There are many methods for improving the performance of organizations and a significant part of them are "Lean" ones, derived from the "Toyota Production System" or theorised in the books by J. Womack, T. Jones and D. Roos ("The machine that changed the world" and "Lean Thinking").
As is often the case, some methods have multiple origins, have been borrowed, adopted or modified over time and are therefore not all original "Lean" methods.
The important thing is not to know the exact origin of these techniques but to apply them well according to the context in order to reap the benefits.
The presentation below therefore presents the main "Lean" methods in a synthetic way without worrying about their true origin, even if it is often described.
The Lean method of the "five whys" would have been designed by Sakichi Toyoda. It is one of the important methods used by Toyota to solve problems. The principle is not to stop at the first cause of a problem (the first why) but to analyze the problem until the root cause or causes are identified.
It is in fact more of a principle than a method of cause analysis because it is neither sufficiently structured nor'exact' (why 5 and not 4, 6? The root cause may very well be discovered in the 2nd).What are the benefits?
It has the merit of simplicity to show that it is not necessary to stop at the obvious and make a rigorous analysis of a problem before being able to define solutions.
The 5S is a cleaning and storage technique whose five letters mean:
- Seiri: Sort, separate the necessary from the unnecessary
- Seiton: Set in order
- Seiso: Shine, clean
- Seiketsu: Standardize
- Shitsuke: Sustain, self-discipline
These definitions are a representation of the meaning that these words convey in their use, and keeping the "S" as a mnemonic because their literal translation is slightly different.What are the benefits?
The 5S Lean method is actually much more than a cleaning technique. When it is used according to its true intentions, the benefits are multiple:
- cost reduction by eliminating unnecessary tools or parts (Seiri) or standardizing them (Seiketsu)
- simplifying work and increasing productivity by reducing search times (Seiton)
- prevention of breakdowns by inspecting tools or machines during cleaning (Seiso) and detecting any anomalies
- reduction of the risk of accidents, for example by avoiding the cluttering of parts, or places made slippery by oil stains
You can see the 5S practical implementation method
The word of Japanese origin is the combination of the two symbols 行 (go) and 灯 (light), which can be interpreted as "going where the light is".
In its professional application, the andon is a luminous display triggered when a problem is detected on a workstation in order to correct it as quickly as possible.
It can be triggered by an operator or automatically by the equipment where the problem occurs. Color codes can specify the type or level of urgency of the anomaly in order to conduct appropriate activities.
It was initially designed for large production workshops where visibility is very important. But it is applicable to other situations, such as call centres, and also in its computerised version where warning lights can be displayed on the PCs (or mobile) of the persons concerned.
What are the benefits?
It allows you to immediately and simply where a problem appears in order to correct it as quickly as possible. As it is visible, it can inform all concerned simultaneously so that everyone can intervene according to their responsibilities.
Autonomation or Jidoka
The Jidoka (自働化) is the automatic shutdown of a machine or equipment in case of defect detection. It is a word coined in 1896 by Sakichi Toyoda when he designed the first weaving machine that automatically stops when the yarn breaks; it means "automation with human touch" and has been translated into English by autonomation (contraction of automation and autonomous); it frees the human from the machine since it no longer needs constant monitoring if it stops itself.
It actually carries two important concepts in the original system of the Toyota Production System:
What are the benefits?
- the release of the human from the machine that allows an operator to operate several machines at once
- the "built-in Quality" by detecting quality problems as early as possible in order to solve them quickly; the complete concept even consists in identifying the root causes to correct them definitively.
Labour savings by allowing an operator to operate several machines at the same time.
Savings in scrap or retouching, as well as an increase in induced productivity (first time right product) by correcting quality problems as soon as possible and preventing them from reoccurring.
Continuous flow production consists of producing only one product at a time at each step of the process, unlike batch production, which consists of producing several products at a time.
This seems at first glance less efficient than batch production because it does not allow to benefit from any possible scale effects of the latter.
However, it minimizes stock levels of work in progress and reduces production cycle time, as each product does not have to wait for others before moving on to the next production step.
Moreover, unlike batch production, which can mask certain problems (thanks to intermediate waiting times), it requires the elimination of these problems (under penalty of stopping production instantly) and ultimately to make production more efficient.What are the benefits?
Lower stock levels and shorter production cycle times.
This is probably one of the most emblematic Lean method. Gemba, is a Japanese word (現場) that literally means "crime scene". Toyota, which initially used this term, has in fact replaced it with the term "Genchi genbutsu" which has a more positive connotation and means "going where the problem is encountered". The term most commonly used in the industry today is actually the "Gemba walk"...generally explained using the translation of the Genchi genbutsu.
Behind the differences in terms, there is a more important difference in philosophy. Whatever the term, it is the visit of a manager to the workplace. But Gemba, in its original version, emphasizes the inspection and verification of facts in order to make the right decisions. While the "Genchi genbutsu" version, which is closer to the American version of "management by wandering around", insists more on the informal side and listening of the employees who are visited.
Of course, a third approach can combine the first two.What are the benefits?
A more detailed, accurate knowledge of working conditions and possible problems to be solved, and therefore better decisions.
Better mutual relations and understanding between managers and their teams.
As its name suggests, the principle of Just-in-Time consists in each of the elements necessary for an operation on a product at a workstation arriving just at the moment when it is necessary for this operation with the right quantity. It is more a Lean principle than a Lean method because the activities and tools required (the method) to achieve Just-In-Time are quite complicated in practice; the method uses several techniques such as Kanban, Takt time or production smoothing (Heijunka) but may also require perfect coordination with external suppliers.What are the benefits?
A reduction in the amount of products and parts outstanding.
In an induced way, the JIT contributes to the elimination of losses, the simplification and smoothing of production.
Heijunka (Level Scheduling)
Heijunka translation is levelling, which means smoothing the planning or workload in the industrial world. This method is fundamental to the success of "continuous flow" production in practice. It compensates for the fact that, in reality, orders rarely arrive at a regular rate.
There are two types of levelling:
- volume levelling: as the orders are of different quantities each day, the smoothed production produces the average of the orders over a given period,
- levelling by product type: smoothing is a little more complicated, it is a question of combining each day the different products according to their production time to arrive at an identical (or almost identical) average time each day.
In practice, the two methods are combined. A visual means has been developed, the Heijunka box: it consists of boxes, each representing a type of product (in column) and a day of the week (in row), the number of sheets per box is the number of products of the type considered to be produced for that day; the production of the day is the sum of the products in the same column.What are the benefits?
Allow continuous flow production when orders are not regular, i.e. in most cases.
The literal translation of Hoshin Kanri (方針管理) is "management of the direction". It is a method of deploying corporate policy or strategy, or in a broader sense of deploying major changes such as transformation programs. It is the opposite, or rather a complement to continuous improvement. It is often considered a Lean method though its origins are a mixture of management by objectives (by P. Drucker), the teachings of W. Edwards Deming (notably known for the PDCA) and those of Joseph M. Juran in Japan where it was developed, notably by a subsidiary of Hewlett-Packard.
This method has three pillars:
- a cascaded deployment based on the definition of the vision: the management sets the main directions that are applied in the whole organisation ( "top down" process)
- an iterative and participative process at each hierarchical level: allows good understanding, adaptation to reality and appropriation by the teams at each level; this process is often called "catchball" (from a child's game with ball exchange)
- Short and long PDCA cycles: allows to correct and improve the deployment over several time horizons.
The method consists of 7 steps:
- Define the vision
- Define strategic or transformational / breakthrough objectives
- Define annual objectives: translate previous objectives, which are long-term objectives, into annual objectives
- Deploy annual objectives: consists of applying the previous objectives (which are from the general management level) to the lower levels in a way that is adapted to the responsibilities and activities of these levels
- Implement annual objectives: implementation really begins with a measurement of results against objectives
- Monthly review: PDCA cycle to improve execution
- Annual review: PDCA cycle to improve the whole, starting with the definition of the vision
One tool used is the Hoshin Kanri matrix or X matrix, which synthesises the relationship between the Breakthrough Objectives, annual objectives, breakthrough priorities and quantified concrete objectives.What are the benefits?
The main benefit is the successful implementation of the vision in the organization. It implies a good alignment of the organization, a pragmatic approach adapted to the operational modes and a commitment of the staff to the vision and operational modes.
Kaizen is probably the most known Lean method. Kaizen (改善?) is the combination of kai and zen that means "change" and "good". This is simply what we have translated as "continuous improvement". It is therefore not a method but a principle or philosophy that is at the heart of Lean.
Kaizen (chantier) - Kaikaku
In the West, the word Kaizen is often used in the context of a "Kaizen event", or "Kaizen Blitz". It is actually a rather curious translation because it is the opposite of Kaizen (which implies progressive improvements) in making radical changes; the Japanese more precisely call it by another name, Kaikaku (改革) which means reform.
A Kaizen Blitz is generally a one- to five-day workshop (the entire week), focused on a specific area and theme, with the objective of making a significant change.What are the benefits?
Achieve visible and faster results than with the more traditional continuous improvement.What are the risks?
It is important to mention the risks here. The approach itself is highly visible and mobilizes a significant number of people. Any failure can therefore be fatal and undermine the credibility of the method.
Worse still, it can be used and perceived as THE continuous improvement approach that becomes a succession of flash actions and can then discredit Lean as a whole.
Kanban (看板) means "sign" or "card" in Japanese. This is the key method for implementing "pull" continuous flow production.
It is used to trigger the production of parts between workshops, starting from the lowest workstation and working up to the upstream workstations.
The principle is as follows:
- a card (Kanban) is attached to each part to be processed at the downstream workstation
- when the downstream station has completed its operations on the part, the card returns to the card table (Kanban board) of the upstream station
- for the upstream station, the card is a "production order" and it starts its operations when there is a card in its card box.
- there can be several cards in the Kanban board and the production of the upstream item starts when the number of cards exceeds a certain level; but this level must be minimal otherwise it increases the stock of work in progress.
To be implemented, it requires that the entire production perimeter concerned be organised in a continuous "pull" flow.What are the benefits?
A visual method for planning an entire workshop without the need for expensive MRP software or planning staff.
It is simple to implement once the entire system is designed to operate as a pull flow.
The PDCA originated from a seminar sponsored by the Japanese Union of Scientists and Engineers (JUSE), where W. Edwards Deming presented a modified Shewhart Cycle. It is a method of designing and manufacturing a product in accordance with specifications; JUSE, and in particular Kaoru Ishikawa, has transposed it to be used as a more general method called PDCA. It has become a fundamental element of Lean continuous improvement principle. It is also called the Deming Wheel. Its four steps are:
What are the benefits?
- Plan: plan the actions, after defining what you want to implement and the objectives
- Do: carry out the actions
- Check: monitor the achievement of actions and objectives, understand the results
- Act: Act, implement corrective or improvement actions
The benefits depend on the context and objectives of the use of the PDCA. In an efficiency context, it makes it possible to implement actions in order to obtain the expected results; in a more experimental context, it makes it possible to test an idea or concept and modify them after a learning phase. More generally, it allows for continuous improvement.
The Poka-Yoke (アンチエラー) is a mistake-proofing system; it prevents assembly, assembly, connection or even procedural errors. Three types of system can be distinguished:
- mechanical: two parts, due to their mechanical design, can only be assembled or connected in one direction.
- warning: an audible or visual signal is triggered if an operation is not performed
- procedural: a system blocks the continuation of operations if an operation is not performed or not performed in the right order
Single Minute Exchange of Die (SMED)
It is a Lean method developed by Shigeo Shingo at Toyota. Its objective is to reduce tool changeover times in production as much as possible.
The method consists of five steps
- Identify the operations performed: all operations performed must be identified and measured, including waiting times
- Determine internal and external operations
- internal operations are those specific to the change operation that require production to be stopped
- external operations are those that can take place before or during production: preparation of parts or tools, presettings...
- Group external operations together: this grouping already reduces production downtime by eliminating the times of these operations from downtime
- Reduce the time of internal operations: review in detail each of these operations and determine if they can be deleted, modified, accelerated...
- Reduce the time of external operations: has no direct impact but can nevertheless improve efficiency or reduce costs
It will of course be possible to complete this method with standardisation or continuous improvement steps.
Although it is a fundamental pillar of the Toyota Production System and Lean, it must be recognised that the father of standardization is Henry Ford. It consists in standardising processes, operating procedures, tools and also by extending parts and components. What are the benefits?
They are to improve the reproducibility and stability of production, to facilitate the learning or sharing of methods between teams as well as the interchangeability of people between teams, and finally to reduce the cost of manufacturing standardised tools or parts.
Takt comes from German and means cadence.
Takt time is not strictly speaking a method; it is the essential measuring element of the continuous flow production method. This is the production rate of each product, which must be identical in theory to the sales rate. Ideally, if all production steps are well balanced (according to the Heijunka method), each at a duration equal to Takt time.
Total Productive Maintenance (TPM)
Total Productive Maintenance was developed in the late 1960s at a Toyota parts supplier, Nippondenso, and formalized by Seiichi Nakajima, Director of the Japan Institute of Plant Management (JIPM).
This method is based on two key principles, included in its name:
- Productive: to carry out as much as possible the maintenance without stopping production
- Total: include all factors influencing the proper functioning of the machines and involve everyone
The JIPM has defined eight pillars of TPM:
What are the benefits?
- Autonomous maintenance: simple operations (cleaning, lubrication, inspection, etc.) carried out by production operators and preventing breakdowns or identifying anomalies as soon as possible
- Case by case improvement (Kobetsu-Kaizen): it is the equivalent of Kaizen in the TPS method
- Scheduled maintenance: it prevents breakdowns through preventive work
- Training and knowledge management: training of maintenance technicians and operators allows for better maintenance
- Maintenance from the design stage: maintenance is taken into account in the design of machines or products to facilitate maintenance operations
- Quality Maintenance: maintenance contributes to quality by avoiding or limiting defects due to machine malfunction.
- Health, Safety and Environment: this pillar ensures a good environment for employees and helps to develop a culture that encourages attention to equipment.
- Office maintenance: ensure that the support functions understand the challenges of maintenance and can provide support in addition to developing their sense of improvement on their own processes.
TPM has three main benefits:
- the involvement of all in maintenance and therefore better prevention combined with control of maintenance costs
- reduce machine downtime, in particular through maintenance without stopping production
- a holistic approach with consideration of all factors
Value Stream Mapping (VSM)
The value stream mapping is an analysis tool that makes it possible to identify and visualize in a synthetic way all the physical and information flows of a process.
The synthetic and visual aspect is possible thanks to the use of standardised symbols and a description that must remain at a macroscopic level without being exhaustive.
Several pieces of information are characteristic of flow mapping:
- the joint representation of physical and information flows (in particular production orders or orders)
- the representation of the travels and stock stages in addition to the other pure production stages
- the identification of key volume and duration figures for each step
- the cumulative time line by identifying the processing times (including inspection times, even if they are not value-added times) and the times between operations (movements, waiting, stocks)
- identification of problems
A Value Stream Mapping can be performed for production processes as well as for service processes, product design, software development or others.What are the benefits?
The simple visualisation allows an easy exchange between the people concerned to have a common vision of the reality of the process.
In particular, it makes it possible to visualize the total cycle time and to understand that it is the share of production time in relation to inter-operation time.
It is an ideal basis for identifying areas to be investigated in more detail to understand malfunctions, reduce non-value-added activities and reduce stocks of work in progress.
One of the fundamental principles of Lean is the reduction of waste, which is also more of a Lean principle than a Lean method. According to Taichi Ohno there are three types of waste:
- Muda: activities without added value for the final product; some of its activities are nevertheless necessary, such as quality controls or adjustments
- Muri: excessive or too difficult activities
- Mura: variability undergone
The reduction of waste primarily concerns unnecessary Muda. There are 8 types of Muda to reduce:
What are the benefits?
- Unnecessary transport or travel (materials, parts, products, documents)
- Unnecessary motion
- Defects and rejects
- Waiting time
- Underutilisation of skills; this waste was added after the first seven initially defined by Taichi Ohno
The identification and systematic reduction of waste is a major lever for simplifying processes and reducing their variability.