Wednesday, April 23, 2014

Four Principles of Lean - YouTube Video

The Video gives the four principles as Pull, One piece flow, Tact and Zero Defects.

It can also be said as Produce to order, Small batches as required to deliver, Produce only what is needed and ensure zero defects.

How do you do it? That is where manufacturing or production systems design and industrial engineering come into picture.


Saturday, April 19, 2014

A Study of the Toyota Production System from an Industrial Engineering Viewpoint - Shigeo Shingo - Google Book

The first and only book in English on JIT, written from the industrial engineer's viewpoint. When Omark Industries bought 500 copies and studied it companywide, Omark became the American pioneer in JIT.
Here is Dr. Shingo's classic industrial engineering rationale for the priority of process-based over operational improvements in manufacturing. He explains the basic mechanisms of the Toyota production system, examines production as a functional network of processes and operations, and then discusses the mechanism necessary to make JIT possible in any manufacturing plant.

Provides original source material on Just-ln-Time
Demonstrates new ways to think about profit, inventory, waste, and productivity
Explains the principles of leveling, standard work procedures, multi-machine handling, supplier relations, and much more
If you are a serious student of industrial engineering, you will benefit greatly from reading this primary resource on the powerful fundamentals of JIT.

A summary

Today, I acquired a copy of the book. I shall write a summary shortly.
My Summary
Industrial Engineering in Toyota Production System - Lean Production

Method Study: Methods Efficiency Engineering - Operation Analysis Approach - Knol Book

H.B. Maynard discussed in detail the method study procedure in his book "Operation Analysis" published in 1938. Method study is engineering branch specific. Shigeo Shingo, the Japanese industrial engineer, clearly stated that value engineering or product design efficiency engineering is to be attempted first by industrial engineers. Next comes methods efficiency engineering. Hence engineers of a particular branch are only equipped to analyze the product designs and process designs of that branch from efficiency point of view.

Methods efficiency engineering is divided first into process analysis and operation analysis. In operation analysis, the tolerance specified, material given as input, material handling, equipment, setup, tools, working conditions and operator methods are analysed. Operator method analysis is an altogether independent study known as motion study. Similarly, after method study, to determine standard times time study or other work measurement techniques are used.

1. The Function of Methods Efficiency Engineering

2. Approach to Operation Analysis as a Step in Methods Efficiency Engineering

3. Scope and Limitations of Methods Efficiency Engineering

    Operation Analysis Sheet

    Using the Operation Analysis Sheet

    Analysis of Purpose of Operation

    Analysis of All Operations of a Process as a Step of Each Operation Analysis

    Analysis of Tolerances and Inspection Standards

    Analysis of Material in Operation Analysis

    Tool Related Operation Analysis

    Material Handling Analysis in Operations

    Operation Analysis of Setups

    Operation Analysis - Man and Machine Activity Charts

    Operation Analysis - Plant Layout Analysis

    Operation Analysis - Analysis of Working Conditions and Method

    Operation Analysis - Common Possibilities for Operation Improvement

    Operation Analysis - Check List

Method Study

Principles of Methods Efficiency Engineering

Method Study - Information Collection and Recording - Chapter Contents

Process Analysis - Questions/Check List

Installing Proposed Methods

Process and Operation Improvement is presented in totally different light by Shigeo Shingo in his description of Toyota Production System
Read the full summary of the book in

Standard Operation and Standard Operation Sheets in Toyota Production System

Industrial Engineers, F.W. Taylor, Frank Gilbreth, Harrington Emerson and subsequently H.B. Maynard emphasized the need to employ standard operating procedures in Production and Distribution systems. In Toyota Motors, Taiichi Ohno implemented standard operations with the additional responsibility given to supervisors to ensure that there is improvement in standard operations periodically. The idea that operators and supervisors have to be involved more in operation improvement activities was advocated by Alan Mogensen, an industrial engineer and he named it work simplification. During second world war, American agencies created a training within industry system that emphasized improvement activities to be undertaken by supervisors. Japanese managers and engineers have absorbed all these ideas and Taiichi Ohno and other managers in Toyota Motors came out with world class implementation of IE principles and techniques.

We understand about IE in Japan through the books of Shigeo Shingo and Taiichi Ohno.

Standard Operation and Standard Operation Sheets

Taiichi Ohno wrote:

Standard work sheets and the information contained in them are important elements of the Toyota production system. Standard worksheet must be written in a manner that workers understand it.

In Toyota, standard work sheet is the basis for examining the resources used by an operation and eliminating waste (excess usage of resources), for improving machining processes and tools, installing autonomous systems, analyzing the need for transportation and methods of transportation, and for optimizing the work-in-progress at various steps in the process or operation. Standard work sheet will be updated by steps taken to prevent the recurrence of defects, operational mistakes, accidents and all ideas suggested by operators. Standard work sheet provides the basis for current execution and also for process and operation improvement.

The standard work sheet provides for effective and efficient combination of materials, workers and machines. This combination is termed as work combination in Toyota.

Standard worksheet contains three elements.
1. Work sequence
2. Cycle time
3. Standard inventory

The term work sequence in an operation refers to the various tasks carried out in an operation. It includes the worker picking the item, transporting it to the machine if required, mounting it on the machine, doing the operation, removing it from the machine etc. The job of supervisor, section chief or group foreman is to train workers. When the standard work sheet or work sequence is very clear, it should take only three days to train a new worker (say trained in general machining work) and workers quickly learn to avoid rework involved in producing defective parts.

Cycle time is the time allowed to make one piece or unit. It is actually standard time in the usual terminology. When there is difference between the actual time taken and the standard time, in most cases, it is due to  differences in operation motion and sequence. So a standard work sheet helps the supervisor to first check whether the operator is following the sequence and motions specified.

The concept of tact time is different and number of worker allotted to a group depends on the tact time. If the tact time is less more workers are allotted to a work cell and if tact time is more less number of workers are allotted to a work cell. But standard time for various operations performed by a work cell remain the same.

Standard inventory refers to the inventory kept before and after an operation. This inventory is kept to absorb fluctuations in output by the earlier operations or it could be the lot size inventory. Toyota production system is based on low inventory every where and therefore, the standard inventory has to be adhered to more rigorously.

Three Temporal Aspects of Standard Operations.

Shigeo Shingo describes the past, present and future aspects of standard operations.

Standard operation implies optimization of work conditions by analyzing

What is produced
Who - persons, machines, tools,and jigs
How - Method - machine speeds and feeds, man's movements
Where - Layout of the equipment and man - Work Station Design
When - Standard time, and Schedule

The Toyota production system insists that standard operation sheets are written by production people only. This refers to the past. This gives the engineer, supervisor, and workers of the shop an occasion to see what they are doing and facilitates operations improvement. So, from the idea that industrial engineer prepares the standard operation sheet, the responsibility is shifted to the production people. Industrial engineer may still make his contribution, but the final operation sheet is prepared and implemented by the production people only. It gets periodically improved even without the involvement of industrial engineers.

New workers are trained by using standard operation sheets. The workers keep referring to the sheet until they are familiar with the technique. So, there has to be a standard operation sheet by the side of the machine using which new workers are trained.

The Toyota system demands that all work is done within standard time and supervisor is charged with the responsibility. He has to train the worker. He has to determine the nonstandard motions responsible for the extra time. Thus the standard operation sheet helps in correcting deviations.

Also supervisor is responsible for improvements. A supervisor who has not improved the standard procedures in his area of work would feel embarassed in the Toyota culture.

The above is the explanation for the past, present and future of standard operation sheets by Shigeo Shingo.

Types of Standard Operating Charts

The standard operations system is more elaborate in TPS than normally described in traditional IE texts.

Capacity charts by part
For a part, the order of operations, operation names, machine numbers on which it can be processed, basic operation time, tool changing time, etc. are given.

Standard task combination
This sheet will describe the order in which individual worker's operations takes place.

Task manual
Task manuals described procedures for each element of the operation. For example, for machine operation, tool changing, set changes, etc.

Task instruction manual
It provides instructions for trainers who provide training to operators

Standard operating sheet
These sheets indicate order of tasks in an operation, cycle time, operation inventory, safety and quality instructions.

Source: Shigeo Shingo - A Study of the Toyota Production System from Industrial Engineering Point of View.

Lean Manufacturing - Research Papes and Articles - Bibliography

Articles on Lean - IIE Website Page

Emerald Insights Database

A strategic and operational approach to assess the lean performance in radial tyre manufacturing in India: A case based study
Type: Research paper
Author(s): Vipul Gupta, Padmanav Acharya, Manoj Patwardhan
Source: International Journal of Productivity and Performance Management Volume: 62 Issue: 6 2013

Application of lean manufacturing using value stream mapping in an auto-parts manufacturing unit
Type: Case study
Author(s): Harwinder Singh, Amandeep Singh
Source: Journal of Advances in Management Research Volume: 10 Issue: 1 2013

Improvement of manufacturing operations at a pharmaceutical company: A lean manufacturing approach
Type: Case study
Author(s): Boppana V. Chowdary, Damian George
Source: Journal of Manufacturing Technology Management Volume: 23 Issue: 1 2012

Four decades of lean: a systematic literature review
Type: Literature review
Author(s): Kyle B. Stone
Source: International Journal of Lean Six Sigma Volume: 3 Issue: 2 2012

Applying lean principles for high product variety and low volumes: some issues and propositions
Type: Case study
Author(s): Jay Jina, Arindam K. Bhattacharya, Andrew D. Walton

Application of value stream mapping in an Indian camshaft manufacturing organisation
Type: Case study
Author(s): S. Vinodh, K.R. Arvind, M. Somanaathan
Source: Journal of Manufacturing Technology Management Volume: 21 Issue: 7 2010

A continuing lean journey: an electronic manufacturer's adopting of Kanban
Type: Case study
Author(s): Andrew Lee-Mortimer
Source: Assembly Automation Volume: 28 Issue: 2 2008

Materials flow improvement in a lean assembly line: a case study
Type: Case study
Author(s): Rosario Domingo, Roberto Alvarez, Marta Melodía Peña, Roque Calvo
Source: Assembly Automation Volume: 27 Issue: 2 2007

Work organization in lean production and traditional plants: What are the differences?
Type: Research paper
Author(s): Cipriano Forza
Source: International Journal of Operations & Production Management Volume: 16 Issue: 2 1996

Lean production in a changing competitive world: a Japanese perspective
Type: Case study
Author(s): Hiroshi Katayama, David Bennett
Source: International Journal of Operations & Production Management Volume: 16 Issue: 2 1996

The Design of Lean Manufacturing Systems Using Time-based Analysis
Type: Conceptual Paper
Author(s): R.C. Barker
Source: International Journal of Operations & Production Management Volume: 14 Issue: 11 1994

Ebsco Database

How VIBCO Achieved Lean.   Full Text Available
Production Machining. Apr2013, Vol. 13 Issue 4, p16-20. 2p.

By: ANAND, G.; KODALI, RAMBABU. Journal of Advanced Manufacturing Systems. Jun2010, Vol. 9 Issue 1, p1-30. 30p. 1 Diagram, 2 Charts.

Key Issues for the implementation of Lean Manufacturing System.   Full Text Available
By: Upadhye, Nitin; Deshmukh, S. G.; Garg, Suresh. Global Business & Management Research. 2009, Vol. 1 Issue 3/4, p57-68. 12p. 1 Diagram, 5 Charts, 4 Graphs.

Classification scheme for lean manufacturing tools.   Full Text Available
By: Pavnaskar, S. J.; Gershenson, J. K.; Jambekar, A. B. International Journal of Production Research. 9/10/2003, Vol. 41 Issue 13, p3075. 16p. 6 Diagrams, 3 Charts.

Toyota Production System Industrial Engineering - Shigeo Shingo

Shigeo Shingo said 80% of the TPS is waste elimination that is industrial engineering, 15% production management and 5% kanban communications.

Toyota production system was developed by managers of Toyota with major contribution from Taiichi Ohno by implementing waste elimination methods advocated by industrial engineering. Taiichi Ohno specially applauds industrial engineering as profit making engineering for Toyota. Shingo builds up on the Ohno's explanation of TPS by clearly bringing out the role of industrial engineering in the development of TPS in his book.

Summary of Shigeo Shingo's Book - A Study of the Toyota Production System

Summary of Chapters 1 to 3

Chapter 4  Conclusions of Developing Non-Stock Production 

The prinicipal feature of the TPS is eliminating the total cost associated with inventory - the total of inventory carrying cost, setup or order cost and shortage cost. Hence, TPS is described as stockless or non-stock system.

Stock occur due to two reasons:

Naturally Occurrence:

Stock accumulates because of
* Incorrect market demand forecasts
* Overproduction just to be on the safe side due to likely defects
* Lot production (Batch production)
* Due technological and capacity constraints in certain processes. Heat treatment in three shifts but doing further operations in one shift.

Stock that get accumulated due to inefficiencies in the production system
* Production cycle being longer than order-to-delivery cycle.
* Stock produced in advance to take care of extra demand in the future
*Stock produced to compensate for delays in inspection and transport
* Stock produced to compensate for machine breakdowns
*Stock maintained as buffer between machines to take care of defectives
*Stock generated as per calculation of economic batch quantity to take care of high setup or order cost.

Stock reduction was carried out rationally in Toyota production system.

Three strategies can be pursued to approach the idea of non-stock production.

* Reduce the production cycle
* Eliminate the breakdowns - do preventive maintenance to make the machine available all the time for production (Total productive maintenance)
*Eliminate defect - zero defects through process improvement - detect the reasons for defects and remove
them from the process. 
* Reduce setup times and reduce batch quantity to single piece.

Chapter 5 The Principles of the Toyota Production System

The Toyota Production System is 80 percent waste elimination (Industrial Engineering), 15 percent production system and only 5 percent kanban communication.

Some Commonly Used Terms in TPS

Waste of Overproduction

There are two types of overproduction:
* Making more than required quantity for a delivery period.
* Making a product before it is needed.

Many systems are happy to produce an item before its delivery date and feel comfortable. But Toyota system does not want both types of overproduction.


JIT also means just-on-time. An item should be made available when it is required not before or after the required time.

Separation of Worker from the Machine

The whole productivity movement of Toyota was based on the fact that per worker production of cars in America was 10 times that of Toyota company. Toyota wanted to improve their productivity and therefore concentrated on reducing the time spent by a worker on the machine. Machines must work without the assistance of the worker as much as possible. Jidoka or autonomation is the name given to this activity. Along with JIT or stockless production, separation of worker from the machine forms the two pillars of Toyota Production System.

Low Utilization Rates

Toyota's machine-output ratio is two to three times  that of similar companies. This could be due to flow production systems or due to planned extra machine capacity to take care of extra demand. But one must always remember that Toyota's main goal is cost reduction and every decision in Toyota is subjected to engineering economic evaluation.

Multi-machine Handling

In 1955, 700 workers were handling 3500 machines. Hence sometimes machines are idle because worker is busy with other machines and cannot load the machines. Toyota permits machine idle times but it does not permit man idle time. The reason is that a machine costs $500 per month but a man costs twice or thrice more.

Equipment Planning and Low Operating Rates

As low operating rate is expected, Toyota buys less expensive machines. But it improves the machines to suit its requirements continuously.  Because in normal times machines have excess capacity or low operating rates,  peak demand can be handled by hiring temporary workers.

Perform Operation and Remove the Defective Part

Whenever a problem appears, Toyota insists on proper diagnosis of the root cause and demands that an operation is done to remove the replace the defective part of the process. It is not content  with the temporary cure of rework on the defective workpiece.

Fundamentals of Toyota Production System

Adopting a Non-Cost Principle

Elimination of Waste

Eliminating waste through fundamental process improvements
               Processing purpose evaluation and rationalization
               Inspection purpose evaluation and rationalization
               Transport purpose evaluation and rationalization
               Delay reason evaluation and rationalization
               Storage purpose evaluation and rationalization

Eliminating waste through fundamental operation improvement
               Setup improvement
               Auxiliary improvement
               Job allowance improvement
               Workshop allowance improvement
               Improving processing and essential operations

Ask the "five W's and one H" and "Why?" Five Times

              What -  What is being produced  - Is it required - Value engineering
               Who - Men, machines, tools and jigs used for the production
               When - Time  - Production planning also comes here.
                Where - Space (Layout)
              Why - rational for the use of everything used in production. Because it provides opportunities for improvement.
              How - The methods - motion used by man, speed and feeds used by machines

At Toyota specially, 5 Whys are used to identify root causes for defects and appearance of problems.

Mass Production and Large Lot Production are not same

Mass production is beneficial. Large lot production has extra cost. It can be reduced with SMED.

Order-based Production

Characteristics of Order-based Production

To take care of fluctuations in the orders, Toyota sets basic productions capacity at minimum demand level and handles increases through overtime and the use of excess machine capacity and temporary workers.

Overtime: There are four hour breaks between the two shifts and overtime can be given in either shift as needed.

Excess capacity: During the minimum load, many workers manage ten machines but up to 50% capacity only. As demand increases, temporary workers are hired and machines can work at 100% capacity. But machine work has to be simplified and standardized so that temporary workers can be trained in three days and they operate the machines.

Strong Market Research

Toyota does spend on market research to know market requirements. Twice in a year 60,000 people are surveyed. Five or six additional surveys are done in a year.

Production Planning

Long term planning is done.
Annual planning is done.
Monthly planning is done.
Daily planning is done. Daily planning based on actual orders. The actual orders are informed to the first stage of assembly section and they draw the components as required from component supply stages.

Toyota's Supermarket System

In the supermarket system of Toyota, stocking is triggered by actual demand for the components for a daily requirement.

Differences between Ford and Toyota Systems

Large lot versus small lot production

Mixed model assembly in Toyota system

More consistent one piece flow in Toyota system

Chapter 6  Mechanics of the Toyota Production System

Improving the Process - Schedule control and Just-in-Time

Toyota makes efforts and reduces production cycle.

Seven Principles for Shortening the Production Cycle

Reduce process delays
Reduce lot delays
Reducing production time
Employ layout, line forming, and the full work control system
Synchronize operations and absorb deviations
Establishing tact time
Ensure product flow between processes

Adopting SMED

Elimination of Defects

Inspection to prevent defects must be practiced.

100% inspection must be adopted.

Poka-Yoke has to be used as a means for zero defects.

Eliminating Machine Breakdowns
It is also process improvement in TPS. Workers are asked to stop  a machine if there is some trouble. Supervisors are given training and are urged to try to keep machines running. When a trouble appears, a visual indication is given and all try to take care of the problem. Preventing recurrence is the motto of TPS.

Chapter 7 Mechanics of the TPS

Improving Process - Leveling and the Nagara System

Segmented Production

Making production plans for half a month(H), ten days (T), week (W) and Day (D) are segmented production plans.

Mixed Production and Tact Time

Toyota combines product A with 30 Seconds and product B with 25 seconds and specifies 55 seconds as tact time for A+B.

Nagara System

Smooth production flow, ideally one piece at a time, characterized by synchronization (balancing) of production processes and maximum use of available time; includes overlapping of operations where practical. A nagara production system is one in which seemingly unrelated tasks can be produced simultaneously by the same operator.

Nagara is multi-machine handling in a process or flow system. The operator works with two or more different machines.

Chapter 8 Mechanics of the TPS

Improving Operations

Operations concern the flow of equipment and operators in time and space. Improvements in operations have long been emphasized in the Toyota Production system.

Components of Operations

1. Preparation and after-adjustment
2. Principal operations
3. Marginal allowances

Preparation and After-Adjustment

Reduce them through SMED

Margin Allowances

Personal allowances - For fatigue and personal needs
Non-personal allowances -
Operational allowances: Oiling, clearing away chips etc.
Workplace related: parts arriving late and machine breakdowns

Standard Operation and Standard Operation Sheets

Standard operation implies optimization of work conditions by analyzing

What is produced
Who - persons, machines, tools,and jigs
How - Method - machine speeds and feeds, man's movements
Where - Layout of the equipment and man - Work Station Design
When - Standard time, and Schedule

There has to be a standard operation sheet by the side of the machine using which new workers are trained.

The Toyota system demands that all work is done within standard time and supervisor is charged with the responsibility. He has to train the worker. Also supervisor is responsible for improvements.

Types of Standard Operating Charts

Capacity charts by part
Standard task combination
Task manual
Task instruction manual
Standard operating sheet

The topic of standard operations is discussed in more detail in
Standard Operation and Standard Operation Sheets in Toyota Production System

Improving Methods of Operation

The operation, which is a man-machine combination can be improved through:

1. Improvements in human motions
2. Improvement in machine movements - increasing machine cutting speeds, reducing time through simultaneous cutting on multiaxis machines, and using multiple turret heads to shorten tool replacements.
3. Mechanizing human motions.

Improving human motions

Motion study can be used to reduce the operation time or the operator time. Motion study improves the movements or motions made by the operator and also improves the arrangement of materials and tools. 5S movement of Japanese industry is basically the offshoot of principles of motion economy.

Items must be arranged neatly, they must be easily accessible and they must be uniformly aligned.

Improvements in Machine Movements

Examples include raising output by increasing machine cutting speeds, reducing time through simultaneous cutting on multi-axis machines, and using multiple turret heads to shorten tool replacement time. This could involve using faster cutting processes like milling in the place of slower process like shaping.

Mechanizing Human Motions

In Toyota, first the human motions are optimized and then mechanization is attempted. Whenever mechanization is thought of its economics are thoroughly investigated. Toyota insists on kaizen - good change.

Machine Layout and Worker Efficiency

Workers are stationed with in a U layout so that they can easily help one another in case of need. Toyota encourages workers to assist each other in case of need or necessity. It discourages island mentality.  The system requires each worker to learn the operations performed at the two processes adjacent to his or her own and help the others when needed.

Multiple Machine Handling Operations

In 1955 itself, Toyota operated 3,500 machines with only 700 workers.  So one worker operates five machines on an average. In recent years (1981), Toyota managers started advocating multi-process handling. In multiple machine handling, the worker may handling the same type of machines. But in multi-process handling, the worker will handling multiple machines in accordance with the flow of operations or process. The capability of multi-process handling by a worker improves the flow of the process and also improves productivity.

Chapter 10. Elimination of the Seven Kinds of Waste

1. Processing

Value analysis and engineering needs to be made. Also purpose analysis needs to be done.

2. The waste of making defective products

Poka-yoke needs to be used to prevent defects. Self inspection and successive inspection are to be promoted.

3. Transport

Improve the layout and reduce the need for transport.

4. Delay

Use small lot sizes and minimize delay for the jobs. Allot multiple machines to workers such that there is no waiting time for them. If needed machines can be idle.

5. Inventory

Use SMED and one piece flow and reduce production cycles.


6. Wasted Motions

Do motion studies

7. Overproduction

Reduce production for inventory rationally. Use SMED and decrease lot sizes. Improve informative inspection and avoid defects. Maintain machines such that there are no breakdowns and machines are available production all the time. Produce just-in-time for stockless production.

Chapter 12  - Introducing Toyota Production System

Introducing and Implementing the Toyota Production System - Shigeo Shingo

Friday, April 4, 2014

Estimating Machining Time for Turning

In the case of turning the formula for machine time is

T = [L+A]/[frN]

Where T = machining time in minutes
L = length of the workpiece
A = an allowance for tool approach and exist, normally 2 to 5 mm
fr   = feed rate (mm per revolution of the workpiece)
N = revolutions of the workpiece in rev per minute