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Lean, JIT Production Systems
• Philosophy for optimizing the performance of a manufacturing system
• Was designed by Taiichi Ohno
• System is driven by more flexibility and smaller volumes per part
using same equipment
Lean, JIT Production Systems
• Settled on an effective strategy based on:
• Kanban – based pull production
• Elimination of waste as a guiding philosophy
• Faith in the value and importance of quality
• Belief in the value and utilization of human resources
• Emphasis on reducing setup times for machines
• Integration of suppliers and material acquisition into the corporate planning process
• Efficient, cellular layouts with balanced material flow
Improving the Production Environment
• Eliminating waste (TIM WOODS)
• Employee Cross-Training and Job Rotation
• Employee Empowerment and Involvement
• JIT purchasing
• Impact of reducing variability
• Economics of Setup Time Reduction
• Technology of Setup Time Reduction
• T- Transport (Moving People, Products and Information)
• I – Inventory (Storing parts, pieces, documentation ahead of requirements)
• M – Motion (Bending, turning, reaching, lifting)
• W – Waiting (For parts, information, instructions, equipment)
• O – Overproduction (making more than is immediately required)
• O – Overprocessing (tighter tolerances and high grade material use than are necessary)
• D – Defects (Rework, Scrap and incorrect documentation)
• S – Skills (underutilizing capabilities and delegating tasks with inadequate training)
The aim is to reduce the overall
mileage or footprint a product /
service accumulates as it moves
through the organization, resulting
in an increase in the proportion of
the value – added activity.
Transport is the unnecessary movement of a product, raw material, or
documents. Moving items unnecessarily increases the risk of damage or
loss, adds time and adds cost without adding value. Poor layout of the
floor / office / work area, batching and lac of flow all contribute to this
Inventory should be systematically
reduced as holding stock hides
problems in processes; reducing
stock exposes issues and forces
organisations to resolve them.
In a service/administration environment it can be an accumulation of
physical documents or electronic files, over an above what is required
to satisfy the customer’s requirement.
Holding excess stock represents a cost to the company, with no benefit
to the customer. The waste of inventory results from poor design of the
elements of the value stream, resulting in overproduction and
imbalances in work flows.
Waste will be reduced by the
implementation of a workplace
organisation programme to re-
organise the workplace ensuring
processes are located closer to
each other, that material delivery
areas are at the point of use and
tools and equipment are close to
The result of implementing such a
programme will reduce the
distance travelled by the person
saving time and even “wear & tear”
on the employee in the long term.
This waste is similar to the waste of Transport, but refers to the time
wasted by individuals moving around when they don’t need to, to
collect parts or search for something they need to complete the job e.g.
tools or equipment.
The ideal is to produce single piece
at a time also referred to as single
piece flow. This may not be always
practical, but the goal is to reduce
batch size, to reduce changeover
time and waiting for parts between
This equally applies to operations
where the output is not a physical
item. Work should be scheduled in
sufficiently small increments to
allow the unit of work (e.g. a file, a
report) to flow smoothly through
the individual process steps to be
delivered in a timely fashion.
Waiting refers to the time an item spends between process steps, when
no work is being performed and therefore no value added. For
example, in manufacturing environments if batch production is
practiced, individual products will wait between process steps while the
remainder of the batch is processed
The remedy is to work to customer
demand, improve flow through
individual process steps to produce
only what the customer needs
when he needs it. It is also
preferable that the ‘load’ on
production be as consistent as
possible to allow resources to be
better planned thus minimising
This waste is directly related to the waste of Inventory which is as a
result of not responding to customer demand. Continuing to produce
what is not required leads to an accumulation of stock between process
steps and at the end of the process. Overproduction occurs when
production runs ahead of demand; items are produced in greater
volume than required, sooner than required or faster than required.
Overprocessing is eliminated by a
thorough understanding of what
exactly is required to fulfil customer
needs and simplifying &
standardizing the processes to
deliver these expectations.
This waste applies when more work is done than is required to meet
customer expectations, performing wasteful steps that may not be
Defects can be reduced by ensuring that all work
steps are highly specified with no ambiguity. All
the required tools and equipment are present
and in good working order (achieved through a
workplace organisation programme). Instructions
are clear, concise and photographs should be
used as much as possible. Personnel must be
trained in all aspects of the job. The result of
implementing such a programme will reduce the
distance travelled by the person saving time and
even “wear & tear” on the employee in the long
A concept called “Error-Proofing” is employed to
reduce as much as possible the occurrence of
defects. Error-proofing is a structured process
which seeks to prevent errors through robust
product and process design, to eliminate or
immediately detect defects as they occur.
A defect is the result of an error; it is a deviation from the product
specification which leads to customer dissatisfaction. In a service
environment, it could be data input errors, a report incorrectly filled
out, an error in billing etc.
Production defects lead to the cost of reworking. Reworking leads to a
double handling of product which add costs and also exposes the
product to further risk of damage.
their expertise, and challenges
them to question old ways, gather
real-time data and design creative
solutions to resolve issues.
This waste describes the situation where management functions within a
company don’t fully utilize employees’ skillsets, the experience which
people bring to their jobs, or develop over time in the performance of their
jobs. It relates to the concept of “Respect for People”.
The core of the Lean Production System is the relentless elimination of
waste, however the culture of continuous improvement depends on all
team members contributing ideas for possible improvement, also being in a
position to implement and sustain such improvements once introduced.
Value Stream Mapping
• Visual tool used to illustrate how a process flow and information flow, transform a product as it moves
through the value stream.
• It’s purpose is to identify the source of waste and drive action plan to eliminate them.
• VSM shows both the process and information flow, tracking the material’s progress from the raw material
supplier to the end customer.
• In service terms, a VSM typically details the process steps and the flow of a report or file through these
• The timeline at the bottom of the chart compares the time where value is being added with the overall lead
time to provide the product or service.
Value Stream Mapping
There are three Value Stream Map variants:
• The Current State (see overleaf for an example) or the current condition.
• The Ideal State, which represents the long term vision, and
• The Future State which represents an interim step toward the Ideal State, usually involving a series of improvements which
are achieved within an agreed time period, through a defined action plan.
Employee Cross Training
• Enhances worker flexibility and enthusiasm
• Workers trained over time to perform a variety of tasks within their work area
• Rotation possible through cross training
• Prevents boredom and monotony and does job enrichment
• Minimizes fatigue and repetitive stress injuries
• Increases manufacturing flexibility also.
U Shaped Cell
• Results in short walking distances between machines and good visibility
• Production rate of the machine can be adjusted easily
• More appropriate where it is possible to deploy one person for two machines
• Flexible enough to reduce or add workers as the need be
Disadvantages of Cross Training
• Too much cross training is detrimental
• Workers may be tempted to stray from their primary jobs thus affecting productivity
• Can be expensive where bottleneck operations will start building a queue
• Workers can get in each others ways
• Directed towards achieving quality and productivity improvement goals.
• Includes minor investment and procedural changes to support continuous improvement.
• Authority to stop and correct a production system that is not operating properly so as to reduce cost
of making bad products.
• Directed towards reducing the “Hidden factory” which is 10% of the capacity used for correcting a
badly made product.
• Can achieve the JIDOKA at workplace.
The Andon System for JIDOKA
• Provide each line worker with a stop switch to stop the production
• Identify and solve the problem immediately as soon as it appears
instead of the philosophy of “just ship it, we’ll fix it later”
• One light will always be lit so as to display the status of that work
• Directed at reducing customer complaints as the problems are
nipped in the bud.
SOPs as Performance Enhancers
• Help in ensuring consistency in productivity and
• Employee involvement is a must in SOP
development as they can envisage experiential
problems and can help in building procedures more
• Lesser resistance if employee involvement is there.
• Implementation of 5S to systematically organize
workplace leading to reduced customer complaints.
Approaches to Decision
• Sole Sourcing Versus Multiple Sources
• Frequent Delivery of Small Lots versus Quantity
• Flexible Ordering Versus Paperwork
• Vendor owned and Managed Inventories
• Technology providing benefits by creating genetic mutations leading to improvements in process.
• In a thoughtfully designed production system, variability impedes efficiency
• This gives rise to building up of safety stocks as customer delivery is of prime importance.
• The efficiency of the production system can be increased by creating an optimized flow of material
that matches with the availability of storage buffers between workstations.
A Change in the Die Design
• In some operations (for example in stamping,
drilling…), a die is necessary and can be placed
incorrectly. That error can result in product quality
issues and in damage done to the die.
• How to avoid this? By making it impossible to place
the die only in one way. This can be realized in
many ways. An approach is to have guide pins of
different sizes, so that they can only “fit” in one
direction. There are many other approaches.
A Change in Fixture Design
• This is relatively similar to point 1, with a key
difference: the part being worked on can be placed
the wrong way into a fixture, with resulting quality
• The fixture can be modified in order to make it
impossible to place the part incorrectly.
(Sometimes the design of the part itself has to be
changed, for the same effect.)
Sensors That Prevent Processing Under Certain
The most common sensors are listed below:
• Limit switch – convenient when a part is in contact
with a tool/fixture.
• Proximity sensor – a good solution when a part
is/might be at a certain distance.
• Infrared sensor – appropriate for checking
presence from a distance.
A Vision System
• In simple terms, a vision system captures images, analyzes them, and
triggers an action in pre-determined cases. It does not require contact with
• For example, it might detect that a part is poorly positioned, that a
component (or labeling element) is missing, that a step was done before
another, etc. As a response, it might sound an alarm, or it might make it
impossible to proceed (often by stopping a piece of equipment) until a
positive change is made.
• This approach appeared in the 1980s in a simple form and has kept
improving since them.
• With the advances of artificial intelligence / machine learning, vision
systems will get better and better. Remember, a Tesla car can pretty much
self-drive based on cameras alone!
• By any standard, a checklist is one of the weakest mistake proofing
techniques. It does help a lot when no other approach listed above is
possible and when operators are trained and careful – think pilots in a
• The more a checklist’s elements are integrated into the work content,
the better. Think of color codes where a checklist step matches a
certain tool. Or a form to fill out that contains the steps in the right
• Poka yokes are a science but also an art. Think this
way and you will see many opportunities that will
take different shapes depending on the application.
• For example, let’s say some parts move on a
conveyor. A few of them have a defect and are taller.
The “obvious” countermeasure is a sensor that
detects that abnormality. But a better approach is to
place a stick that will block the way to all defective
parts and push them into a red container on the side
of the conveyor. It is faster and cheaper to
implement, it is easier to maintain, and it
immediately acts on its findings!
Design Parts for
• Manufacture with reasonable tolerances
• Use as much Standard tools as possible
• Control Tooling changeovers
• Do Industrial Engineering through man machine
charting of processes
• Improve and redesign processes to standardized and
Divide Setup Activities into
Internal & External Tasks
• Obtaining Tooling, reading blueprints, prepositioning
fixtures for easy roll onto the machine are external
• Move as many activities as possible from Internal to
Design Procedures to Perform
Setup Tasks in Parallel
• By performing internal setup tasks in parallel, total
idle time of the machine for setups is reduced.
Utilize Family Tooling to
Minimize the Need for Setups
• Construction of family fixture
• Setting up of Tool magazines
• Use of modular fixtures
• Use of Standard Clamps
Locally Stored Tools and
• Tools to be stored near
• Develop methods such as
standard height carts or
conveyors for quicker tool
Standard sized Intermediate
• Tooling even if not the same size, may
be expedient to design the tooling with
• Semiconductor industry has adopted
this method of quick changing for
• Foolproof the set up process.
• Self diagnostic machines should be more
• Add Limit switches to aid in alignment
tooling or setting stroke lengths with
Use of Power Clamps
• Use of Hydraulic or Pneumatic
power clamps instead of manual
• Use of items like washers to reduce
the tightening and loosening