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140ME9122 Lean Manufacturing – Unit II
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140ME9122 Lean Manufacturing – Unit II
Unit II
Lean Tools and Methodologies
Problem solving tools – Cause and Effect Diagram, Pareto analysis, FMEA, Work cell and
equipment management tools – Process Mapping, Spaghetti diagram, U shaped Layout,
Poke Yoke, Kanban, Andon, SMED, One Piece Flow, Genechi Genbutsu, Milk run, Visual
work place, Quality at the source Methodologies – Pillars of Lean Manufacturing – Just in
Time, Jidoka, 5S, TPM, Six Sigma, DFMA, Kaizen.
2.1. PROBLEM SOLVING TOOLS
The term problem solving is used in many disciplines, sometimes with different
perspectives, and often with different terminologies. Problems can also be classified into
two different types (ill-defined and well-defined) from which appropriate solutions are to be
made. Ill-defined problems are those that do not have clear goals, solution paths, or
expected solution. Well-defined problems have specific goals, clearly defined solution
paths, and clear expected solutions.
Problem solving is used in when products or processes fail, so corrective action
can be taken to prevent further failures. It can also be applied to a product or process prior
to an actual fail event, i.e., when a potential problem can be predicted and analyzed, and
mitigation applied so the problem never actually occurs. Techniques such as Failure Mode
Effects Analysis can be used to proactively reduce the likelihood of problems occurring.
Problem-solving strategies are the steps that one would use to find the problem(s)
that are in the way to getting to one's own goal. In this cycle one will recognize the
problem, define the problem, develop a strategy to fix the problem, organize the
knowledge of the problem cycle, figure out the resources at the user's disposal, monitor
one's progress, and evaluate the solution for accuracy.
2.2. CAUSE AND EFFECT DIAGRAM
Cause and Effect Analysis was devised by professor Kaoru Ishikawa, a pioneer of
quality management, in the 1960s. The technique was then published in his 1990 book,
"Introduction to Quality Control."
The diagrams are known as Ishikawa Diagrams or Fishbone Diagrams (because a
completed diagram can look like the skeleton of a fish).
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Although it was originally developed as a quality control tool, For instance, this can
be used it to:
Discover the root cause of a problem.
Uncover bottlenecks in processes.
Identify where and why a process isn't working.
Fig.2.1. Cause and Effect Diagram
Causes are usually grouped into major categories to identify these sources of
variation. The categories typically include
People: Anyone involved with the process
Methods: How the process is performed and the specific requirements for doing it,
such as policies, procedures, rules, regulations and laws
Machines: Any equipment, computers, tools, etc. required to accomplish the job
Materials: Raw materials, parts, pens, paper, etc. used to produce the final product
Measurements: Data generated from the process that are used to evaluate its quality
Environment: The conditions, such as location, time, temperature, and culture in which
the process operates
Procedure to create Cause and Effect diagram:1. To create a Cause and Effect Diagram, write the problem to be solved as descriptively as
possible on one side of the work space, then draw the "backbone of the fish", as shown
below. The example we have chosen to illustrate is "Missed Free Throws".
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Fig.2.2. Cause and Effect Diagram – Step 1
2. The next step is to decide how to categorize the causes. There are two basic methods:
a) by function, or
B) by process sequence. The most frequent approach is to categorize by function.
In manufacturing settings the categories are often: Machine, Method, Materials,
Measurement, People, and Environment. In service settings, Machine and Method are
often replaced by Policies (high level decision rules), and Procedures (specific tasks).
In this case, the manufacturing functions as a starting point, less Measurement because
there was no variability experienced from measurements.
Fig.2.3. Cause and Effect Diagram – Step 2
3. That this is not enough detail to identify specific root causes. There are all many
contributors to a problem, so an effective Cause and Effect Diagram will have many
potential causes listed in categories and sub-categories.
The detailed sub-categories can be generated from either or both of two sources:
Brainstorming by group/team members based on prior experiences.
Data collected from check sheets or other sources.
A closely related Cause & Effect analytical tool is the "5-Why" approach, which
states: "Discovery of the true root cause requires answering the question 'Why?' at least
5 times". Additional root causes are added to the fishbone diagram below:
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Fig.2.4. Cause and Effect Diagram – Step 3
4. Cause and Effect Diagram is dependent upon the level of development - moving past
symptoms to the true root cause, and quantifying the relationship between the Primary
Root Causes and the Effect.
5. Analysis to a deeper level by using Regression Analysis Designed Experiments to
quantify. After identify the primary contributors, and hopefully quantify correlation, add that
information to chart, either directly or with foot notes.
2.3. PARETO ANALYSISPareto analysis is a formal technique useful where many possible courses of action
are competing for attention. In essence, the problem-solver estimates the benefit delivered
by each action, then selects a number of the most effective actions that deliver a total
benefit reasonably close to the maximal possible one.
Pareto analysis is a creative way of looking at causes of problems because it helps
stimulate thinking and organize thoughts. However, it can be limited by its exclusion of
possibly important problems which may be small initially, but which grow with time. It
should be combined with other analytical tools such as failure mode and effects
analysis and fault tree analysis for example.
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This technique helps to identify the top portion of causes that need to be addressed
to resolve the majority of problems. Once the predominant causes are identified, then tools
like the Fish-bone Analysis can be used to identify the root causes of the problems.
While it is common to refer to pareto as "80/20" rule, under the assumption that, in
all situations, 20% of causes determine 80% of problems, this ratio is merely a
convenient rule of thumb and is not nor should it be considered immutable law of nature.
The application of the Pareto analysis in risk management allows management to focus on
those risks that have the most impact on the project.
Fig.2.5. Pareto Diagram
Steps to identifying the principal causes using Pareto Analysis:
1. Create a vertical bar chart with causes on the x-axis and count (number of
occurrences) on the y-axis.
2. Arrange the bar chart in descending order of cause importance that is, the cause
with the highest count first.
3. Calculate the cumulative count for each cause in descending order.
4. Calculate the cumulative count percentage for each cause in descending order.
Percentage calculation: {Individual Cause Count} / {Total Causes Count}*100
5. Create a second y-axis with percentages descending in increments of 10 from
100% to 0%.
6. Plot the cumulative count percentage of each cause on the x-axis.
7. Join the points to form a curve.
8. Draw a line at 80% on the y-axis running parallel to the x-axis. Then drop the line at
the point of intersection with the curve on the x-axis. This point on the x-axis
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separates the important causes on the left (vital few) from the less important
causes on the right (trivial many).
Fig.2.6. Pareto Analysis Diagram
Here is a simple example of a Pareto diagram, using sample data showing the
relative frequency of causes for errors on websites. It enables that 20% of cases are
causing 80% of the problems and where efforts should be focussed to achieve the greatest
improvement. In this case, we can see that broken links, spelling errors and missing title
tags should be the focus.
2.4. FMEAFailure modes and effects analysis (FMEA) is a step-by-step approach for
identifying all possible failures in a design, a manufacturing or assembly process, or a
product or service.
“Failure modes” means the ways, or modes, in which something might fail. Failures
are any errors or defects, especially ones that affect the customer, and can be potential or
actual.
“Effects analysis” refers to studying the consequences of those failures.
Failures are prioritized according to how serious their consequences are, how
frequently they occur and how easily they can be detected. The purpose of the FMEA is to
take actions to eliminate or reduce failures, starting with the highest-priority ones. Failure
modes and effects analysis also documents current knowledge and actions about the risks
of failures, for use in continuous improvement. FMEA is used during design to prevent
failures.
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When to use FMEA:
When a process, product or service is being designed or redesigned, after quality function
deployment.
When an existing process, product or service is being applied in a new way.
Before developing control plans for a new or modified process.
When improvement goals are planned for an existing process, product or service.
When analyzing failures of an existing process, product or service.
Periodically throughout the life of the process, product or service
FMEA Procedure:
Fig. 2.7. FMEA format
1. Assemble a cross-functional team of people with diverse knowledge about the process,
product or service and customer needs. Functions often included are: design,
manufacturing, quality, testing, reliability, maintenance, purchasing (and suppliers), sales,
marketing (and customers) and customer service.
2. Identify the scope of the FMEA. Is it for concept, system, design, process or service?
What are the boundaries? How detailed should we be? Use flowcharts to identify the
scope and to make sure every team member understands it in detail.
3. Fill in the identifying information at the top of the FMEA form. Figure 2.7 shows a typical
format. The remaining steps ask for information that will go into the columns of the form.
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4. Determine how serious each effect is. This is the severity rating, or S. Severity is
usually rated on a scale from 1 to 10, where 1 is insignificant and 10 is catastrophic. If a
failure mode has more than one effect, write on the FMEA table only the highest severity
rating for that failure mode.
5. For each failure mode, determine all the potential root causes. Use tools classified
as cause analysis tool, as well as the best knowledge and experience of the team. List all
possible causes for each failure mode on the FMEA form.
6. For each cause, determine the occurrence rating, or O. This rating estimates the
probability of failure occurring for that reason during the lifetime of the scope. Occurrence
is usually rated on a scale from 1 to 10, where 1 is extremely unlikely and 10 is inevitable.
On the FMEA table, list the occurrence rating for each cause.
7. For each cause, identify current process controls. These are tests, procedures or
mechanisms that now have in place to keep failures from reaching the customer. These
controls might prevent the cause from happening, reduce the likelihood that it will happen
or detect failure after the cause has already happened but before the customer is affected.
8. For each control, determine the detection rating, or D. This rating estimates how well the
controls can detect either the cause or its failure mode after they have happened but
before the customer is affected. Detection is usually rated on a scale from 1 to 10, where 1
means the control is absolutely certain to detect the problem and 10 means the control is
certain not to detect the problem (or no control exists). On the FMEA table, list the
detection rating for each cause.
9. (Optional for most industries) Is this failure mode associated with a critical characteristic?
(Critical characteristics are measurements or indicators that reflect safety or compliance
with government regulations and need special controls.) If so, a column labeled
“Classification” receives a Y or N to show whether special controls are needed. Usually,
critical characteristics have a severity of 9 or 10 and occurrence and detection ratings
above 3.
10. Calculate the risk priority number, or RPN, which equals S × O × D. Also calculate
Criticality by multiplying severity by occurrence, S × O. These numbers provide guidance for
ranking potential failures in the order they should be addressed.
11. Identify recommended actions. These actions may be design or process changes to lower
severity or occurrence. They may be additional controls to improve detection. Also note who
is responsible for the actions and target completion dates.
12. As actions are completed, note results and the date on the FMEA form. Also, note new
S, O or D ratings and new RPNs.
2.5. WORK CELL
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A work cell is an arrangement of resources in a manufacturing environment to
improve the quality, speed and cost of the process. Work cells are designed to improve
these by improving process flow and eliminating waste. Lean work cells must be designed
for minimal wasted motion, which refers to any unnecessary time and effort required to
assemble a product. Excessive twists or turns, uncomfortable reaches or pickups, and
unnecessary walking all contribute to wasted motion and may put error
inducing stress upon the operator. Work cells can often be reconfigured easily to allow the
adaptation of the process to fit takt time. This flexibility allows the work content to be
adapted as demand or product mix changes.
Fig. 2.8. Work Cell
A work cell is a work unit larger than an individual machine or workstation but
smaller than the usual department. Typically, it has 3-12 people and 5-15 workstations in a
compact arrangement. An ideal cell manufactures a narrow range of highly similar
products. Such an ideal cell is self-contained with all necessary equipment and resources.
Work cell layouts organize departments around a product or a narrow range of
similar products. Materials sit in an initial queue when they enter the department. Once
processing begins, they move directly from process to process. The result is very fast
throughput. Communication is easy since every operator is close to the others. This
improves quality and coordination. Proximity and a common mission enhance teamwork.
U- Shaped Layout
Fig. 2.8. U shaped Work Cell
2.6. EQUIPMENT TOOLS MANAGEMENT
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Tools have a tendency to be issued from their storage location to the point-of-use
on the shop floor. Once issued and used, the tool may return to its original storage
location, stay at the usage location, remain as a dedicated tool or be discarded. However,
over the course of time, the tool will ideally find its way back to its original issue location.
When that happens, decisions are made concerning its usable condition.
It's reusable as is - return it to a storage location.
It needs reconditioning, so send it out for repair or resharpen it.
It is un-repairable - discard it.
The following ten rules will provide the foundation upon which a successful tool
management system can be built.
1. Control the access to the crib. Put a lock on the door.
2. Organize the storage cabinets, shelves or shoeboxes that are used to store the tooling.
Give the locations names, tags or some sequence of identification - numeric, alphabetical
or both.
3. Insist that all tooling issued and returned be recorded through the system. This insures a
higher degree of accuracy.
4. The crib personnel should know more about how the tooling is issued than anyone else
and can provide information critical to the building of the tool database.
5. Train all tool crib personnel. Provide at least two competent system administrators for
overall system control.
6. Establish guidelines for the return of tools to the crib for rework consideration, for the
scrapping of a tool or to return the tool to its original or used location.
7. Review your purchasing procedures. Hold a joint meeting with all personnel involved in
the requisitioning and purchasing of tooling.
8. Establish rules for defining what are durable tools and if they are expected to be
returned to the tool crib. A suggested guideline could be as follows:
Perishable tools can be consumed by use; i.e., drills, end-mills, taps, carbide
inserts, etc.
Durable tools are generally not consumed by use; i.e., toolholders, collets, dies,
micrometers, fixtures and power tools.
Returnable tools are expected to be returned to the crib after use
Non-returnable tools are not required to be returned to the crib after use or tools
that are permanently assigned to a department/ machine or employee.
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9. Establish rules for reordering perishable and durable tools. A suggested guideline could
be as follows:
For perishable tools - reorder when the total quantity of tools in the crib inventory is
below the defined minimum quantity.
For durable tools - reorder when the total on-hand quantity of tools is below the
defined minimum quantity.
10. Agree on a tool numbering system and stick to it. All tooling items must have a discrete
and individual identification to distinguish one item type from another. Establish a group to
be responsible for the implementation and maintenance of the numbering procedure.
Basic Features for Tool Management
Tool/part number.
Description.
Price.
Quantity requirements.
Where used by shop floor, machines, jobs and users.
Minimum/maximum inventory levels.
Reorder point.
Vendor information.
Lead times.
Custom and standard reports.
Tool storage stations.
Tool issue tracking by employee, date, job and profit center/machine.
Support transactions.
Ease of use.
Process new and regrind tool activities.
Tool tracking cross-reference.
Tool availability.
Status reports.
Ordering reports.
Basic inventory information reports.
History information.
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2.7. PROCESS MAPPINGA process map is a planning and management tool that visually describes the flow
of work. Process maps show a series of events that produce an end result. A process map
is also called a flowchart, process flowchart, process chart, functional process chart,
functional flowchart, process model, workflow diagram, business flow diagram or process
flow diagram. It shows who and what is involved in a process and can be used in any
business or organization and can reveal areas where a process should be improved.
Purpose of process mapping:The purpose of process mapping is for organizations and businesses to improve
efficiency. Process maps provide insight into a process, help teams brainstorm ideas for
process improvement, increase communication and provide process documentation.
Process mapping will identify bottlenecks, repetition and delays. They help to define
process boundaries, process ownership, process responsibilities and effectiveness
measures or process metrics.
One of the purposes of process mapping is to gain better understanding of a
process. The flowchart below is a good example of using process mapping to understand
and improve a process. In this chart, the process is making pasta. Even though this is a
very simplified process map example, many parts of business use similar diagrams to
understand processes and improve process efficiency, such as operations, finance, supply
chain, sales, marketing and accounting.
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Fig. 2.8. Sample Process Mapping
Benefits of process mapping:Process mapping spotlights waste, streamlines work processes and builds
understanding. Process mapping allows to visually communicate the important details of a
process rather than writing extensive directions.
Increase understanding of a process
Analyze how a process could be improved
Show others how a process is done
Improve communication between individuals engaged in the same process
Provide process documentation
Plan projects
Process mapping symbols:Key elements of process mapping include actions, activity steps, decision points,
functions, inputs/outputs, people involved, process measurements and time required.
Basic symbols are used in a process map to describe key process elements. Each process
element is represented by a specific symbol such as an arrow, circle, diamond, box, oval
or rectangle. These symbols come from the Unified Modeling Language or UML, which
is an international standard for drawing process maps.
Fig. 2.9. Process mapping symbols
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How to create a process map: Step 1: Identify the problem
What is the process that needs to be visualized?
Type its title at the top of the document.
Step 2: Brainstorm activities involved
At this point, sequencing the steps isn’t important, but it may help to remember the
steps needed for the process.
Decide what level of detail to include.
Determine who does what and when it is done.
Step 3: Figure out boundaries
Where or when does the process start?
Where or when does the process stop?
Step 4: Determine and sequence the steps
It’s helpful to have a verb begin the description.
It can show either the general flow or every detailed action or decision.
Step 5: Draw basic flowchart symbols
Each element in a process map is represented by a specific flowchart symbol.
Ovals show the beginning of a process or the stopping of a process.
Rectangles show an operation or activity that needs to be done.
Arrows represent the flow of direction.
Diamonds show a point where a decision must be made.
A parallelogram shows inputs or outputs.
Step 6: Finalize the process flowchart
Review the flowchart with others stakeholders (team member, workers,
supervisors, suppliers, customers, etc.) for consensus.
Types of process mapping:
Activity Process Map: represents value added and non-value added activities in a
process
Detailed Process Map: provides a much more detailed look at each step in the
process
Document Map: documents are the inputs and outputs in a process
High-Level Process Map: high-level representation of a process involving
interactions between Supplier, Input, Process, Output, Customer (SIPOC)
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Rendered Process Map: represents current state and/or future state processes to
show areas for process improvement
Cross-functional Map: separates out the sub-process responsibilities in the
process
Value-Added Chain Diagram: unconnected boxes that represent a very simplified
version of a process for quick understanding
Value Stream Map: a lean-management technique that analyzes and improves
processes needed to make a product or provide a service to a customer.
Work Flow Diagram: a work process shown in “flow” format; doesn’t utilize Unified
Modeling Language (UML) symbols.
2.8. SPAGHETTI DIAGRAMA spaghetti diagram is a visual representation using a continuous flow line tracing
the path of an item or activity through a process. The continuous flow line enables process
teams to identify redundancies in the work flow and opportunities to expedite process flow.
Fig. 2.10. Spaghetti diagram
The diagram in the figure 2.10. reflects a study done by a health department
administrative office. The intent of the study was to identify ways to shorten the walking
time from one activity to another for frequently performed tasks.
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Another benefit of the visual drawing is to highlight major intersection points within
the room. Areas where many walk paths overlap are causes of delay. Waiting is one of
the eight wastes of lean, as is unnecessary motion.
Collaboration of the staff most affected by the current workplace design was a
secondary benefit of creating the spaghetti diagram. The health department quality
improvement coordinator facilitated a brainstorming session to identify areas of congestion
and wasted movement among the office personnel. Focusing on a common goal brought
the team closer together while highlighting the purpose for placement of some work areas.
These diagrams are used to track:
1. Product Flow
2. Paper Flow
3. People Flow
Use a different line type or color for each flow type, or use separate map for each
flow path for more clarity. Creating a Spaghetti Diagram should be done with or by the
operators or those that use the process. Record the path with a pencil and use a
measuring wheel or tape measure to document distances.
STEPS:1) Record the processes on the side and ask questions if not clear on the activity.
2) Start at the beginning of the scope, the start of the first process. Use directional arrows
for the routes that are traced on the paper.
3) Do not leave out any flow movement
4) Record the amount of time within each activity.
5) Shows the areas where materials stops, staged, held, inspected and picked up. Look for
point-of-use opportunities for materials, tools, and paperwork.
6) Record the names of those involved, dates, times, and other relevant information.
7) Calculate the distance, times, shift, starts, stops, to provide baseline performance.
8) Create a separate diagram showing the ideal state of flow for each that eliminates as
much non-value added tasks as possible.
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Fig. 2.10. Spaghetti diagram – Before & After
2.9. U SHAPED LAYOUTGenerally a U-Shaped work area layout that enables workers to easily move from
one process to another in close proximity and pass parts between workers with little effort.
Cellular manufacturing involves the use of multiple "cells" in an assembly line fashion.
Each of these cells is composed of one or multiple different machines which accomplish a
certain task. The product moves from one cell to the next, each station completing part of
the manufacturing process. Often the cells are arranged in a "U-shape" design because
this allows for the overseer to move less and have the ability to more readily watch over
the entire process.
Fig. 2.11. U shape layout
The layout of work cells in a U shape has several advantages:
The IN and OUT are close, allowing visual control and management, according to
the production takt, a single person can handle both the cell input feeding and
output
The shortening of distances allow sharing of work, as well as reduction of
transportation waste
These layouts provide convenient foundation for one piece flow
Communication among team mates in the cell is easier
The work is done inside the U, supplies remain outside
Usually machines and tables are on rollers (if possible) for quick reconfiguration
The floor space is generally fewer with a U cell than stretched line, walk distances
are also reduced.
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2.10. POKE YOKEPoka Yoke or Mistake proofing is a simple technique that developed out of the
Toyota Production system through Jidoka and Autonomation. It is normally a simple and
often inexpensive device that prevents defects from being made or highlights a defect so
that it is not passed to the next operation.
Purpose of Poka Yoke:
To overcome the inefficiencies of inspection through the use of automatic devices
called Poka Yoke, these seek to do three things;
Not accept a defect for the process
Not Create a Defect
Not Allow a Defect to be passed to the next process
Poka Yoke can be categorized as:
Control – they take physical action to prevent a defect
Warning – They sound an alarm or light up to tell us a mistake has been made.
Types of Poka Yoke:
1. Contact Poka Yoke
Fig. 2.12. Contact Poka Yoke
Contact type Poka Yoke devices that have physical shapes that are used to
prevent the use of incorrect components, pins that have to fit into holes from previous
operations and so on, they physically make contact with the product and highlight when a
mistake has been made or physically make it impossible to make the mistake.
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2. Fixed Value Pokayoke
Fig. 2.13. Fixed Value Poka Yoke
Fixed Value Pokayoke is a method that uses physical and visual methods to
highlight that all components are available in the right quantities and have been used,
sometimes combined with contact style sensors to make them more positive. Pre-dosed
medication in a sachet rather than relying on the user to measure from a larger container.
3. Motion Stop pokayoke
Fig. 2.14. Motion Stop Poka Yoke
Motion Stop Poka yoke device ensures that the correct number of steps have been
taken and possibly also the sequence steps. Example this could be the use of a nut runner
to tighten a specific number of bolts to a required torque. If the correct torque is not
reached of if the operator not tighten all of the bolts the part will not be released to the next
operation.
2.11.KANBANKanban is an inventory-control system to control the supply chain. Taiichi Ohno,
an at Toyota, developed kanban to improve manufacturing efficiency. Kanban is one
method to achieve JIT.
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Kanban became an effective tool to support running a production system as a
whole, and an excellent way to promote improvement. Problem areas are highlighted by
reducing the number of kanban in circulation. One of the main benefits of kanban is to
establish an upper limit to the work in process inventory, avoiding overloading of the
manufacturing system.
Toyota started studying supermarkets with the idea of applying shelf-stocking
techniques to the factory floor. Kanban aligns inventory levels with actual consumption. A
signal tells a supplier to produce and deliver a new shipment when material is consumed.
These signals are tracked through the replenishment cycle, bringing visibility to the
supplier, consumer, and buyer. Kanban uses the rate of demand to control the rate of
production, passing demand from the end customer up through the chain of customer-
store processes.
Fig. 2.15. Kanban system
Toyota has formulated six rules for the application of kanban: Later process picks up the number of items indicated by the kanban at the earlier
process.
Earlier process produces items in the quantity and sequence indicated by the kanban.
No items are made or transported without a kanban.
Always attach a kanban to the goods.
Defective products are not sent on to the subsequent process. The result is 100%
defect-free goods.
Reducing the number of kanban increases the sensitivity.
Types of Kanban systems:
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In a kanban system, adjacent upstream and downstream workstations
communicate with each other through their cards, where each container has a kanban
associated with it. Economic Order Quantity is important. The two most important types of
kanbans are:
Production (P) Kanban: A P-kanban, when received, authorizes the workstation to
produce a fixed amount of products. The P-kanban is carried on the containers that
are associated with it.
Transportation (T) Kanban: A T-kanban authorizes the transportation of the full
container to the downstream workstation. The T-kanban is also carried on the
containers that are associated with the transportation to move through the loop again.
Kanban cards:
Fig. 2.16. Kanban card
Kanban cards are a key component of kanban and they signal the need to move
materials within a production facility or to move materials from an outside supplier into the
production facility. The kanban card is, in effect, a message that signals depletion of
product, parts, or inventory. When received, the kanban triggers replenishment of that
product, part, or inventory. Consumption, therefore, drives demand for more production,
and the kanban card signals demand for more product — so kanban cards help create a
demand-driven system.
It is widely held by proponents of lean production and manufacturing that demand-
driven systems lead to faster turnarounds in production and lower inventory levels, helping
companies implementing such systems be more competitive.
2.12. ANDON
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Andon is a manufacturing term referring to a system to notify management,
maintenance, and other workers of a quality or process problem. The centre piece is a
device incorporating signal lights to indicate which workstation has the problem. The alert
can be activated manually by a worker using a pull cord or button, or may be activated
automatically by the production equipment itself. The system may include a means to stop
production so the issue can be corrected. Some modern alert systems incorporate audio
alarms, text, or other displays.
Fig. 2.17. Anodon
An Andon System is one of the principal elements of the Jidoka quality-
control method as part of the Toyota Production System. Andon gives the worker the
ability, and moreover the empowerment, to stop production when a defect is found, and
immediately call for assistance. Work is stopped until a solution has been found. The alerts
may be logged to a database so that they can be studied as part of a continuous-
improvement program.
The system typically indicates where the alert was generated, and may also
provide a description of the trouble. Modern Andon systems can include text, graphics, or
audio elements. Audio alerts may be done with coded tones, music with different tunes
corresponding to the various alerts, or pre-recorded verbal messages.
Fig. 2.18. Modern Andon systems
2.13. SMED
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Single-Minute Exchange of Die (SMED) is one of the many lean
production methods for reducing waste in a manufacturing process. It provides a rapid and
efficient way of converting a manufacturing process from running the current product to
running the next product. This rapid changeover is key to reducing production lot sizes and
thereby improving flow, reducing production loss and output variability. The phrase "single
minute" does not mean that all changeovers and start ups should take only one minute,
but that they should take less than 10.
Shigeo Shingo, who created the SMED approach, claims that in his data from
between 1975 and 1985 that average setup times he has dealt with have reduced to 2.5%
of the time originally required; a 40 times improvement.
Shigeo Shingo recognizes eight techniques that should be considered in implementing
SMED.
1. Separate internal from external setup operations
2. Convert internal to external setup
3. Standardize function, not shape
4. Use functional clamps or eliminate fasteners altogether
5. Use intermediate jigs
6. Adopt parallel operations
7. Eliminate adjustments
8. Mechanization
Fig. 2.19. SMED - Adopt parallel operations
Seven basic steps to reducing changeover using the SMED system (Fig 2.19):1. OBSERVE the current methodology (A)
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2. Separate the INTERNAL and EXTERNAL activities (B). Internal activities are those
that can only be performed when the process is stopped, while External activities
can be done while the last batch is being produced, or once the next batch has
started. For example, go and get the required tools for the job BEFORE the
machine stops.
3. Convert (where possible) Internal activities into External ones (C) (pre-heating of
tools is a good example of this).
4. Streamline the remaining internal activities, by simplifying them (D). Focus on
fixings - Shigeo Shingo observed that it's only the last turn of a bolt that tightens it -
the rest is just movement.
5. Streamline the External activities, so that they are of a similar scale to the Internal
ones (D).
6. Document the new procedure, and actions that are yet to be completed.
7. Do it all again: For each iteration of the above process, a 45% improvement in set-
up times should be expected, so it may take several iterations to cross the ten-
minute line.
SMED improvement should pass through four conceptual stages:A) ensure that external setup actions are performed while the machine is still running,
B) separate external and internal setup actions, ensure that the parts all function and
implement efficient ways of transporting the die and other parts,
C) convert internal setup actions to external,
D) improve all setup actions.
Stages of SMED:
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Fig. 2.19. Stages of SMED
Example of SMED:
Fig. 2.20. Example of SMED
2.14. ONE PIECE FLOW
Fig. 2.20. One piece flow
One-piece flow is a technique used to manufacture components in a cellular
environment. The cell is an area where everything that is needed to process the part is
within easy reach, and no part is allowed to go to the next operation until the previous
operation has been completed. The goals of one piece flow are: to make one part at a time
correctly all the time to achieve this without unplanned interruptions to achieve this without
lengthy queue times.
Basic condition for achieving one-piece flow:i. Processes must be able to consistently produce good product. If there are many quality
issues, one-piece flow is impossible.
ii. Process times must be repeatable as well. If there is much variation, one-piece flow is
impossible.
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iii. Equipment must have very high uptime. Equipment must always be available to run. If
equipment within a manufacturing cell is plagued with downtime, one piece flow will be
impossible.
iv. Processes must be able to be scaled to tact time, or the rate of customer demand. For
example, if tact time is 10 minutes, processes should be able to scale to run at one unit
every 10 minutes.
Implementing one-piece flow:The first step in implementing a one-piece flow cell is to decide which products or
product families will go into the cells, and determine the type of cell: Product-focused or
mixed model.
The next step is to calculate tact time for the set of products that will go into the cell.
Tact time is a measure of customer demand expressed in units of time and is calculated as
follows:
Tact time = Available work-time per shift / Customer demand per shift.
Next, determine the work elements and time required for making one piece. In much
detail, list each step and its associated time. Time each step separately several times and
use the lowest repeatable time. Then, determine if the equipment to be used within the cell
can meet tact time.
Finally, balance the cell and create standardized work for each operator within the
cell. Determine how many operators are needed to meet tact time and then split the work
between operators. Use the following equation:
Number of operators = Total work content / Tact time
The following illustration shows the impact of batch size reduction when comparing batch
and-queue and one-piece flow.
Fig. 2.21. Batch process Vs One piece flow
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2.15. GENCHI GEMBUTSUGenchi gembutsu is a Japanese phrase that translates in English to “go and see for
yourself” is a central tenet of the Toyota Production System.
Key principle in the Toyota Production System
Go and look out for yourself
Facilitates early contact with potential customers
Increase the chance that actual issues and unplanned events will be observed first
hand.
Fig. 2.22. Genchi Gembutsu
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The idea behind genchi gembutsu is that business decisions need to be based on
first-hand knowledge, not the understanding of another person which might be biased,
outdated or incorrect. Problems are best understood and solved where they occur -– for
example, on the factory floor. Rather than looking at information from a distance –- in an
office, for example –- regarding process issues, managers should go see for themselves
what is happening.
2.16. MILK RUN
Fig. 2.23. Milk run
A method to speed the flow of materials between facilities by routing vehicles to
make multiple pick-ups and drop-offs at many facilities. By making frequent pick-ups and
drop-offs with milk-run vehicles connecting a number of facilities rather than waiting to
accumulate a truckload for direct shipment between two facilities, it is possible to reduce
inventories and response times along a value stream. Milk runs between facilities are
similar in concept to material handling routes within facilities.
Fig. 2.24. Milk run - Example
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2.17. VISUAL WORK PLACE
Visual workplace, visual devices are positioned at the point of use, giving
employees instant access to the critical information they need, right when they need it.
Visuals can easily be understood at a glance, eliminating the wasted downtime that had
previously been spent searching, asking, or waiting for information. This model can greatly
improve your productivity, cost, quality, on-time delivery, inventory and equipment
reliability.
Fig. 2.25. Visual Workplace
Visuals reinforce standards and highlight abnormalities. This is especially important
during the initial phase of lean when companies are using concepts such as 5S, Standard
Work, and Total Productive Maintenance to create a base of operational stability.
A continuously improving work environment is a constantly changing one. Gains
from 5S Workplace Organization, Total Productive Maintenance (TPM), Kaizen
(Continuous Improvement) and other lean activities will disappear unless the new best
practices are embedded in the workplace. Visuals ensure lean improvements remain
clearly visible, readily understood, and consistently adhered to long after the kaizen
improvement event is over – and prevent employees from reverting to old habits.
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Visual controls:
Fig. 2.26. Visual Management
Visual controls allow us to communicate without words and share information
without interrupting. It helps to get everyone working together by providing a clear
understanding of what is required at that point in time. Visual controls contribute to the
management of every process in a way that individuals alone are not able to do, by
showing where discrepancies occur. As with many of the lean enterprise principles we
need to put systems in place to easily identify when things are going well so don’t need to
worry about them. This allows us, and our management team, to easily assess the
situation across the factory and know when we need to act, when things are not under
control or an appropriate response is not being undertaken.
2.18. QUALITY AT THE SOURCE
Quality at the source is a lean manufacturing principle which defines that quality
output is not only measured at the end of the production line but at every step of
the productive process and being the responsibility of each individual who contributes to
the production or on time delivery of a product or service.
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In a practical sense it would involve each operator checking his or her own work
before the part/component or product is sent to the next step in the process. This practice
when first implemented within the workforce will be a challenging change to company
culture but will highlight the relevance of the product's or service's conformance to
customer requirements and standards, thus also imparting the importance of quality
standards and customer satisfaction within the workforce.
Implementing Quality at the source:In order to make the cultural shift within an operation's workforce to embrace
quality at the source the following items should be considered:
-Employee understanding of who the customer is and their requirements
-Internal quality audits
-Employee and team awareness of quality standards and benchmarks
-Employee understanding of the customer's intended use of the product or service
-Multi-skilled workforce which can provide support and help in different process steps
-Required tools and technology to identify quality flaws and rectify them in an efficient
manner
-Proper data collection and tracking of quality faults
-Open communication of standards, performance and processes.
The advantages of quality at the source are many, including: better informed
employees, cultural awareness of the importance of quality to the customer, reduction in
rework expenses, reduction in production production waste, improvement in plant and
process OEE, and most importantly he empowerment of employees in achieving the
desired quality standard required by customers.
2.19. PILLARS OF LEAN MANUFACTURING
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Fig. 2.27. Pillars of Lean
The main pillars of Lean then are Jidoka (Built in Quality) and Just in Time (JIT),
these are supported by the participation of all staff within the company. Every individual is
respected and expected to perform as part of the team to continually improve every aspect
of the business through Kiazen. All of this is focused on satisfying the customers and
making the business a success for everyone.
2.20. JUST IN TIME
Just-In-Time (JIT) is a purchasing and inventory control method in which materials
are obtained just-in-time for production to provide finished goods just-in-time for sale. JIT is
a demand-pull system. Demand for customer output (not plans for using input resources)
triggers production. Production activities are “pulled” not “pushed” into action.
As philosophy, JIT targets inventory as an evil presence that obscures problems
that should be solved, and declares that, by contributing significantly to casts, target
inventories keep a company from being as competitive or profitable as it otherwise might
be.
A just-in-time manufacturing system requires making goods or service only when
the customer, internal or external, requires it. JIT requires better coordination with
suppliers so that materials arrive immediately prior to their use. It reduces or eliminates
inventory and the costs associated with carrying the inventory. It emphasises that workers
immediately correct the system making defective units because they have no inventory.
JIT aims to achieve the following objectives:1. Zero inventory2. Zero breakdowns
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3. 100% on time delivery4. Elimination of Non value added activities5. Zero defects.
JIT applies to raw materials inventory as well as to work-in-process inventory. The
goals are that both raw materials and work in process inventory are held to absolute
minimums. JIT is used to complement other materials planning and control tools, such as
EOQ and safety stock levels. In JIT system, production of an item does not commence
until the organisation receives an order.
When an order is received for a finished product, productions people give orders
for raw materials. As soon as production is complete to fill the order, production ends. In
theory, in JIT, there is no need for inventories because no production takes place until the
organisation knows that it will sell them. In practice, however, companies using just-in-time
inventory generally have a backlog of orders or stable demand for their products to assure
continued production.
The fundamental objective of JIT is to produce and deliver what is needed, when it
is needed, at all stages of the production process-just-in-time to be fabricated, sub-
assembled, assembled, and dispatched to the customer. Although in practice there are no
such perfect plants, JIT is an ideal and therefore a worthy goal.
The benefits are low inventory, high manufacturing cycle rates, high output per
employee, minimum floor space requirements, minimum indirect labour, and perfect in-
process control. An associated requirement of a successful JIT operation is the pursuit of
perfect quality in order to reduce, to an absolute minimum, delays caused by defective
product units.
2.21. JIDOKAJidoka is about built in quality and encompasses ideas such
as Autonomation which is giving machines the “human touch” so that they can stop when
things are incorrect, also Poka Yoke or mistake proofing to prevent defects being
produced, accepted or passed on.
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It also encompasses the philosophy of stopping the production line when defects
are discovered, jidoka provides the framework to drive the non-acceptance of problems
and drives continual improvement.
Jidoka is about quality at source, or built in quality; no company can survive
without excellent quality of product and service and jidoka is the route through which this is
achieved.
Lean relies on Jidoka principles across the various tools and gets us to use visual
management techniques to highlight whenever an abnormality occurs for us to take action.
As team leaders, supervisors and managers we need to keep our eyes open as we walk
through our workplace for these abnormalities and follow through on the Jidoka principles;
1. Discover an abnormality
2. STOP
3. Fix the immediate problem
4. Investigate and correct root cause
This principle is not just confined to use within machines through autonomation ; jidoka
is visible in almost every aspect of lean manufacturing when you start to examine it. It is
about building Quality into a process rather than inspecting for it at the end of the process,
inspection still has a place even in Toyota, and despite what people think can still be a
powerful way of preventing defects reaching the customer.
2.22. 5-S
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Fig. 2.28. 5-S
5S is the name of a workplace organization method that uses a list of
five Japanese words: seiri, seiton, seiso, seiketsu, and shitsuke. Transliterated into Roman
Script, they all start with the letter "S". The list describes how to organize a work space for
efficiency and effectiveness by identifying and storing the items used, maintaining the area
and items, and sustaining the new order. The decision-making process usually comes from
a dialogue about standardization, which builds understanding among employees of how
they should do the work. In some quarters, 5S has become 6S, the sixth element being
safety.
1st S - Sort (Seiri)
Make work easier by eliminating obstacles.
Reduce chances of being disturbed with unnecessary items.
Prevent accumulation of unnecessary items.
Evaluate necessary items with regard to cost or other factors.
Remove all parts or tools that are not in use.
Segregate unwanted material from the workplace.
Define Red-Tag area to place unnecessary items that cannot immediately be disposed
of. Dispose of these items when possible.
Need fully skilled supervisor for checking on a regular basis.
Waste removal.
Make clear all working floor except using material.
2nd S - Set In Order (Seiton)
Arrange all necessary items so that they can be easily selected for use.
Prevent loss and waste of time by arranging work station in such a way that all tooling /
equipment is in close proximity.
Make it easy to find and pick up necessary items.
Ensure first-in-first-out FIFO basis.
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Make workflow smooth and easy.
All of the above work should be done on a regular basis.
Maintain safety.
Place components according to their uses, with the frequently used components being
nearest to the work place.
3rd S - Shine (Seiso)
Clean your workplace on daily basis completely or set cleaning frequency
Use cleaning as inspection.
Prevent machinery and equipment deterioration.
Keep workplace safe and easy to work.
Keep workplace clean and pleasing to work in.
When in place, anyone not familiar to the environment must be able to detect any
problems within 50 feet
4th S - Standardize (Seiketsu)
Standardize the best practices in the work area.
Maintain high standards in workplace organization at all times.
Everything in its right place.
Every process has a standard.
5th S - Sustain (Shitsuke)
Not harmful to anyone.
Also translates as "do without being told".
Perform regular audits.
Training and discipline.
Training is goal-oriented process. Its resulting feedback is necessary monthly.
Self discipline
To maintain proper order
2.23. TPM
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Total Productive Maintenance (TPM) is a system of maintaining and improving
the integrity of production and quality systems through the machines, equipment,
processes, and employees that add business value to an organization.
TPM focuses on keeping all equipment in top working condition to avoid
breakdowns and delays in manufacturing processes.
One of the main objectives of TPM is to increase the productivity of plant and
equipment with a modest investment in maintenance. Total quality management (TQM)
and total productive maintenance (TPM) are considered as the key operational activities of
the quality management system.
In order for TPM to be effective, the full support of the total workforce is required.
This should result in accomplishing the goal of TPM: "Enhance the volume of the
production, employee morale and job satisfaction."
The main objective of TPM is to increase the Overall Equipment Effectiveness of
plant equipment. TPM addresses the causes for accelerated deterioration while creating
the correct environment between operators and equipment to create ownership.
OEE has three factors which are multiplied to give one measure called OEE
Performance x Availability x Quality = OEE
Each factor has two associated losses making 6 in total, these 6 losses are as follows:
Performance = (1) running at reduced speed - (2) Minor Stops
Availability = (3) Breakdowns - (4) Product changeover
Quality = (5) Startup rejects - (6) Running rejects.
The eight pillars of TPM are mostly focused on proactive and preventive techniques
for improving equipment reliability:
1. Autonomous maintenance
2. Planned Maintenance
3. Quality maintenance
4. Kobetsu Kaizen
5. Early Equipment Management
6. Training and Education
7. Safety, Health & Environment
8. Office TPM
With the help of these pillars we can increase productivity.
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Fig. 2.28. Eight pillars of TPM
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TPM Pillars Description Advantages
1
Autonomous
Maintenance
Hands operators of
equipment responsibility to
carry out basic maintenance
of equipment
Operators feel responsible
for their machines,
equipment becomes more
reliable
2Planned
Maintenance
Maintenance scheduled
using the historic failure rate
of equipment
Maintenance can be
scheduled when
production activities are
few
3 Quality
maintenance
Quality ingrained in the
equipment so as to reduce
defects
Defect reduction &
consequent profit
improvement
4Kobetsu Kaizen
Use of cross-functional
teams for improvement
activities
Improves problem solving
capabilities of the workers
5Early Equipment
Maintenance
Design of new equipment
using lesson learnt from
previous TPM activities
New equipment achieves
full potential in a shorter
period of time
6
Training & Education
Bridging of the skills and
knowledge gap through
training of all workers
Employees gain the
necessary skills to enable
them solve problems
within the organization
7Health, Safety &
Environment
Providing of an ideal
working environment devoid
of accidents and injuries
Elimination of harmful
conditions & healthy
workforce
8Office TPM
Spread of the principles to
administrative functions
within an organization
Support functions
understand the benefits of
these improvements
Six Big Losses of Production:
In addition to the losses described in the OEE metric, production units experience
six common losses which reduce the productivity of an organization.
By addressing these losses, a total productive maintenance program results in
increased productivity through reduction of wasteful conditions within processes.
The following table shows the six big losses, their relation to OEE and typical examples in
a production facility:
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Big LossesOEE Loss Classification
Examples Remarks
1
Machine
Breakdowns
Downtime
Loss
Fan belt breakage,
tool failures, motor
breakdown
Must be clearly
defined so as not to
confuse with small
stops
2Setup Loss and
Minor
Adjustments
Downtime
Loss
Product change-
over, staff
shortage,
material shortage
SMED is used for
reducing the effects of
this loss
3
Minor StoppagesSpeed
Loss
Inspection, jams,
adjustments,
blocked sensing
devices,
Very short stops (-
5mins) not requiring
technical intervention
4
Slow RunningSpeed
Loss
Poor settings and
alignment
Factors that prevent
the design
capacity/speed from
been achieved
5
Start-up ErrorsQuality
Lossscrap and rework
Occur before the
process starts in
earnest
6Product Defects
Quality
Lossscrap and rework
Occur during the
running of the process
TPM Implementation Steps:
1. PilotingThe first step in implementing the program should start with the identification of a
pilot area. The importance of this approach is that the program will gain more acceptance
and momentum when staff realise the benefits that accrue from its implementation.
2. Restore Equipment Back to Basic ConditionMachines and equipment are returned to their basic condition through a thorough
5S program coupled with autonomous maintenance as discussed above.
3.OEE TrackingOn completion of the preparatory steps of 5S and autonomous maintenance, the
next logical step is to track the Overall Equipment Effectiveness. This data collection is
important so as to identify the biggest causes of downtime on critical machines.
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4. Reduce Major LossesReducing the major losses based on the data involves:
Selecting a cross-functional team from a wide section of the workforce and should
comprise of all cadres including operators, technical staff as well supervisors
Data analysis of the major losses as collected from the OEE data.
Root cause analysis of why the losses occurred in the first place.
Implementation of suggested solutions within a specified time frame
Verify effectiveness of the implemented solutions through audits
5. Planned MaintenancePlanned maintenance is a very advanced part of the TPM implementation journey
because it happens only after other components have matured enough to be left on their
own and any benefits accruing from the programs have been exhausted.
2.24. SIX SIGMA
Six Sigma (6σ) is a set of techniques and tools for process improvement. It seeks
to improve the quality of the output of a process by identifying and removing the causes of
defects and minimizing variability in manufacturing and business processes. It uses a set
of quality management methods, mainly empirical, statistical methods, and creates a
special infrastructure of people within the organization who are experts in these methods.
Each Six Sigma project carried out within an organization follows a defined
sequence of steps and has specific value targets, for example: reduce process cycle time,
reduce pollution, reduce costs, increase customer satisfaction, and increase profits.
The maturity of a manufacturing process can be described by a sigma rating
indicating its yield or the percentage of defect-free products it creates. A six sigma process
is one in which 99.99966% of all opportunities to produce some feature of a part are
statistically expected to be free of defects (3.4 defective features per million opportunities).
Motorola set a goal of "six sigma" for all of its manufacturing operations, and this goal
became a by-word for the management and engineering practices used to achieve it.
Six Sigma projects follow two project methodologies inspired by Deming's Plan-Do-
Check-Act Cycle. T
These methodologies, composed of five phases each, bear the acronyms DMAIC
and DMADV.
DMAIC is used for projects aimed at improving an existing business process.
DMADV is used for projects aimed at creating new product or process designs.
The DMAIC project methodology has five phases:
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Fig. 2.29. DMAIC
Define the system, the voice of the customer and their requirements, and the project
goals, specifically.
Measure key aspects of the current process and collect relevant data; calculate the
'as-is' Process Capability.
Analyze the data to investigate and verify cause-and-effect relationships. Determine
what the relationships are, and attempt to ensure that all factors have been
considered. Seek out root cause of the defect under investigation.
Improve or optimize the current process based upon data analysis using techniques
such as design of experiments, poka yoke or mistake proofing, and standard work to
create a new, future state process. Set up pilot runs to establish process capability.
Control the future state process to ensure that any deviations from the target are
corrected before they result in defects. Implement control systems such as statistical
process control, production boards, visual workplaces, and continuously monitor the
process. This process is repeated until the desired quality level is obtained.
The DMADV project methodology, known as DFSS ("Design For Six Sigma"), features five phases:
Fig. 2.30. DMAIC
Define design goals that are consistent with customer demands and the enterprise
strategy.
Measure and identify CTQs (characteristics that are Critical To Quality), measure
product capabilities, production process capability, and measure risks.
Analyze to develop and design alternatives
Design an improved alternative, best suited per analysis in the previous step
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Verify the design, set up pilot runs, implement the production process and hand it over
to the process owner(s).
2.25. DFMA
DFMA stands for Design for Manufacture and Assembly. DFMA is the combination
of two methodologies; Design for Manufacture, which means the design for ease of
manufacture of the parts that will form a product, and Design for Assembly, which means
the design of the product for ease of assembly.
Fig.2.31.DFMA
DFM is the method of design for ease of manufacturing of the collection of parts
that will form the product after assembly.
DFA is the method of design of the product for ease of assembly. DFA is a tool
used to assist the design teams in the design of products that will transition to productions
at a minimum cost, focusing on the number of parts, handling and ease of assembly.
PRINCIPLES IN DESIGN FOR MANUFACTURING AND ASSEMBLY:1. Minimize number of components. Assembly costs are reduced. The final product is
more reliable because there are fewer connections. Disassembly for maintenance and field
service is easier. Reduced part count usually means automation is easier to implement.
Work-in-process is reduced, and there are fewer inventory control problems. Fewer parts
need to be purchased, which reduces ordering costs.
2. Use standard commercially available components. Design time and effort are
reduced. Design of custom-engineered components is avoided. There are fewer part
numbers. Inventory control is facilitated. Quantity discounts may be possible.
3. Use common parts across product lines. There is an opportunity to apply group
technology. Implementation of manufacturing cells may be possible. Quantity discounts
may be possible.
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4. Design for ease of part fabrication. Net shape and near net shape processes may be
feasible. Part geometry is simplified, and unnecessary features are avoided. Unnecessary
surface finish requirements should be avoided; otherwise, additional processing may be
needed.
5. Design parts with tolerances that are within process capability. Tolerances tighter
than the process capability should be avoided; otherwise, additional processing will be
required. Bilateral tolerances should be specified.
6. Design the product to be foolproof during assembly. Assembly should be
unambiguous. Components should be designed so they can be assembled only one way.
Special geometric features must sometimes be added to components to achieve foolproof
assembly.
7. Minimize use of flexible components. Flexible components include parts made of
rubber, belts, gaskets, cables, etc. Flexible components are generally more difficult to
handle and assemble.
8. Design for ease of assembly. Part features such as chamfers and tapers should be
designed on mating parts. Design the assembly using base parts to which other
components are added. The assembly should be designed so that components are added
from one direction, usually vertically. Threaded fasteners (screws, bolts, nuts) should be
avoided where possible, especially when automated assembly is used; instead, fast
assembly techniques such as snap fits and adhesive bonding should be employed. The
number of distinct fasteners should be minimized.
9. Use modular design. Each subassembly should consist of five to fifteen parts.
Maintenance and repair are facilitated. Automated and manual assembly are implemented
more readily. Inventory requirements are reduced. Final assembly time is minimized.
10. Shape parts and products for ease of packaging. The product should be designed
so that standard packaging cartons can be used, which are compatible with automated
packaging equipment. Shipment to customer is facilitated.
11. Eliminate or reduce adjustment required. Adjustments are time-consuming in
assembly. Designing adjustments into the product means more opportunities for out-of-
adjustment conditions to arise.
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2.26. KAIZEN
Fig.2.32. Kaizen
The Japanese word kaizen simply means "change for better", with no inherent
meaning of either "continuous" or "philosophy" in Japanese dictionaries or in everyday
use. The word refers to any improvement, one-time or continuous, large or small, in the
same sense as the English word "improvement". Two kaizen approaches have been
distinguished:
flow kaizen;
process kaizen.
The former is oriented towards the flow of materials and information, and is often
identified with the reorganization of an entire production area, even a company. The latter
means the improvement of individual work stands. Therefore, improving the way
production workers do their job is a part of a process kaizen. The use of the kaizen model
for continuous improvement demands that both flow and process kaizens are used,
although process kaizens are used more often to focus workers on continuous small
improvements.
In this model, operators mostly look for small ideas which, if possible, can be
implemented on the same day. Kaizen is a daily process, the purpose of which goes
beyond simple productivity improvement. It is also a process that, when done correctly,
humanizes the workplace, eliminates overly hard work (muri), and teaches people how to
perform experiments on their work using the scientific method and how to learn to spot and
eliminate waste in business processes.
People at all levels of an organization participate in kaizen, from the CEO down to
janitorial staff, as well as external stakeholders when applicable. Kaizen is most commonly
associated with manufacturing operations, as at Toyota, but has also been used in non-
manufacturing environments.
In modern usage, it is designed to address a particular issue over the course of a
week and is referred to as a "kaizen blitz" or "kaizen event". These are limited in scope,
and issues that arise from them are typically used in later blitzes. A person who makes a
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large contribution in the successful implementation of kaizen during kaizen events is
awarded the title of "Zenkai".
The Toyota Production System is known for kaizen, where all line personnel are
expected to stop their moving production line in case of any abnormality and, along with
their supervisor, suggest an improvement to resolve the abnormality which may initiate a
kaizen.
Fig.2.33. PDCA cycle
The cycle of kaizen activity can be defined as: "Plan → Do → Check → Act". This
is also known as, Deming cycle, or PDCA.Another technique used in conjunction with
PDCA is the 5 Whys, which is a form of root cause analysis in which the user asks a series
of five "why" questions about a failure that has occurred, basing each subsequent question
on the answer to the previous. There are normally a series of causes stemming from one
root cause, and they can be visualized using fishbone diagrams or tables. The Five Whys
can be used as a foundational tool in personal improvement, [18] or as a means to create
wealth.
The basic concept is to identify and quickly remove waste. Another approach is that
of the kaizen burst, a specific kaizen activity on a particular process in the value
stream. Kaizen facilitators generally go through training and certification before attempting
a Kaizen project.
Kaizen is continuous improvement that is based on certain guiding principles: Good processes bring good results
Go see for yourself to grasp the current situation
Speak with data, manage by facts
Take action to contain and correct root causes of problems
Work as a team
Kaizen is everybody’s business
And much more!
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140ME9122 Lean Manufacturing – Unit II
One of the most notable features of kaizen is that big results come from many
small changes accumulated over time. However this has been misunderstood to mean that
kaizen equals small changes. In fact, kaizen means everyone involved in making
improvements. While the majority of changes may be small, the greatest impact may be
kaizens that are led by senior management as transformational projects, or by cross-
functional teams as kaizen events.
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Additional Topics:1. Shadow boards
2. Clock chart
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140ME9122 Lean Manufacturing – Unit II
Review QuestionsPart –A ( 1 Mark)1. Ishikawa Diagrams is also called as ______________________
a. Fishbone Diagrams, b. Process mapping, c. Pareto Diagram, d. Spaghetti diagram
2. A ________________is a visual representation using a continuous flow line tracing the
path of an item through a process.
a. Fishbone Diagrams, b. Process mapping, c. Pareto Diagram, d. Spaghetti diagram
3. ____________ is a technique that developed out of the Toyota Production system
through Jidoka and Autonomation.
a. Kaizen, b. 5S, c.Poka Yoke, d.TPM
4. Kanban is one method to achieve _________ .
a. JIT, b. TPM, c. TQM, d. All the above.
5. The first step of ________ is separation internal from external setup operations
a. TPM, c. Kaizen, c. SMED, d. Anodon
6. Genchi gembutsu means __________
a. Go and see for yourself, b. Safety workplace, c. Continuous improvement,
d. Elimination of waste
7. _________________ is a visual control.
a. Foot printing, b. Stripping, c. shadowing , d. All the above
8. To overcome the inefficiencies of inspection through the use of automatic devices called
________________ .
a. Poka Yoke, b. SMED, c. Anodon, d. DFMA
9. Just-In-Time (JIT) is ____________ system.
a. Push, b. Pull, c. Linear, d. Quick
10. ________ is the sixth ‘S’ of 5-S.
a. Standardize, b. Sustain, c. Safety, d. Security
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140ME9122 Lean Manufacturing – Unit II
11. Everything in its right place is called as _________
a. Sort, b. Simplify, c. Standardize, d. Sustain
12. ________ event is awarded the title of "Zenkai".
a. Lean b. Six sigma c. TPM, d. Kaizen
13. ____________ is used for projects aimed at improving an existing business process.
a. DMADV, b. DMAIC, c. Kaizen, d. TPM
14. ______ is the base of TPM.
a. TQM, b.5S, c. Kaizen, d.Lean
15. Pareto analysis based on ______ rule.
16. _______ work area layout that enables workers to easily move from one process to
another in close proximity and pass parts between workers with little effort.
17.___________ is a step-by-step approach for identifying all possible failures in a design,
a manufacturing or assembly process.
18. ___________ gives the worker the ability, and moreover the empowerment, to stop
production when a defect is found, and immediately call for assistance.
19. Tact time is equal to _______________
20. Overall Equipment Effectiveness is the measurement of _________________
Answers:
1) a. Fishbone Diagrams , 2) d.Spaghetti diagram, 3) c.Poka Yoke, 4) a. JIT,
5) c. SMED, 6) a. Go and see for yourself, 7) d. All the above, 8) a. Poka Yoke, 9)
b. Pull, 10) c. Safety, 11) c. Standardize, 12) d. Kaizen, 13) b. DMAIC, 14) b.5S, 15)
80/20, 16) U , 17) FMEA, 18) Andon, 19) Available work-time / Customer demand, 20)
TPM.
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140ME9122 Lean Manufacturing – Unit II
Part – B (2 Marks)1. List out the various application of Cause and Effect diagram. Discover the root cause of a problem.
Uncover bottlenecks in processes.
Identify where and why a process isn't working.
2. What are the major categories of causes in Cause and Effect diagram? People
Methods
Machines
Materials
Measurements
Environment
3. What is ‘80/20’ rule in Pareto analysis ?Under the assumption of Pareto analysis, in all situations, 20% of causes
determine 80% of problems.
4. When FMEA to be applied in process? When a process, product or service is being designed or redesigned, after quality
function deployment.
When an existing process, product or service is being applied in a new way.
Before developing control plans for a new or modified process.
When improvement goals are planned for an existing process, product or service.
When analyzing failures of an existing process, product or service.
Periodically throughout the life of the process, product or service
5. Define Work cell.A work cell is an arrangement of resources in a manufacturing environment to
improve the quality, speed and cost of the process.
6. What are rules established for reordering tools?
For perishable tools - reorder when the total quantity of tools in the crib inventory is
below the defined minimum quantity.
For durable tools - reorder when the total on-hand quantity of tools is below the
defined minimum quantity.
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140ME9122 Lean Manufacturing – Unit II
7. List out the purpose of process mapping. The purpose of process mapping is for organizations and businesses to improve
efficiency.
Process maps provide insight into a process.
Process mapping will identify bottlenecks, repetition and delays.
The better understanding of a process.
8. Write down any four process mapping techniques. Activity Process Map
Detailed Process Map
Document Map
High-Level Process Map
Rendered Process Map
Cross-functional Map
Value Stream Map
9. Where Spaghetti diagrams are used?Spaghetti diagrams are used to track Product Flow, Paper Flow and People Flow.
10. What is Poka Yoke?Poka Yoke is a simple technique that developed to do three things:
Not accept a defect for the process
Not Create a Defect
Not Allow a Defect to be passed to the next process
11. Compare P & T Kanban.
Production (P) Kanban Transportation (T) Kanban
A P-kanban, when received, authorizes the
workstation to produce a fixed amount of
products.
A T-kanban authorizes the transportation of
the full container to the downstream
workstation
The P-kanban is carried on the containers
that are associated with it.
The T-kanban is also carried on the
containers that are associated with the
transportation to move through the loop
again.
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140ME9122 Lean Manufacturing – Unit II
12.List out various Andon systems.Andon systems can include text, graphics, or audio elements. Audio alerts may be done
with coded tones, music with different tunes corresponding to the various alerts, or pre-
recorded verbal messages.
13. Write down the four conceptual stages of SMED.A) ensure that external setup actions are performed while the machine is still running,
B) separate external and internal setup actions, ensure that the parts all function and
implement efficient ways of transporting the die and other parts,
C) convert internal setup actions to external,
D) improve all setup actions.
14. Compare one piece flow and Queue Batch flow.
15. What is a Visual Work place?A Visual workplace can be Self- ordering, Self- explaning, self-regulating and self-
improving.
16. Write down the objectives of JIT.
1. Zero inventory2. Zero breakdowns3. 100% on time delivery
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140ME9122 Lean Manufacturing – Unit II
4. Elimination of Non value added activities5. Zero defects.
17. Differentiate JIT and Traditional process.
18. What are the four principles of Jidoka?1.Discover an abnormality
2.STOP
3.Fix the immediate problem
4.Investigate and correct root cause
19. List out the 5-S of workplace.1. Sort ,
2. Simplify,
3. Shine,
4. Standardize and
5. Sustain.
20. What are the six bid losses identified in TPM.1 Machine Breakdowns
2 Setup Loss and Minor Adjustments
3 Minor Stoppages
4 Slow Running
5 Start-up Errors
6 Product Defects
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140ME9122 Lean Manufacturing – Unit II
21. List out the steps involved in TPM Implementation.1. Piloting
2. Restore Equipment Back to Basic Condition
3. OEE Tracking
4. Reduce Major Losses
5. Planned Maintenance
22. What is DFMA?DFMA stands for Design for Manufacture and Assembly. DFMA is the combination
of two methodologies; Design for Manufacture, which means the design for ease of
manufacture of the parts that will form a product, and Design for Assembly, which means
the design of the product for ease of assembly.
23. Write down the basic Kaizen guiding principles. Good processes bring good results
Go see for yourself to grasp the current situation
Speak with data, manage by facts
Take action to contain and correct root causes of problems
Work as a team
Part – C:1. Illustrate the procedure to create Cause and Effect diagram.
2. Explain Pareto Diagram with simple sketch.
3. Describe FMEA format and procedure with an example.
4. Illustrate the steps to create a process map with an example.
5. Explain different types of Poka Yoke techniques.
6. Describe ‘Kanban’ system with simple sketch.
7. Explain Seven basic steps to reducing changeover using the SMED.
8. Illustrate pillars of Lean Manufacturing.
9. Explain 5-S principles.10. Describe TPM principles and implementation with suitable example.
11. Explain six sigma methodologies using in Lean manufacturing.
12. Explain the principles in Design for Manufacturing and Assembly.
Assignment – 2 :Prepare a Shadow board using thermocool for keeping the following item: Pen,
Pencil, Eraser, Scale, Bike key, Marker pen and Mobile phone.
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