Cell_Manufacturing.ppt

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© 2004 Superfactory™. All Rights Reserved.
Cellular Manufacturing
and Plant Layout
Superfactory Excellence Program™
www.superfactory.com

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(“Superfactory”) are intended for use in training individuals within an organization. The
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are no known copyright issues. Please contact Superfactory immediately if copyright issues
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Outline
 Fundamentals of layout
 Process
 Product
 Fixed
 Hybrid
 Cellular Manufacturing
 Characteristics
 Implementing Cells
 Part Families
 Production Flow Analysis

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What is the Facility Layout Problem?
 Concerned with arrangement of machines, cells, or
departments.
 Often computationally difficult.
 A decision is both quantitative & qualitative.

5
Why is the Layout Problem Difficult?
 It has geometric and combinational aspects.
 Jig-saw puzzle.
 Difficult picture
 No picture
 No shapes
 Goal: Minimize material handling costs.

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Effective Facility Layout
 Minimize material handling costs
 Utilize space efficiently & effectively
 Utilize labor efficiently & effectively
 Eliminate bottlenecks
 Eliminate wasted or redundant movement
 Incorporate safety & security measures

7
Basic Layouts
 There are three basic types of layouts:
 Process
 Product
 Fixed-position
 There are two hybrid types of layouts
 Flexible and Mixed-Model manufacturing systems
 Cellular

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Process Layout
 Process layouts (functional layouts)
 Definition – A layout that groups similar activities
together in departments of work centers according to
process or functions that they perform.

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Characteristics of Process layout
 Goal – To minimize material handling cost
 Product – Varied made to order
 Demand – Fluctuates
 Production volume – low (custom products)
 Inventory – High in process
- Low in finished goods
 Storage Space – relatively large
 Aisles – tend to be wide
 Material handling – variable path (forklift)

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Characteristics
 Layout decision – machine location based
 Workers tend to be skilled at operating the
equipment in their departments
 Intermittent, job shop, batch production, mainly
fabrication

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Process Layout
Lathe Drill
Grind
Lathe Weld
Assembly
Drill
Mill
Warehouse
Lathe Paint
Lathe
Weld
Paint
Mill
Mill
Mill Grind
Assembly
Warehouse

12
Process-Oriented Layout
 Department areas having similar processes located in close
proximity
 Design places departments with large flows of material or
people together

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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

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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

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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
 Inefficient
 Because jobs or customers do not flow through in an orderly
fashion; backtracking is common.
 Idling
 Workers may experience more “idle time” if they are waiting
around for more work to arrive from a different department.

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Impact of Interruptions on Flow Paths
Lathe Drill Grind
Lathe
Drill
Press Bend Drill
Mill Drill
Lathe Mill
Mill
Drill Mill
Drill

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Designing Process Layouts
 The main goal to keep in mind is to minimize material
handling costs
 Therefore the departments that incur the most
interdepartmental movement should be located closest
to one another
 Two types of design layouts
 Block diagramming
 Relationship diagramming

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Block Diagramming
 This refers to the movement of materials in existing or
proposed facility
 Information is usually provided with a from/to chart or
load summary chart
 This gives the average number of units loads moved
between departments

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Block Diagramming
 A unit load can be a single unit, a pallet of material a bin of
material, or a crate of material
 Material is constantly moving from location to location
 The next step is to design the layout by calculating the
composite movements between departments and rank
them from most movement to least movement
 Composite movement refers to the back-and-forth
movement between each pair of departments
 Finally, trial layouts are place on a gird that graphically
represents the relative distances between departments.

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Relationship Diagramming
 For situations in which quantitative date is hard to
obtain it is more relevant to use a relationship
diagramming technique
 Richard Muther developed a format for displaying
manger preferences for departmental locations, know as
Muther’s grid
 Muther’s diagram uses codes and letter to represent
how close departments are to one another
 The information from Muther’s diagram can be used to
make a relationship diagram to evaluate a current
layout or proposed layouts

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Computerized Layout Solutions
 Several computer programs exist that assist in
designing process layouts
 The best known are CRAFT (Computerized Relative
Allocation of Facilities Technique) and CORELAP
(Computerized Relationship Layout Planning)
 Basically the computer program is given layout date
and then makes a recommendation

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Service Layouts
 Most Service organizations use process layouts because
of the variability in customer requests for service
 Service organizations look to maximize profits per unit of
display space, rather than minimize customer flow
 The layout must be aesthetically pleasing we well as
functional

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Process in Manufacturing firms
 Process layouts require flexible material handling
equipment (such as forklifts) which can follow multiple
paths and carry large loads of in-process goods
 All areas of the facility must have timely access to the
material handling equipment

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The Product Layout
 Definition
 A facility layout that arranges activities in a line
according to the sequence of operations that need to be
performed to assemble a product, while minimizing
material handling costs.

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History of the Product Layout
 1895 - Frederick Winslow Taylor.
 Work should be broken into individual tasks.
 Those tasks can be shortened or eliminated.
 Frank Gilbreth - Time study techniques.
 Work combined led to maximum efficiency in industrial
work.

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History
 1909 - Henry Ford
 Boosted recognition for Taylor and Gilbreth’s ideas.
 Increased productivity on his Model T by pulling the car
through the plant at a constant speed while workers
added accumulated parts.
 Production time decreased from 12 hours and 8 minutes
to 1 hour and 33 minutes.

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History
 In the 1920’s manufacturers moved away from assembly
lines to gain flexibility in their products.
 The Product Layout came back into style as a form called
Flow Manufacturing emerged in the 1970’s.
 The Product Layout is still popular today.

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Product Layouts
 Most appropriate for continuous operations.
 Used for products with high volume and steady demand.
 Machines perform a singular, specialized task.
 Machines are organized consecutively.

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Product Layout
Lathe Drill Grind
Lathe
Drill
Press Bend Drill
Mill Drill
Warehouse
Assembly
Lathe Drill

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Product Layout
Shipping
L L M D
L M D
G
L M G
G
A A
Receiving
Part #1
Part #3
Part #2

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Product Requirements
 Standardized product
 High production volume
 Stable production quantities
 Uniform quality of raw materials & components

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Product-Oriented Layout - Assumptions
 Volume is adequate for high equipment utilization
 Product demand is stable enough to justify high investment
in specialized equipment
 Product is standardized or approaching a phase of its life
cycle that justifies investment in specialized equipment
 Supplies of raw materials and components are adequate
and of uniform quality ensure they will work with
specialized equipment

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Product-Oriented Layout Types
Assembly Line
• Assembles fabricated parts
• Uses workstation
• Repetitive process
• Paced by tasks
• Balanced by moving tasks
Fabrication Line
• Builds components
• Uses series of machines
• Repetitive process
• Machine paced
• Balanced by physical redesign

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Line Configuration
 The flow of products is continuous along a line.
 Linear pattern.
 “L” pattern.
 “U” shape.
 Snake shape.
 Shape determines workers flexibility.

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Product Layout - Advantages
 Layout corresponds to the sequence of operations, smooth
and logical flow lines result
 Work from one process is fed directly into the next, small
in-process inventories result
 Total production time per unit is short
 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

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Product Layout - Advantages
 Stable rate of output.
 Work-in-process inventory is low.
 Total production time/unit is reduced.
 Space is effectively utilized.
 Narrow aisles.
 Labor pool is large.
 Single skilled.

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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

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Product Layout - Disadvantages
 If one machine fails the whole process stops.
 Changes in product design can render the layout obsolete.
 Bottlenecks govern the speed.
 Large support staff required.
 High fixed costs.

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Product Layouts - Now & Then
 Traditional
 Top priority: Line
balancing.
 Inventory buffers.
 Planned by admin. staff.
 “L” shaped lines.
 Conveyor movement.
 New Focus
 Top priority: flexibility.
 Preventive maintenance
 Shop supervisor designs
and adjusts.
 “U” shaped lines.
 Stations are close
together.

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Designing Product Layouts
 Main Objective: Arrange workers and machines in a line
according to the operations that need to be performed.
 It isn’t always that simple.
 Line balancing.
 Line balancing software:
 COMSOAL - IBM
 ASYBL - GE

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Line Balancing
 Equalizes amount of work at each station.
 Constraints in Line Balancing.
 Precedence Requirements
 The order in which operations need to take place.
 Cycle Time
 Maximum time a product can be at a station.
 A guess and check process.

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Fixed-Position Layouts
 The product remains stationary for the entire manufacturing
cycle.
 Equipment, workers, materials, and other resources are
brought to the production site.

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When is it used?
Fixed-Position layouts are used in projects in which the product
cannot be moved.
It is typical of projects in which the product produced is:
 too fragile
 bulky
 heavy to move

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 Equipment
 Low equipment utilization:
 idle equipment at location
 it will be needed again in a
few days
 Equipment is leased or
subcontracted
 it is used for limited periods
of time
 Workers
 Highly skilled at performing
special tasks
 High wage rates
 Cost breakdown for fixed-position layouts:
 Fixed Cost:
 relatively low (equipment may
not be owned by the company)
 Variable Cost
 High (due to high labor rates and
the cost of leasing and moving
equipment.
Characteristics of the process:

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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

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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

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Factors Complicating a Fixed Position Layout
 Limited space
 Coordinating service providers in sequence, on time, on
schedule, and with other activities occurring concurrently
 Volume of materials changes often

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Fixed Position Layout
Lathe Grind
Drill
Press
Warehouse
Paint
Warehouse
Assembly

49
Hybrid Layouts
 Flexible & Mixed-Model Manufacturing
 High level of complexity
 Mathematically intensive
 Cellular Manufacturing

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“Cellular Manufacturing organizes the entire process for
similar products into a group of team members,
includes all the necessary equipment and is known as a
"Cell".
Merryman, Wes. Cellular Manufacturing

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“…The cells are arranged to easily facilitate all
operations. Parts are handed off from operation to
operation eliminating setups and unnecessary
costs between operations.”
Merryman, Wes. Cellular Manufacturing

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Introduction to Cellular Manufacturing
• The cellular approach is to organize the entire manufacturing
process for particular or similar products into one group of team
members 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.

53
Introduction to 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.

54
Group Technology / Cellular Layout
Lathe Drill Grind
Lathe
Drill
Press
Warehouse
Assembly
Lathe Drill

55
Work Cells - Advantages
 Increased machine utilization
 Team attitude and job enlargement tend to occur
 Compromise between product layout and process layout, with
associated advantages
 Supports the use of general purpose equipment
 Shorter travel distances and smoother flow lines than for
process layout

56
Work Cells - Advantages
 Reduced work-in-process inventory
 Less floor space required
 Reduced raw material and finished goods inventories required
 Reduced direct labor costs
 Heightened sense of employee participation
 Increased utilization of equipment machinery
 Reduced investment in machinery and equipment

57
Work Cells - Limitations
 General supervision is required
 Higher skill levels required of employees than for product layout
 Compromise between product and process layout, with
associated limitations
 Depends on balanced material flow through the cell; otherwise,
buffers and work-in-process storage are required
 Lower machine utilization than for process layout

58
Empowered Employees in Cells
• Goals and tracking charts are maintained and posted.
• Problems are solved through daily cell meetings and problem
solving teams.
• The inventory management system is a KANBAN Demand Pull
instead of a work order/kit picking system.
• Cells are responsible for planning, scheduling and expediting
directly with vendors.
• They establish and maintain a KANBAN system with the
vendors.

59
Advanced Cellular Manufacturing
 The cell operates like an independent business with total
responsibility for quality, manufacturing and delivery of the
product to the customer.
 All cells have the resources within their organization to
accomplish their mission.
 The requirements are known and goals are established.
 Cell members are flexible and work in teams to accomplish
their goals including continuous improvement.

60
Creating Cells
 First, define the “cells” by the following criteria:
 Processes required
 Part numbers and attributes
 Market segments / customers
 Degree of automation
 Good intuition
 Careful study
 Group Technology (GT)
 Production Flow Analysis (PFA)

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Creating Cells
 Team selection is crucial
 Identify important skills needed such as teamwork and
leadership skills
 Create a process map
 Develop a checklist for selecting members

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Part 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, heat-treated parts,
printed circuit boards)
 How are these groupings determined?
 Coding

63
Finding Part Families
 Visual Inspection of physical parts or photographs to identify similarities.
 Coding and Classification of parts by examining design and/or
manufacturing attributes.
 OPITZ System
 MICLASS System
 Here a code is assigned to specific features of the part.
 Is the part cylindrical or prismatic ?
 Does it have threads?
 Does it have through slots?
 Does it require heat treatment?
 This requires a large initial time investment in coding and classifying all
parts.

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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.

66
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.

67
PFA - Organizational View
Production Flow Analysis consists of 5 different analyses:
1. Company Flow Analysis
2. Factory Flow Analysis
3. Group Analysis
4. Line Analysis
5. Tooling Analysis

68
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.

69
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

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• 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 - Methodology

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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

72
Group Analysis
 Essentially, while forming and rearranging the PFA
matrix 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

73
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.

74
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.

75
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

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 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
PFA: Advantages

77
 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: Weakness

Cell_Manufacturing.ppt

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