1. Cellular Manufacturing
and Facilities Layout
Dr. Richard A. Wysk

2. Outline of Activities Fundamentals of layout
Advantages of various layouts
Creating part families
Economics of Cellular layout
scheduling
setup reduction
Other issues

3. Readings
Chapter 18 of Computer Aided Manufacturing, Wang, H.P., Chang, T.C. and Wysk, R. A., 3rd Edition (2004 expected)
There is no good reference here. The web site is not operational at this time. Hopefully by August 2002, the introductory chapter will be available.

4. 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

5. 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

6. 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
The flow of this presentation is some basic background of factory flow and layout. The advantages of the basic layout are presented and then some characteristics of these systems are provided, I.e., you can not “pull” with a process layout. Cells simplify things by reducing the problem size. There is no detail on how to form cells or organize production control. These will come later.

7. Types of Manufacturing Layout
Process Layout
Product Layout
Cellular Layout

8. FUNCTIONAL LAYOUTS ARE INEFFICIENT
Lathe
Milling
Drilling L L M M D D D D L L M M
Grinding L L M M G G
Assembly L L G G A A
Receiving and
Shipping G G A A
PROCESS-TYPE LAYOUT

9. 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

10. PRODUCT LAYOUT Part #1 L L M D G A A Receiving L M G Part #2 L M D
Shipping
Part #3

11. 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

12. CELLULAR LAYOUT
Cell #2
Cell #1 D D M I D I L
Cell #3 M M L L D M I

13. 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

14. VOLUME VARIETY HIGH FLEXIBILITY TRANSFER PRODUCTION CAPACITY LINE
SPECIAL
SYSTEM
FLEXIBLE
MANUFACTURING
SYSTEM
VOLUME
MANUFACTURING
Cells
STD. AND GEN.
MACHINERY
LOW
HIGH
VARIETY

15. How are Cells Formed Good intuition Careful study
Group Technology (GT)
Production Flow Analysis (PFA)

16. Typical Part Families Items that are made with the same equipment
Items that look alike
A FAMILY OF PARTS

17. PRODUCTION FAMILY

18. 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.

19. 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.

20. Grouping based on geometry or function

21. 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

22. 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

23. Classification & Coding by Examination of Design & Production Data
Many systems have been developed but none is universally applicable and most implementations require some customization
4 slides on this topic

24. Classification & Coding by Examination of Design & Production Data --CLASSIFICATION--
FUNCTIONAL CLASSIFICATION
coding based on part design attributes
coding based on part manufacturing attributes
coding based on a combination of design & manufacturing attributes
Page has the classification of the classification of parts
STRUCTURAL CLASSIFICATION
Hierarchical Structure
Chain Type Structure

25. The Optiz Classification System
Classification & Coding by Examination of Design & Production Data (….contd.)
The Optiz Classification System
12345
6789
ABCD
Form Code:
describes the primary design attributes
Supplementary Code:
manufacturing attributes – dimensions, work material, accuracy, starting work piece shape
Secondary Code:
Identifies production operation type and sequence
Optiz is of Historical Interest as it was one of the first published classification and coding schemes for mechanical parts. Named after H. Optiz of the University of Aachen in Germany
EXAMPLE

26. Classification & Coding by Examination of Design & Production Data (…
Classification & Coding by Examination of Design & Production Data (….contd.)
In the Hierarchical code structure the interpretation of each symbol depends on the value of the preceding symbols
MultiClass: current commercial product, software sold by OIR.
Hierarchical coding structure where the code length can be of up to 30 digits
Very flexible and requires customization. The code is divided into sections: first 18 digits are provided by OIR and the remaining are customized by the customer according to its requirement.
EXAMPLE : Hierarchical Structure
OIR- Organization for Industrial Research

27. Identifying Manufacturing Cells Using Production Flow Analysis

28. 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)

29. Let’s consider 5 parts (n) and 6 machines (m):
m = {Drill1, Drill2, Mill1, Mill2, Vbore1, Vbore2}
= {D1, D2, M1, M2, V1, V2}

30. Operation Routing Summary

31. Create a PFA matrix, Parts Machines = 101 102 103 104 105 Drill 1 1 11 1 1
Drill 1 1
Machines 2
Mill 1 1 1 = 1
Mill 1 1 2 VB 1 1 1 1 VB 1 2

32. King’s Algorithm (Rank Order Clustering)
Step#1
Calculate the total column width for each column
Generate 2i å
" = i j m w 2
Machine# (i)
Part# (j)
101
102
103
104
105 i 2 1 D 1 1 1 2 1 2 D 1 1 4 2 3 M 1 1 1 8 4 1 M 1 1 16 5 2 V 1 1 1 32 6 1 V 1 64 2
(wj)
Done!
Sum: mi,j * 2i 42 52 10 84 42
for each column (wj)

33. #2. If Wj is in ascending order, go to step #3; otherwise, rearrange the columns to make Wj fall in an ascending order.
105
101 D 1 14 2 48 M V 28
103
101
105
102
104 å i V 32 wj 2 10 42 42 52 84
102
103
104

34. å = m 2 w #3. "i, calculate the total row weight, wi Sum: mi,j * 2j
for each row (wi) wi
103
101
105
102
104 D 1 1 1 14 1 D 1 1 48 2 M 1 1 1 14 1 M 1 1 48 2
Generate 2j V 1 1 1 1 28 1 V 32 2 2j 2 4 8 16 32
Done!

35. #4. If wi is in ascending order, stop
#4. If wi is in ascending order, stop. Otherwise, arrange rows to make Wi ascend.
103
101
105
102
104 1 1 1 D 1 1 1 1 M 1 M1 1 1 1 V 1 V1 1 V 2 1 1 D 2 D2 V2 1 1 M 2 V2

36. #5 Stop and make Cells and Part families
103
101
105
102
104 1 1 1 D 1 1 1 1 M 1 1 1 1 V 1 1 V 2 1 1 D 2 1 1 M 2

37. Discussion
Good rectangles mean that you have very distinctive part families
Do Parts no 103, 101, 105 have a distinct code so that a 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?

38. DIRECT CLUSTER ALGORITHM
101
102
103
104
105 w i D 1 1 1 3 1 D 1 1 2 2 M 1 1 1 3 1 M 1 1 2 V 1 1 1 1 4 1 V 1 1 2
Step #1. For I, calculate the total no. of positive cells in row, i

39. Sort rows in descending order of the wi values
101
102
103
104
105 V 1 D M 2 w i 4 3 D1
No Change D2 V1 M2
No Change
Done!

40. Step #2. j, calculate the total # of positive cell in each column, j

41. Sort columns in ascending order.
101
102
103
104
105 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 1 1 2 M 1 2 V 1 2 3 2 3 3 3
Sort Complete!

42. 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
102
101
103
104
105 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 1 1 2 M 1 2 V 1 2
Move Column 105 to the left and push column 104 back

43. 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
102
101
103
105
104 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 1 1 2 M 1 2 V 1 2
Move Columns 101, 103 & 105 to the left and push column 102 back

44. Observe Elements of Row 4
101
103
105
102
104 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 2 1 1 M 2 1 V 2 1
Move Column 102 to the left and push column 101 back

45. Observe Elements of Rows 5 & 6
102
101
103
105
104 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 2 1 1 M 2 1 V 2 1
Move Column 104 to the left and push column 102 back

46. 104
102
101
103
105 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 2 1 1 M 2 1 V 2 1
Step #3 Complete!!

47. 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
104
102
101
103
105 V 1 1 1 1 1 D 1 1 1 1 M 1 1 1 1 D 2 1 1 M 2 1 V 2 1
Move Row D2 upwards and push row D1 down

48. Observe Elements of Column 104
102
101
103
105 V 1 1 1 1 1 D 2 1 1 M 1 1 1 1 D 1 1 1 1 M 2 1 V 2 1
Move Row D2 to the top and push row V1 down

49. Observe Elements of Column 104
102
101
103
105 D 2 1 1 V 1 1 1 1 1 M 1 1 1 1 D 1 1 1 1 M 2 1 V 2 1
Move Rows M2 & V2 upwards and push row V1 down

50. 104
102
101
103
105 D 2 1 1 M 2 1 V 2 1 V 1 1 1 1 1 M 1 1 1 1 D 1 1 1 1
Step #4 Complete!!

51. Step #5. If current matrix is the same as the previous, stop; else to go 3.

52. Identify Cells or potential Cells
104
102
101
103
105 D 2 1 1
Cell #1 M 2 1 V 2 1 V 1 1 1 1 1
Cell #2 M 1 1 1 1 D 1 1 1 1
Part Family #1
Part Family #2

53. Production Flow Analysis -SCOPE-
We 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..)

55. Production Flow Analysis -Organizational View-
Production Flow Analysis consists of 5 different analyses:
Company Flow Analysis
Factory Flow Analysis
Group Analysis
Line Analysis
Tooling Analysis
PFA defined by Prof. Burbidge in 1971

56. 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.

57. Company’s Goals
CFA (Analysis)
We get a SCHEME for the division of products and components, machines and facilities into factory sets

58. 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 )

59. 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

60. Factory Flow Analysis -An Example-

61. 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

62. 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

63. 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.

64. Line Analysis Example

65. 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.

66. 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

67. 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

68. 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

69. Questions?!? Could you use this for a “real-world” problem?
What problems arise from using PFA?