Blog 25: 14 Principles of Lean Manufacturing (2)


Lean Manufacturing dates to the 1940’s when Taiichi Ohno developed the Toyota Production System. A system that introduced mass production of cars in Japan like the pattern used by the American industries. The word lean was extracted from the book “The Machine That Changed the World” written by James Womack, Daniel Jones, and Daniel Roos. This book is an extract of Toyota Production System that how can the Toyota production system be used to remove wastages and can be used for the betterment of the industry with using very few resources.

The word Manufacturing is defined as:

“Converting the shape, form, size, looks, by using different value-adding processes on it”

Whereas Lean is defined as:

“Thin, having no fat”

So, combined Lean manufacturing is defined as:

“A set of tool or methodologies that aim for continuous elimination of all waste in production               process and creating an optimum solution”

Lean tools and Techniques:

Following are the lean building blocks or lean tools that are used in the implementation of the lean process in a company.

  • 5S or Visual Control
  • Kaizen
  • Kanban
  • Value stream mapping
  • Push vs Pull
  • SMED (single Minute Exchange of Dies)
  • Root cause analysis
  • Quality and Standardization
  • Total Productive Management
  • Takt Time
  • Just in time
  • Overall Equipment Effectiveness
  • PDCA (plan, do, check, act)

Value Stream Mapping (VSM)

A value stream map is a management tool used to analyze the current state and by improving or changing predict the future state. Value stream mapping is a pencil tool that is used to understand the process or the flow of material. Value stream mapping is not only useful for product activity but the information system also supports the basic process.

Why do we use VSM?

We use value stream map because:

  • Predominantly used to minimize 7 deadly wastages, by identifying and then targeting the sources of waste in the entire production stream rather than just the work unit.
  • Unlike process maps that are limited to mapping the sequence of tasks that are performed to complete a procedure or process, value stream mapping helps to analyze and understand the flow of materials and the information needed to process them – through graphical illustration.
  • Since the value stream mapping integrates information and material flow, the sequence of tasks including cycle time and lag between tasks; it can highlight the inefficiencies, problems, and losses within complex systems
  • It provides a common language for talking about manufacturing processes.
  • It shows the linkage between information flow and material flow. No other does this.
  • It behaves as the blueprint for a lean implementation plan.

How to create VSM

Value stream mapping is best created by hand using pencil on a paper. It is better to involve the whole team to create the VSM rather than have an expert. Steps of making a VSM are as follows

Select the Product Family

Firstly, decide what we must wish to map and then would go to the highest value it is not necessary to analyze all products using Pareto analysis to decide which product to analyze. This analysis will give a clear view of all the problems and the problem that is occurring the most. So based on this we can decide the priority list as to which product is needed to be treated first.


Before making the value stream map one should have sound knowledge about the value stream symbol that will be used during the process.

Bound the Process

We need to decide the limits of our map first. VSM is conducted from supplier through customer and these should be the first boxes placed on your VSM to bound the process.

Make Current Value Stream Map

Using the limits and the tools design the current value stream map with all the required data. This can be done by

  • Always collect current-state information while walking along the actual pathways of material and information flow
  • Begin with a quick walk along the entire door-to-door value stream
  • Begin at the shipping end and work upstream
  • Use a stopwatch and note each individual time instead of relying on standard or filed times
  • Map the whole value stream yourself (or individually)

What can be done to improve the current state map?

After Making the current value stream mapping then the whole process and picture become clear in front of us what and where the losses are. Then we should reduce these losses or wastages by using different processes

Drawing the Future State map

After reducing the losses then we should make the future value stream map using the new data to see the difference between the actual value and predicted value and to find out the total change in each process

Add information flow to tour VSM

We need to add how the customer orders products and how we convert that back to the supplier. We also add how we communicate the requirement to our process.

Push vs Pull

Traditionally production processes are scheduled, raw materials ordered and then manufactured to create stock based on a forecast of what the customer is expected to order. This is push production and is driven very much by the materials being fed into the start of the process and all processes being controlled through a schedule or MRP. This typically produces products in large quantities or batches and ties up a huge amount of your capital in stock and Work in Progress (WIP).

Pull production however works in reverse, when a customer takes a product from the end of your production process a signal is then sent back down the line to trigger the production of the next part. Just as a supermarket will fill the empty shelf each preceding process in the flow will.


Jidoka is the often-forgotten pillar of the Toyota Production System and lean manufacturing yet it is one of the most important principles of lean that can help you achieve true excellence. Jidoka is about quality at source or built-in quality; no company can survive without the excellent quality of products and service and jidoka is the route through which this is achieved.

Jidoka principle:

The principle of Jidoka can be broken down into a few simple steps;

  • Discover an abnormality
  • STOP
  • Fix the immediate problem
  • Investigate and correct the root cause

Jidoka and lean:

The first step of Jidoka is that of detecting an abnormality, so for automation, the machine uses simple sensors to detect a problem and then stops and highlights the problems for the operator. For line stop, the operator detects an abnormality and stops the line, and highlights the problem for all to see on an Andon board.

Other Lean tools use various aspects of visual management to highlight abnormalities, consider 5S, we identify the locations for tools, components, and work in progress, if we see things that are not in their allocated place we have seen an abnormality and should act. Why do we have missing tools? Why are additional stocks being stored where they should not be?

Other tools such as Kanban will also quickly highlight problems, why have these products been moved without Kanban authority?

Look at TPM (Total Productive Maintenance), we replace machine covers with transparent covers that let us see when we have problems more clearly, we use Kamishabi boards to schedule maintenance and other tasks, if cards are not turned we can see at a glance that we have problems.

Root Cause Analysis:

Root cause analysis is the most useful technique that helps people to find out the answer to the question of why the problem occurred in the first place. It helps to identify the origin of the problem by using a specific set of steps:

  • Determine what happened
  • Determine why it happened
  • Figure out what to do to reduce

The root cause analysis process

Root cause analysis gives five steps to solve the problem:

  • Define the problem
  • Collect Data
  • Identify possible causal factors
  • Identify the root cause
  • Recommend and implement solutions


Find the barriers and the causes of the problem so that found a solution that is permanent it also develops a logical approach to solve a problem by using the given data. Establish step by step process so the result of each process can be conforming.


Single Minute Die Exchange (SMED) is a process of reducing the equipment changeover time. The goal is to reduce the change over time from hours to minutes or maybe less. Not all the time is possible, but it can be reduced to the maximum possibility. One possibility of doing this is by moving the internal process to an external process. Internal processes are the process that is done by turning off the machine but the external process can be done while running the machine.


Following are the benefits of SMED.

  • Reduce production time
  • Increase machine work rates
  • Elimination of setup errors
  • Lower expenses of setup
  • Increase safety from similar steps
  • Saves time and manpower
  • Smooth start-ups
  • Lower inventory level


POKE YOKA is a Japanese word that means “Mistake Proofing”. POKE YOKA is any mechanism in lean manufacturing that helps a worker reduce errors during work.


Objectives of POKE YOKA are

  • To prevent an error that leads to defects
  • To detect defects
  • To reduce the number of defects


Following are the benefits of POKE YOKA

  • Less time spent on training workers
  • Elimination of many methods of quality control
  • Elimination of Muda of over-processing
  • Reduce the number of rejects
  • Immediate action when a problem occurs

Quality and Standardization

Standardization is one of the most important building blocks of lean manufacturing. The basic purpose of Lean manufacturing is to increase the quality of products, processes, and other parts and to make them standardized. Standardization allows the process to be decomposed and optimized into simple easy-to-follow steps. Standardized practice allows the workers to perform similar steps every time during the process.

Benefits of standardization:

The following are the benefits of standardization:

  • Reduce wastage of time looking for tools, documents, etc.
  • Improve quality
  • Reduce reworks hence saving the production time
  • Better comprehensive training procedures

Total Productive Maintenance and Total Quality Maintenance:

TPM and TQM are important tools of Lean Manufacturing. The objective of TPM is to increase the productivity of factories and equipment with a modest investment in maintenance. While TQM efforts typically draw heavily on the previously developed tools and techniques of Quality control.

Objectives of TPM:

Following are the objectives of TPM.

  • Autonomous maintenance
  • Focused improvement
  • Planned maintained
  • Quality management
  • Education and training
  • Reduce cost
  • Good send to customer must be non-detective

Objective of TQM:

  • Decrease mistakes in overall process                                                            
  • Early mistake recognition
  • Avoidance of wastages
  • Reduction of the lead time
  • Increase the profitability and flexibility
  • Mistake prevention

Advantages of TQM and TPM:

Following are the advantages and disadvantages of TPM and TQM.

  • Improvement in product quality        
  • Improvement in product design
  • Improvement in production flow
  • Improvement in Product service
  • Reduce maintenance cost
  • Rectify customer complaints
  • Reduce accidents
  • Reduce manufacturing cost

Takt time

Takt time is a German word “TAKZIET” which means music or rhythm of the music. Takt time is defined as

“The maximum acceptable time to meet the customer’s demand”


“The speed in which the product is needed to be created in order to satisfy the need of customer”

Formula to calculate takt time= (Net time available for production)/ (Customer daily demand)

Takt time is one of the most important principles of lean. Takt time of every process of every product should be calculated to get a smooth production.

Benefits of takt time:

Following are the benefits of takt time.

  • Helps in the monitoring of production
  • Helps to reach production goals
  • Helps to give a smooth production flow
  • Reduce overproduction
  • Few errors
  • Better planning

Just in time (JIT):

Just in time is an inventory management tool used by companies to increase efficiency and decrease waste by receiving goods only when they are required hence saving the inventory cost. It is a good technique to be used only when the company’s future forecast is accurate.

Benefits of JIT:

The benefits of JIT are as follows:

  • Reduce inventory cost
  • Labor cost reduction
  • Space reduction
  • Production increase
  • Quality improved

Benefits of Lean Manufacturing:

Following are the benefits of lean manufacturing :

Elimination of wastages:

7 wastages of Muda, Muri and Muda can be completely or reduced to maximum by the implementation of Lean

Quality improvement:

A lot of activities in lean are dedicated for improving the quality of processes, products, workers, and industry. If a quality issue arises lean has problem-solving techniques like root cause analysis to find out the root cause of that problem and then use mistake proofing so that, that problem never occurs again.

Improved Visual Management:

Another benefit of lean is inspection at sight. If lean is applied properly then in term of any wastage or less, you will only require visual aid.

Increase Efficiency:

Line balancing will insure that each person on the line is working at their optimal efficiency and standardization will help to ensure that correct methods are being followed while working.

MAN-power reduction:

One of the main benefits of lean manufacturing is the reduction of non-value workers. When standardization is under implementation then it reduces excess workers. But this does not mean sending these workers to the unemployment list, rather they can be used in other kaizen activities.

Easier to manage:

When the workers are properly trained, and follow the standard process then they know what to do, when to do and how to do. This makes management much easier.

Total company involvement:

Since lean is a management technique that’s why the whole company is involved in applying lean not just any specific area or department. This also create a sense that the whole company is a team and not divided into groups.

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