4 0.3
Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package 0.2
B 0.1 A
D 0.3 C
0.4
Line Balancing: Example (cont.) WORK ELEMENT A B C D
Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package
PRECEDENCE
TIME (MIN)
— A A B, C
0.1 0.2 0.4 0.3
40 hours x 60 minutes / hour 2400 Cd = = = 0.4 minute 6,000 units 6000 0.1 + 0.2 + 0.3 + 0.4 1.0 N= = = 2.5 3 workstations 0.4 0.4
Line Balancing: Example (cont.) WORKSTATION 1 2 3
ELEMENT
REMAINING TIME
REMAINING ELEMENTS
0.3 0.1 0.0 0.1
B, C C, D D none
A B C D 0.2
Cd = 0.4 N = 2.5
B 0.1 A
D 0.3 C
0.4
Line Balancing: Example (cont.) Work station 1
Work station 2
Work station 3
A, B
C
D
0.3 minute
0.4 minute
0.3 minute
Cd = 0.4 N = 2.5
1.0 0.1 + 0.2 + 0.3 + 0.4 E= = = 0.833 = 83.3% 1.2 3(0.4)
Computerized Line Balancing Use heuristics to assign tasks to workstations
Longest operation time Shortest operation time Most number of following tasks Least number of following tasks Ranked positional weight
Hybrids Layouts Cellular layouts
group dissimilar machines into work centers (called cells) that process families of parts with similar shapes or processing requirements
Flexible manufacturing system
automated machining and material handling systems which can produce an enormous variety of items
Mixed-model assembly line
processes more than one product model in one line
Cellular Layouts 1. Identify families of parts with similar flow paths 2. Group machines into cells based on part families 3. Arrange cells so material movement is minimized 4. Locate large shared machines at point of use
Parts Families
A family of similar parts
A family of related grocery items
Original Process Layout Assembly
4
6
7
8
5 2
A
B
12
10 3
1
9
C
11
Raw materials
Part Routing Matrix Parts
1
2
A B C D E F G H
x
x
Figure 5.8
3
Machines 4 5 6 7
8 9 10 11 12
x
x x
x x
x
x
x
x
x
x
x
x x x x
x
x
x
x x
x
x
x x
x
x x
Revised Cellular Layout Assembly
8
10
9
12
11 4
Cell 1
Cell 2
6
Cell 3 7
2
1
3
A B C Raw materials
5
Reordered Routing Matrix Parts
1
2
4
Machines 8 10 3 6
A D F C G B H E
x x x
x x
x x x
x x x x x x x
x x
9 5
x x x
x
7 11 12
x
x x
x x
x x x x
Direction of part movement within cell
A Manufacturing Cell with Worker Paths
HM
Source: J.T. Black, “Cellular Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983).
VM Worker 3
VM
L Paths of three workers moving within cell Worker 2
Material movement
L
Key: S L HM VM G
G
Final inspection
= Saw = Lathe = Horizontal milling machine = Vertical milling machine = Grinder
S
Worker 1
In
Finished part
Out
Cellular Manufacturing (CM) Product layouts (assembly lines, mass production one a few products on the same line) is the most efficient of the basic layout options Many products are not made in volumes that require a product layout Cellular manufacturing (group technology) – forms families of products that have common production requirements Locate machines, people, jigs, fixtures, drawings, measuring equipment, material handling equipment together (focused factory)
Cellular Manufacturing • The cellular approach is to organize the entire manufacturing process for particular or similar products into one group of team and machines known as a "Cell". • These "cells" are arranged in a U-shaped layout to easily facilitate a variety of operations.
• Parts or assemblies move one at a time (or in small batch sizes). • The parts are handed off from operation to operation without opportunity to build up between operations.
Cellular Manufacturing • Fast setup and quick changeovers are essential to Cellular Manufacturing systems since production runs are shorter. • Setup reduction principles are used to achieve one piece flow and mixed model synchronization. • All cells concentrate on eliminating waste.
Benefits of CM Common tooling required for many products (fewer setups) Tooling can be justified since many products require it (more volume when products are grouped) Minimized material handling Simple production schedule Short cycle time, Low WIP Cross-training – employees operate several machines Minimized material handling costs – since no paperwork is required and distance is small Employees accept more responsibility of supervision (scheduling of parts within cell, scheduling of vacation, purchasing of material, managing a budget) Simple flow pattern and reduced paperwork Buffers are small if batch size is small
Family Formation Various levels – macro and micro Macro – entire factories (focused factories) can specialize in a particular type of part Micro – families can be based on similarities in part geometry (group shafts, flat parts, gears, etc…), process requirements (castings, forgings, sheet metal parts, heattreated parts, printed circuit boards) How are these groupings determined?
Finding Part Families Production Flow Analysis : Since the parts in a part family have similar manufacturing processes, it is possible to identify similar parts by studying the route sheets.
Parts with similar routes can be grouped into families.
Group Analysis To create part families and machine groups a part-machine matrix is created. This is a 0-1 matrix in which a one signifies that a machine is required for a given part. While creating this matrix the machine refers to a "type" of machine. Thus, if there are 5 identical CNC lathes we will create one row in the matrix for these lathes.
Also, the number of times a part visits a machine is not considered at this stage
Group Analysis Once a the part-machine matrix is created, it is customary to remove approximately 10% of the most heavily used machines. Several copies of these machines are likely to be available and thus it is always possible to split these machines between different groups later. The remaining matrix is then inspected for part families.
Group Analysis To identify the part-families the rows and columns are interchanged such that a block-diagonal structure is obtained. There are several algorithms that can be used to do this. A simple algorithm for this problem can be described as follows:
Pick any row and draw a horizontal line through it.
For each 1 in the row that has been crossed once draw a vertical line through the corresponding column.
Pick each new column identified in the previous step. For each 1 in the column that has been crossed once draw a horizontal line through the row.
Repeat this process until there are no singly-crossed 1s in the matrix.
Remove the rows and columns that have been crossed to form a part family-machine group.
Continue for the rest of the matrix
Group Analysis
Problem 2 A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
Thus all parts require all machines and only cell is formed
Automated Manufacturing Cell
Source: J. T. Black, “Cellular Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983)
Advantages and Disadvantages of Cellular Layouts Advantages
Reduced material handling and transit time Reduced setup time Reduced work-inprocess inventory Better use of human resources Easier to control Easier to automate
Disadvantages
Inadequate part families Poorly balanced cells Expanded training and scheduling of workers Increased capital investment
Flexible Manufacturing Systems (FMS) FMS consists of numerous programmable machine tools connected by an automated material handling system and controlled by a common computer network FMS combines flexibility with efficiency FMS layouts differ based on
variety of parts that the system can process size of parts processed average processing time required for part completion
Full-Blown FMS
Mixed Model Assembly Lines Produce multiple models in any order on one assembly line Issues in mixed model lines
Line balancing U-shaped line Flexible workforce Model sequencing
Balancing U-Shaped Lines Precedence diagram:
A
Cycle time = 12 min
B
C
D
E
(a) Balanced for a straight line A,B
C,D
E
9 min
12 min
3 min
Efficiency =
(b) Balanced for a U-shaped line A,B
24 24 = = .6666 = 66.7 % 3(12) 36
C,D
E
Efficiency =
24 24 = = 100 % 12 min 2(12) 24
12 min
What is Facility Layout? Location or arrangement of everything within & around an existing or proposed facility Objective: Efficient flow of work, material, people and information through the system.
Minimize movement and material handling costs
Eliminate wasted or redundant movement
Reduce manufacturing cycle time and customer service time.
Facilitate communication and interaction between customer and other involved in production
Promote product and service quality
Provide flexibility to adept to changing conditions
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
Process Layout in Manufacturing Lathe Department
L
L
L
L
L
L
L
L
L
L
Milling Department
Drilling Department
M
M
D
D
D
D
M
M
D
D
D
D
G
G
G
P
G
G
G
P
Grinding Department Receiving and Shipping
Painting Department
A
A Assembly
A
Lathe
Lathe
Drill
Weld
Weld
Lathe
Lathe
Drill
Paint
Paint
Mill
Mill
Grind
Assembly
Mill
Mill
Grind
Assembly
Warehouse
Warehouse
Process Layout
Process Layout in Services Women’s dresses
Shoes
Housewares
Women’s dresses
Cosmetics and jewelry
Children’s department
Women’s sportswear
Entry and display area
Men’s department
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
A Product Layout In
Out
Lathe
Drill
Grind
Press
Bend
Drill
Mill
Drill
Lathe
Lathe
Drill
Drill
Assembly
Warehouse
Product Layout
Comparison of Product and Process Layouts Product Description
Type of process
Sequential arrangement of activities Continuous, mass production, mainly assembly
Product
Demand Volume Equipment
Process
Functional grouping of activities Intermittent, job shop, batch production, mainly fabrication Standardized, made Varied, made to to stock order Stable Fluctuating High Low Special purpose General purpose
Comparison of Product and Process Layouts Product Workers Inventory
Limited skills Low in-process, high finished goods Storage space Small Material handling Fixed path (conveyor) aisle Narrow (ageway) Scheduling Part of balancing Layout decision Line balancing Goal Equalize work at each station Advantage Efficiency
Process Varied skills High in-process, low finished goods Large Variable path (forklift) Wide Dynamic Machine location Minimize material handling cost Flexibility
Types of Layouts: Basic layouts Process Layout or Functional Layouts: Group similar activities together in departments or work centers according to the process or function they perform.
Product Layouts – Arrange activities in a line according to the sequence of operations that need to be performed to assemble a particular product.
Fixed-position – In this layout, the product remains stationary for the entire manufacturing cycle. Equipment, workers, materials and other resources are brought to the production site.
Fixed-Position Layouts
Fixed Position Layout Press
Grind
Drill
Paint
Assembly
Warehouse
Warehouse
Lathe
Fixed-Position Layouts Typical of projects Equipment, workers, materials, other resources brought to the site Highly skilled labor Often low fixed Typically high variable costs
Product Layout - Advantages Since the layout corresponds to the sequence of operations, smooth and logical flow lines result Since the work from one process is fed directly into the next, small in-process inventories result Total production time per unit is short Since the machines are located as to minimize distances between consecutive operations, material handling is reduced Little skill is usually required by operators at the production line; hence, training is simple, short and inexpensive Simple production planning and control systems are possible Less space is occupied by work in transit and for temporary storage
Lower variable cost per unit
Product Layout - Limitations A breakdown of one machine may lead to complete stoppage of the line that follows that machine Since the layout is determined by the product, a change in product design may require major alterations in the layout The “pace” of production is determined by the slowest machine
Supervision is general Comparatively high investment is required, as identical machines (a few not fully utilized) are sometimes distributed along the line Lack of flexibility
Fixed-Position Layout - Advantages Material movement is reduced Promotes job enlargement by allowing individuals or teams the perform “whole job”
Continuity of operations and responsibility results from team High flexibility; can accommodate changes in product design, product mix, and production volume Independent of production centers allows scheduling to achieve minimum total production time
Fixed-Position Layout - Limitations Increased movement of personnel and equipment Equipment duplication may occur Higher skill requirements for personnel General supervision required Cumbersome and costly positioning of material and machinery
Low equipment utilization
Process Layout - Advantages Better utilization of machines Fewer machines required High degree of flexibility relative to equipment or manpower allocation for specific tasks Comparatively low investment in machines is required The diversity of the task offers a more interesting and satisfying occupation for the operator Specialized supervision is possible
Process Layout - Limitations Since longer flow lines usually result, material handling is more expensive Production planning and control systems are more involved Total production time is usually longer Comparatively large amounts of in-process inventory results Space and capital are tied up by work-in-process Because of the diversity of the jobs in specialized departments, higher grades of skill are required
Types of Layouts High
Product Layout
Group Technology / Cellular Layout
Medium
Low
Fixed Location Layout Low
Process Layout Medium
Variety
High
Deg Process Layouts Goal: minimize material handling costs Block Diagramming minimize nonadjacent loads use when quantitative data is available
Relationship Diagramming based on location preference between areas use when quantitative data is not available
Block Diagramming STEPS create load summary chart quantity in which material is normally calculate composite (two moved way) movements develop trial layouts Nonadjacent load minimizing number of distance farther nonadjacent loads than the next block
Unit load
What is Block Diagramming? Block diagramming is one way to visualize the amount of movement that occurs between departments.
Each block represents one department of a facility. Blocks can be moved around in order to minimize the distance traveled between them.
Example of Block Diagramming Step 1: Gather Information (Department Size) Department
Area Needed (ft2)
1
1000
2
950
3
750
4
1200
5
800
6
700
Total
5400
Example of Block Diagramming (cont.) Step 1: Gather Information (Initial Layout)
2
4
3 60’
6
5 90’
1
Example of Block Diagramming (cont.) Step 1: Gather Information (Trips between departments shown in interdepartmental flow matrix) Department
1
2
1
--
20
2 3 4 5 6
--
3
4
5
20 10 --
6 80
75 15 --
90 70 ---
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show initial traffic) 10
90
2
4 75
6 20
70
5 80
15
3
20
1
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show new traffic) 5
70
75
4
15
20
3 90
20
2
1
80
10
6
Example of Block Diagramming (cont.) Step 2: Develop a block plan (Show new layout) 5
4
3 60’
2
1 90’
6
Block Diagramming: Example 2 Load Summary Chart 1
4
2
5
3
FROM/TO
DEPARTMENT
Department 1
2
3
100 —
50 200 —
1 2 3 4 5
— 60
100 50
4 50 40 —
5
50 60 —
Block Diagramming: Example (cont.) 2 2 1 1 4 3 2 3 1 1
3 4 3 2 5 5 5 4 4 5
200 loads 150 loads 110 loads 100 loads 60 loads 50 loads 50 loads 40 loads 0 loads 0 loads
Nonadjacent Loads: 110+40=150 0 110
1
4 Grid 2 1
100
2
150 200
3 4
150 200 50 5050 40 60 110 50 60
3 5
5
40
Block Diagramming: Example (cont.) (a) Initial block diagram
1
(b) Final block diagram
2
4
3
5
1
4 2
3
5
Strengths With correct information, layout efficiency can be improved. Some computer programs can quickly determine optimal solutions.
Weaknesses Sometimes, the data is hard to gather or quantify. Sometimes it is hard to give proper weight to qualitative factors. With many nodes, it is harder to determine optimal solutions.
Relationship Diagramming
Schematic diagram that uses weighted lines to denote location preference Muther’s grid format for displaying manager preferences for department locations
necessary Relationship AE Absolutely Especially important I Important Diagramming: Example O Okay U Unimportant X Undesirable
Production
O A
Offices
U A
U
U
O O
O
A
X U
Locker room Toolroom
E
O
Stockroom Shipping and receiving
I
Relationship Diagrams: Example (cont.) (a) Relationship diagram of original layout
Offices
Stockroom
Locker room
Toolroom
Shipping and receiving
Key: A E I Production O U X
Relationship Diagrams: Example (cont.) (b) Relationship diagram of revised layout
Stockroom
Shipping and receiving
Offices
Toolroom
Production
Locker room
Key: A E I O U X
Systematic Layout Planning
Layout 1. Flow of Materials
2. Activity Relationships
Analysis
Input Data and Activities
3. Relationship Diagram
4. Space Requirements
5. Space Available
7. Modifying Considerations
8. Practical Limitations
Search
6. Space Relationship Diagram
10. Evaluation
Selection
9. Develop Layout Alternatives
Systematic Layout Planning
Systematic Layout Planning
Systematic Layout Planning
Types of Layouts Product - seeks the best personnel and machine use in repetitive or continuous production Fixed-position - large bulky projects such as ships and buildings Group Technology / Cellular – product families Process - deals with low-volume, high-variety production (“job shop”, intermittent production)
Office - positions workers, their equipment, and spaces/offices to provide for movement of information Retail - allocates shelf space and responds to customer behavior Warehouse - addresses trade-offs between space and material handling
Systematic Layout Planning
Computerized layout Solutions CRAFT
Computerized Relative Allocation of Facilities Technique
CORELAP
Computerized Relationship Layout Planning
PROMODEL and EXTEND
visual allow to quickly test a variety of scenarios
Three-D modeling and CAD
integrated layout analysis available in VisFactory and similar software
Deg Service Layouts Must be both attractive and functional Types Free flow layouts
Grid layouts
encourage browsing, increase impulse purchasing, are flexible and visually appealing encourage customer familiarity, are low cost, easy to clean and secure, and good for repeat customers
Loop and Spine layouts
both increase customer sightlines and exposure to products, while encouraging customer to circulate through the entire store
Types of Store Layouts
Deg Product Layouts Objective
Balance the assembly line
Line balancing
tries to equalize the amount of work at each workstation
Precedence requirements
physical restrictions on the order in which operations are performed
Cycle time
maximum amount of time a product is allowed to spend at each workstation
Cycle Time Example
Cd = Cd =
production time available desired units of output
(8 hours x 60 minutes / hour) (120 units)
Cd =
480 120
= 4 minutes
Flow Time vs Cycle Time Cycle time = max time spent at any station Flow time = time to complete all stations 1
2
3
4 minutes
4 minutes
4 minutes
Flow time = 4 + 4 + 4 = 12 minutes Cycle time = max (4, 4, 4) = 4 minutes
Efficiency of Line Efficiency
Minimum number of workstations
i
t i=1
E = nC a
i
t
i
N=
i
i=1
Cd
where
ti j n Ca Cd
= completion time for element i = number of work elements = actual number of workstations = actual cycle time = desired cycle time
Line Balancing Procedure 1. Draw and label a precedence diagram 2. Calculate desired cycle time required for the line 3. Calculate theoretical minimum number of workstations 4. Group elements into workstations, recognizing cycle time and precedence constraints 5. Calculate efficiency of the line 6. Determine if the theoretical minimum number of workstations or an acceptable efficiency level has been reached. If not, go back to step 4.
Line Balancing: Example WORK ELEMENT A B C D
PRECEDENCE
TIME (MIN)
— A A B, C
0.1 0.2 0.4 0.3
Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package 0.2
B 0.1 A
D 0.3 C
0.4
Line Balancing: Example (cont.) WORK ELEMENT A B C D
Press out sheet of fruit Cut into strips Outline fun shapes Roll up and package
PRECEDENCE
TIME (MIN)
— A A B, C
0.1 0.2 0.4 0.3
40 hours x 60 minutes / hour 2400 Cd = = = 0.4 minute 6,000 units 6000 0.1 + 0.2 + 0.3 + 0.4 1.0 N= = = 2.5 3 workstations 0.4 0.4
Line Balancing: Example (cont.) WORKSTATION 1 2 3
ELEMENT
REMAINING TIME
REMAINING ELEMENTS
0.3 0.1 0.0 0.1
B, C C, D D none
A B C D 0.2
Cd = 0.4 N = 2.5
B 0.1 A
D 0.3 C
0.4
Line Balancing: Example (cont.) Work station 1
Work station 2
Work station 3
A, B
C
D
0.3 minute
0.4 minute
0.3 minute
Cd = 0.4 N = 2.5
1.0 0.1 + 0.2 + 0.3 + 0.4 E= = = 0.833 = 83.3% 1.2 3(0.4)
Computerized Line Balancing Use heuristics to assign tasks to workstations
Longest operation time Shortest operation time Most number of following tasks Least number of following tasks Ranked positional weight
Hybrids Layouts Cellular layouts
group dissimilar machines into work centers (called cells) that process families of parts with similar shapes or processing requirements
Flexible manufacturing system
automated machining and material handling systems which can produce an enormous variety of items
Mixed-model assembly line
processes more than one product model in one line
Cellular Layouts 1. Identify families of parts with similar flow paths 2. Group machines into cells based on part families 3. Arrange cells so material movement is minimized 4. Locate large shared machines at point of use
Parts Families
A family of similar parts
A family of related grocery items
Original Process Layout Assembly
4
6
7
8
5 2
A
B
12
10 3
1
9
C
11
Raw materials
Part Routing Matrix Parts
1
2
A B C D E F G H
x
x
Figure 5.8
3
Machines 4 5 6 7
8 9 10 11 12
x
x x
x x
x
x
x
x
x
x
x
x x x x
x
x
x
x x
x
x
x x
x
x x
Revised Cellular Layout Assembly
8
10
9
12
11 4
Cell 1
Cell 2
6
Cell 3 7
2
1
3
A B C Raw materials
5
Reordered Routing Matrix Parts
1
2
4
Machines 8 10 3 6
A D F C G B H E
x x x
x x
x x x
x x x x x x x
x x
9 5
x x x
x
7 11 12
x
x x
x x
x x x x
Direction of part movement within cell
A Manufacturing Cell with Worker Paths
HM
Source: J.T. Black, “Cellular Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983).
VM Worker 3
VM
L Paths of three workers moving within cell Worker 2
Material movement
L
Key: S L HM VM G
G
Final inspection
= Saw = Lathe = Horizontal milling machine = Vertical milling machine = Grinder
S
Worker 1
In
Finished part
Out
Cellular Manufacturing (CM) Product layouts (assembly lines, mass production one a few products on the same line) is the most efficient of the basic layout options Many products are not made in volumes that require a product layout Cellular manufacturing (group technology) – forms families of products that have common production requirements Locate machines, people, jigs, fixtures, drawings, measuring equipment, material handling equipment together (focused factory)
Cellular Manufacturing • The cellular approach is to organize the entire manufacturing process for particular or similar products into one group of team and machines known as a "Cell". • These "cells" are arranged in a U-shaped layout to easily facilitate a variety of operations.
• Parts or assemblies move one at a time (or in small batch sizes). • The parts are handed off from operation to operation without opportunity to build up between operations.
Cellular Manufacturing • Fast setup and quick changeovers are essential to Cellular Manufacturing systems since production runs are shorter. • Setup reduction principles are used to achieve one piece flow and mixed model synchronization. • All cells concentrate on eliminating waste.
Benefits of CM Common tooling required for many products (fewer setups) Tooling can be justified since many products require it (more volume when products are grouped) Minimized material handling Simple production schedule Short cycle time, Low WIP Cross-training – employees operate several machines Minimized material handling costs – since no paperwork is required and distance is small Employees accept more responsibility of supervision (scheduling of parts within cell, scheduling of vacation, purchasing of material, managing a budget) Simple flow pattern and reduced paperwork Buffers are small if batch size is small
Family Formation Various levels – macro and micro Macro – entire factories (focused factories) can specialize in a particular type of part Micro – families can be based on similarities in part geometry (group shafts, flat parts, gears, etc…), process requirements (castings, forgings, sheet metal parts, heattreated parts, printed circuit boards) How are these groupings determined?
Finding Part Families Production Flow Analysis : Since the parts in a part family have similar manufacturing processes, it is possible to identify similar parts by studying the route sheets.
Parts with similar routes can be grouped into families.
Group Analysis To create part families and machine groups a part-machine matrix is created. This is a 0-1 matrix in which a one signifies that a machine is required for a given part. While creating this matrix the machine refers to a "type" of machine. Thus, if there are 5 identical CNC lathes we will create one row in the matrix for these lathes.
Also, the number of times a part visits a machine is not considered at this stage
Group Analysis Once a the part-machine matrix is created, it is customary to remove approximately 10% of the most heavily used machines. Several copies of these machines are likely to be available and thus it is always possible to split these machines between different groups later. The remaining matrix is then inspected for part families.
Group Analysis To identify the part-families the rows and columns are interchanged such that a block-diagonal structure is obtained. There are several algorithms that can be used to do this. A simple algorithm for this problem can be described as follows:
Pick any row and draw a horizontal line through it.
For each 1 in the row that has been crossed once draw a vertical line through the corresponding column.
Pick each new column identified in the previous step. For each 1 in the column that has been crossed once draw a horizontal line through the row.
Repeat this process until there are no singly-crossed 1s in the matrix.
Remove the rows and columns that have been crossed to form a part family-machine group.
Continue for the rest of the matrix
Group Analysis
Problem 2 A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
A
B
C
D
E
F
1
1
0
0
1
0
1
2
1
1
0
0
1
0
3
1
0
1
0
0
1
4
0
1
0
0
1
0
5
0
0
1
1
0
0
6
0
0
0
0
0
0
Thus all parts require all machines and only cell is formed
Automated Manufacturing Cell
Source: J. T. Black, “Cellular Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983)
Advantages and Disadvantages of Cellular Layouts Advantages
Reduced material handling and transit time Reduced setup time Reduced work-inprocess inventory Better use of human resources Easier to control Easier to automate
Disadvantages
Inadequate part families Poorly balanced cells Expanded training and scheduling of workers Increased capital investment
Flexible Manufacturing Systems (FMS) FMS consists of numerous programmable machine tools connected by an automated material handling system and controlled by a common computer network FMS combines flexibility with efficiency FMS layouts differ based on
variety of parts that the system can process size of parts processed average processing time required for part completion
Full-Blown FMS
Mixed Model Assembly Lines Produce multiple models in any order on one assembly line Issues in mixed model lines
Line balancing U-shaped line Flexible workforce Model sequencing
Balancing U-Shaped Lines Precedence diagram:
A
Cycle time = 12 min
B
C
D
E
(a) Balanced for a straight line A,B
C,D
E
9 min
12 min
3 min
Efficiency =
(b) Balanced for a U-shaped line A,B
24 24 = = .6666 = 66.7 % 3(12) 36
C,D
E
Efficiency =
24 24 = = 100 % 12 min 2(12) 24
12 min
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