Cellular Manufacturing
and Facilities Layout
Dr. Richard A. Wysk
rwysk@psu.edu
http://www.engr.psu.edu/cim
Outline of Activities
•
•
•
•
Fundamentals of layout
Advantages of various layouts
Creating part families
Economics of Cellular layout
– scheduling
– setup reduction
• Other issues
Readings
• Chapter 18 of Computer Aided Manufacturing, Wang,
H.P., Chang, T.C. and Wysk, R. A., 3rd Edition (2004
expected)
http://www.engr.psu.edu/cim/active/chapter18.pdf
Exercise
Readiness Assessment Test
A.K.A. RAT
AS AN INDIVIDUAL,
Describe what you think a “part family” is.
Describe what you think a “process family” is.
Which is the best way to cluster products in a
manufacturing facility: a) the way a part
looks, b) the function of the part, 3) the way
the part is made. Why?
Open Book / Open Notes
Exercise
Readiness Assessment Test
A.K.A. RAT
AS A TEAM, take 5 minutes
• Compare and discuss the efficiencies and the uses of the
various ways to group “stuff” in a shop.
• Try to chalk out a ‘best practice’.
• List the criterion you used.
Open Book / Open Notes
Objectives
• To apply the principles of flow to a
complex manufacturing system
• To design the layout of process, product
and cellular manufacturing systems
• To form cells in a manufacturing
environment
• To analyze efficiencies of reduced batch
sizes
Types of Manufacturing Layout
• Process Layout
• Product Layout
• Cellular Layout
FUNCTIONAL LAYOUTS ARE INEFFICIENT
Drilling
Milling
Lathe
L
L
M
M
L
L
M
M
D
D
D
D
Grinding
L
L
M
M
Assembly
L
L
A
A
Receiving and
Shipping
A
A
G
G
G
G
G
G
PROCESS-TYPE LAYOUT
Process Layout Characteristics
• Advantages
– Deep knowledge of the process
– Common tooling and fixtures
– Most Flexible -- can produce many different part types
• Disadvantages
–
–
–
–
Spaghetti flow -- everything gets all tangled up
Lots of in-process materials
Hard to control inter-department activities
Can be difficult to automate
PRODUCT LAYOUT
Part #1
L
L
M
D
G
A
Receiving
L
M
G
A
G
Part #2
Part #3
L
M
D
Shipping
Product Layout Characteristics
• Advantages
– Easy to control -- input control
– Minimum material handling -- frequently linked to the
next process
– Minimal in-process materials
– Can be more easily automated
• Disadvantages
– Inflexible -- can only produce one or two parts
– Large setup
– Duplicate tooling is required for all cells
CELLULAR LAYOUT
Cell #2
Cell #1
D
D
M
I
D
I
L
Cell #3
L
L
D
M
M
I
M
Cellular Layout Characteristics
• Advantages
– Control is simplified
– Common tooling and fixtures
– Flexible -- can produce many different part types - a
part family??
• Disadvantages
– Setup ??
– Need to know about many different processes
HIGH
VOLUME
TRANSFER
LINE
SPECIAL
SYSTEM
FLEXIBLE
MANUFACTURING
SYSTEM
MANUFACTURING
Cells
STD. AND GEN.
MACHINERY
LOW
HIGH
VARIETY
How are Cells Formed
•
•
•
•
Good intuition
Careful study
Group Technology (GT)
Production Flow Analysis (PFA)
Typical Part Families
Items that are made with the same equipment
Items that look alike
A FAMILY OF PARTS
PRODUCTION
FAMILY
Items that are made with the same
equipment - Production Flow Analysis
PFA is a technique that uses Operation
Routing Summaries as input. It clusters the
parts that require the same processes. These
parts can then be assembled into a part
family. The processes can be grouped into a
cell to minimize material handling
requirements.
Items that look alike
Most products that look similar are
manufactured using similar production
techniques. If parts are grouped because
they have similar geometry (about the same
size and shape), then they should represent
a part family.
Grouping based on geometry or
function
THREE TECHNIQUES TO FORM PART FAMILIES
1. TACIT JUDGMENT OR VISUAL INSPECTION
• MAY USE PHOTOS OR PART
PRINTS
• UTILIZES SUBJECTIVE
JUDGMENT
2. CLASSIFICATION & CODING BY EXAMINTAION
OF DESIGN & PRODUCTION DATA
• MOST COMMON IN INDUSTRY
• MOST TIME CONSUMING &
COMPLICATED
Cont’d
THREE TECHNIQUES TO FORM PART FAMILIES
3. PRODUCTION FLOW ANALYSIS
• USES INFORMATION CONTAINED
ON THE ROUTE SHEET
(THEREFORE ONLY MFG. INFO)
• PARTS GROUPED BY REQUIRED
PROCESSING
Classification & Coding by Examination of
Design & Production Data
Many systems have been developed but
none is universally applicable and most
implementations require some
customization
Identifying Manufacturing Cells
Using Production Flow Analysis
Production Flow Analysis
• A technique for forming part families based on Operation
Routing Summaries
• Several methods available. We will discuss 2 algorithms for
PFF (Part Family Formation)
Let’s consider 5 parts (n) and 6 machines (m):
n = {101, 102, 103, 104, 105}
m = {Drill1, Drill2, Mill1, Mill2, Vbore1, Vbore2}
= {D1, D2, M1, M2, V1, V2}
Operation Routing Summary
Part No.
101
102
103
104
105
Routing
D1 -M1 - V1
D2 -M2- V1
D1 -M1
M2 - V2 - D2
V1 - M1 - D1
Times (min)
9 - 12 - 14
5 - 11 - 14
7-9
8 - 12 - 5
7 - 10 - 12
Ave. Dem.
100
250
700
100
200
Create a PFA matrix, M
M =
Machines
Parts
Drill1
Drill2
Mill1
Mill2
VB1
VB2
101
1
0
1
0
1
0
102
0
1
0
1
1
0
103
1
0
1
0
0
0
104
0
1
0
1
0
1
105
1
0
1
0
1
0
King’s Algorithm (Rank Order Clustering)
Step#1
Calculate the total column width for each column
Generate 2i
wj =
 2 mi
i
"i
Machine#
1
2
3
4
5
6
(i)
i
Part# (j)
101
102
103
104
105
2
D1
D2
M1
M2
V1
V2
1
0
1
0
1
0
0
1
0
1
1
0
1
0
1
0
0
0
0
1
0
1
0
1
1
0
1
0
1
0
2
4
8
16
32
64
42
52
10
84
42
Sum: mi,j * 2i
for each column (wj)
(wj)
#2.
If Wj is in ascending order, go to step #3; otherwise,
rearrange the columns to make Wj fall in an ascending order.
101
D1
D2
M1
M2
V1
V2
wj
105
103
101
105
102
104
1
0
1
0
0
0
10
1
0
1
0
1
0
42
1
0
1
0
1
0
42
0
1
0
1
1
0
52
0
1
0
1
1
0
84
102
103
104
i
14
48
14
48
28
32
#3. "i, calculate the total row weight, wi
wi =
Generate 2j
D1
D2
M1
M2
V1
V2
2j
2 m
j
"j
ij
Sum: mi,j * 2j
103
101
105
102
104
wi
1
0
1
0
0
0
2
1
0
1
0
1
0
4
1
0
1
0
1
0
8
0
1
0
1
1
0
16
0
1
0
1
1
0
32
14
48
14
48
28
32
for each row (wi)
#4.
If wi is in ascending order, stop. Otherwise, arrange
rows to make Wi ascend.
103
1
1
0
0
0
0
101
1
1
1
0
0
0
105
1
1
1
0
0
0
102
0
0
1
0
1
1
104
0
0
0
1
1
1
D1
M1
V1
V2
D2
M2
V1
V2
M1
D2 V
2
#5 Stop and make Cells and Part families
103
1
1
0
0
0
0
101
1
1
1
0
0
0
105
1
1
1
0
0
0
102
0
0
1
0
1
1
104
0
0
0
1
1
1
D1
M1
V1
V2
D2
M2
Discussion
•
Good rectangles mean that you have very distinctive part families
•
Do Parts no 103, 101, 105 have a distinct code so that a F can be
made to distinguish them from #102, 104.
•
Cell formation
•
Volume / Floor space
•
Size of problems
•
How about King’s algorithm? Will it always work?
•
Are there problems with it?
DIRECT CLUSTER
ALGORITHM
D1
D2
M1
M2
V1
V2
Step #1.
For
101
1
0
1
0
1
0
I,
102
0
1
0
0
1
0
103
1
0
1
0
1
0
104
0
1
0
1
0
1
105
1
0
1
0
1
0
wi
3
2
3
1
4
1
calculate the total no. of positive cells in row, i
wi =
 M ij
all j
Sort rows in descending order of the wi values
D1
V1
D1
D2
V1 M 1
D2
M2
M2
V2
101
1
1
1
0
0
0
3
102
1
0
0
1
0
0
2
103
1
1
1
0
0
0
3
104
0
0
0
1
1
1
3
105
1
1
1
0
0
0
3
wi
4
3
3
2
1
1
1
No Change
No Change
Step #2.
j,
calculate the total # of positive cell in each
column, j
wj =
m
ij
alli
Sort columns in ascending order.
V1
D1
M1
D2
M2
V2
101
1
1
1
0
0
0
102
1
0
0
1
0
0
103
1
1
1
0
0
0
104
0
0
0
1
1
1
105
1
1
1
0
0
0
3
2
3
3
3
Step #3.
For i = 1 to n, move all columns j where mij = 1 to the left
maintaining the order of previous rows.
Observe Elements of Row 1
V1
D1
M1
D2
M2
V2
102
1
0
0
1
0
0
101
1
1
1
0
0
0
103
1
1
1
0
0
0
104
0
0
0
1
1
1
105
1
1
1
0
0
0
Move Column 105 to the left and push column 104 back
For Rows 1,2 & 3: Move the 1’s to the left and push the columns with
the zeroes back
Observe Elements of Rows 2 & 3
V1
D1
M1
D2
M2
V2
102
1
0
0
1
0
0
101
1
1
1
0
0
0
103
1
1
1
0
0
0
105
1
1
1
0
0
0
104
0
0
0
1
1
1
Move Columns 101, 103 & 105 to the left and push column 102 back
Observe Elements of Row 4
V1
D1
M1
D2
M2
V2
101
1
1
1
0
0
0
103
1
1
1
0
0
0
105
1
1
1
0
0
0
102
1
0
0
1
0
0
104
0
0
0
1
1
1
Move Column 102 to the left and push column 101 back
Observe Elements of Rows 5 & 6
V1
D1
M1
D2
M2
V2
102
1
0
0
1
0
0
101
1
1
1
0
0
0
103
1
1
1
0
0
0
105
1
1
1
0
0
0
104
0
0
0
1
1
1
Move Column 104 to the left and push column 102 back
V1
D1
M1
D2
M2
V2
104
0
0
0
1
1
1
102
1
0
0
1
0
0
101
1
1
1
0
0
0
103
1
1
1
0
0
0
105
1
1
1
0
0
0
Step #4.
For j = m to 1, move all rows I, where mij = 1 to
the top maintaining the order of the previous columns, wij
Observe Elements of Columns 101, 103 & 105: No Change can be made!!
Observe Elements of Column 102
V1
D1
M1
D2
M2
V2
104
0
0
0
1
1
1
102
1
0
0
1
0
0
101
1
1
1
0
0
0
103
1
1
1
0
0
0
105
1
1
1
0
0
0
Move Row D2 upwards and push row D1 down
Observe Elements of Column 104
V1
D2
M1
D1
M2
V2
104
0
1
0
0
1
1
102
1
1
0
0
0
0
101
1
0
1
1
0
0
103
1
0
1
1
0
0
105
1
0
1
1
0
0
Move Row D2 to the top and push row V1 down
Observe Elements of Column 104
D2
V1
M1
D1
M2
V2
104
1
0
0
0
1
1
102
1
1
0
0
0
0
101
0
1
1
1
0
0
103
0
1
1
1
0
0
105
0
1
1
1
0
0
Move Rows M2 & V2 upwards and push row V1 down
D2
M2
V2
104
1
1
1
102
1
0
0
101
0
0
0
103
0
0
0
105
0
0
0
V1
M1
D1
0
0
0
1
0
0
1
1
1
1
1
1
1
1
1
Step #5.
If current matrix is the same as the previous, stop; else
to go 3.
Identify Cells or potential Cells
D2
M2
V2
104
1
1
1
102
1
0
0
101
0
0
0
103
0
0
0
105
0
0
0
Cell #1
V1
M1
D1
0
0
0
1
0
0
1
1
1
1
1
1
1
1
1
Cell #2
Part Family #1
Part Family #2
Production Flow Analysis
-SCOPEWe learned two (and probably the most
common) methods/algorithms for
performing a Production Flow Analysis.
There are a host of other algorithms and
methods which are used in Academics and
in the Industry.
(contd..)
Production Flow Analysis
-Organizational ViewProduction Flow Analysis consists of 5 different
analyses:
1. Company Flow Analysis
2. Factory Flow Analysis
3. Group Analysis
4. Line Analysis
5. Tooling Analysis
Company Flow Analysis
• A Planning technique used for the division of large
companies into factory components. It aims to simplify the
flow of materials between factories.
• Uses FROM-TO charts and frequency charts and a flow
analysis (similar to the one discussed in slides 29 – 41).
• Is not a decision making model, but presents data in a way
that decisions can be made based on a company’s goal.
CFA (Analysis)
Company’s
Goals
We get a SCHEME for the division of products and
components, machines and facilities into factory sets
Factory Flow Analysis
An attempt is made at this stage to find major groups
of departments, and major families of components
which can be completely processed in these
departments.
The Goal is to change factories from process
organization to product organization and to
minimize interdepartmental material flow
(Contd.. FFA Methodology )
Factory Flow Analysis
-Methodology• Study and map the existing flow system
• Identify the dominant material flows between shops
(or buildings)
• Determine the Process Route Number (PRN) for each
part
• Analyze the part by PRN.
• Combine closely associated processes at departments
that complete most of the parts they make
• If parts are observed to backtrack then such flows are
eliminated by minor redeployment of equipment
Factory Flow Analysis
-An Example-
Group Analysis
The flows in each of the individual shops
(identified by FFA) are analyzed.
Operation sequences of the parts that are
being produced in a particular shop are
analyzed to identify manufacturing cells.
Loads are calculated for each part family to
obtain the equipment requirements for each
cell
Group Analysis
Essentially, while forming and rearranging the
PFA matrix (slides 29-41) we were
performing Group Analysis.
Those same algorithms are also employed in
PFA activities other than Group Analysis
(namely CFA, FFA etc..)
Choice of algorithm or technique that is best
suited is, for the most part, a problem
specific issue
Line Analysis
A linear or U-layout is designed for the
machines assigned to each cell.
The routings for each part assigned to the cell
and the frequency of use of each routing are
used to develop a cell for:
– Efficient transport, &
– Minimum material handling and travel by
operators.
Line Analysis Example
Tooling Analysis
A Tooling Analysis helps to schedule the cell by
identifying families of parts with similar operation
sequences, tooling and setups.
It seeks to sequence parts on each machine to
sequence all the machines in the cell to reduce
setup times and batch sizes.
This increases available machine capacity on
bottleneck work canters in the cell.
PFA: Assumptions
• Each component is equally important in
terms of cost
• Lot size & its associated cost are not
directly related to grouping procedure
• Routing is assumed to be optimal
PFA: Weakness
PFA is suitable mostly for small sized
applications, but it has difficulties
coping with some large cell formation
problems when the Machine-Part
Matrix becomes more complex
because of problem size
PFA: Advantages
• Reduces flow distances
• Better suited to JIT and “pull” manufacturing
as the overall flow is much straighter
• Simple and Easy to implement
• Experience: Lots of Research and Background
and support software
Questions?!?
Could you use this for a “real-world” problem?
What problems arise from using PFA?