7 types of waste (Muda)
Waste is any kind of activity that uses resources but does not increase value for the customer. Therefore, the elimination of waste offers companies the opportunity to reduce costs and increase the efficiency. In the classic Lean-Production-Doctrine Lean-Production-Doctrine, according to Taiichi Ohno, the father of the Toyota Production system, seven types of waste are classified that do influence each other. These can easily be memorised using the mnemonic TIMWOOD.
|Lean approaches to avoidance|
Whenever material is transported, costs for personnel and energy are incurred and no added value is created. Hence, it should be checked if transport distances could be shortened or avoided by e.g. placing workstations or by pulsing and linking work steps.
Inventories are an important part within the entire value chain: initially as raw materials, then as "Work in Process" (WIP) and finally as finished products. However, inventories over and above the current needs are waste, as they cause costs in logistics and tie up capital. Standardised and stable processes reduce the necessity of high inventories and reduce waste through transport.
Unnecessary movements such as handing of tools, or walking to a material dispensing station, lower the productivity, can cause poor posture and thus strain the musculoskeletal system of the employees. At this point ergonomic principles in work place design must be acknowledged in order to increase the efficiency of employees, and to avoid work accidents and loss of quality. The consequences of unnecessary movements often are waiting and transportation.
Waiting for e.g. the end of a processing cycle of a machine or the unscheduled waiting for material replenishment or because of a disruption is waste, as no value is added during this time. The most severe impact is the increase in the lead-time for manufacturing the products. Waiting times can also influence the motivation of - under-utilised- employees. They can be avoided by better process planning, but can also be bridged by multi-station handling or job enlargement of the employees
Over-production production counts as waste, since more is produced than is purchased, resulting in inventories and therefore respective costs (warehousing and inventory management) and liquidity losses (due to tied up capital). Despite the value creation, it is not certain, whether the goods can be sold and thus become turnover relevant for the company. The cause, on the one hand, is often the so called "optimal batch size", in which the ratio between the set-up costs and inventory costs for pending production orders is (in many ERP/MRP systems automatically) optimised - even if there is no real sales for the calculated quantity. The reason on the other hand is the optimisation of capacity utilisation, since investment intensive machines and plants should not be unproductive if possible.
Wrong processes/ technologies
Waste is caused by outdated or immature processes as well as by over-engineering. Processes or manufacturing methods without necessity for the finished product become overly complex. Therefore, processes should be reviewed, continuously improved and modernised in order not to waste resources and to increase production.
Rejects or rework due to lack of quality is obviously waste, as the value creation has already (partially) been completed when the product is identified as faulty by inspection. The causes often are malfunctioning machines or employees making mistakes, defective third-party components or uncalibrated measuring tools. The goal is to eliminate the cause, reduce the reject rate and provide the desired quality.
DMAIC stands for the core process of the Six. Sigma approaches in quality management and describes its phases Define-Measure-Analyse-Improve-Control. The DMAIC process is used to make existing processes measurable and to improve them sustainably in terms of to a high customer satisfaction at the lowest possible costs. DMAIC combines known approaches and methods into one systematic approach. For this purpose, the tools are linked across phases, therefore structuring and systemising the project chronologically.
Define – What is the problem?
In this phase, the actual state is documented and it is defined, who the customers of the process are and what needs the process is meant to fulfil. Based on this, the performance characteristics of the process that are critical for meeting the customer expectations, are defined. Additionally, project parameters such as scope, boundaries and timeframes are set.
Measure - How can the impact be measured?
In the phase of measuring, it is determined how well the process really fulfils the customer requirements. Keeping this in mind, the process is initially divided into sub-processes and visualised (Process Mapping). Based on this, possible influencing variables can be determined and methods and instruments for the collection of data from the individual process steps can be set. To ensure the measurement capability the so-called Measurement System Analysis (MAS) is used. As a result of this phase, an understanding of the situation to be improved based on real facts is obtained.
Analyse – What are the cases of the problem?
The aim of the analytical phase is to identify the causes of the deviation from defined performance goals. For this purpose, process- and data analyses are carried out. Instruments used are, besides brainstorming, Ishikawa-Diagrams, FMEA as well as statistical methods.
Improve - How can the problem be eliminated?
During this phase, solutions fare sought for the problems identified in the phase of the analysis. Creative techniques, such as Brainstorming, Brainwriting, Mindmapping or Morphological Boxes can be used during this phase. The possible solutions will be examined and evaluated against standards (legal requirements, regulations, environmental guidelines etc.) and feasibility criteria. The most advantageous solution will be implemented.
Control - How is the improvement permanently embedded in practice?
The last phase is used to anchor the achieved improvements and new procedures by standardisation and documentation. The effectiveness of the measures will be continuously monitored with the developed measuring systems in order to initiate appropriate corrective measures when deviating from set goals.
The A3-Method, also called the A3-Report, is a form on a Din-A3 sheet. The A3-Report is used in quality management to identify problems and develop solutions for process optimisation. Apart from texts, it also contains diagrams and other graphical elements to present information clearly and to enable a deepened understanding of contexts.
With the help of theA3-Report, employees learn to identify, analyse and solve problems themselves. - All with continuous improvement (CIP) in mind. The special feature of the A3-Report is that it makes the thought process for problem solving transparent, as users go through the individual analysis and action steps for problem solving one after the other, thus better understanding the problem and being able to design and implement sustainable solutions for a problem.
The A3-Report goes back to the industrial engineer Joseph Juan about 60 years ago he recommended that Japanese to managers noted problem solutions, decision-making principles and strategies for clarity’s sake on one piece of paper. Toyota followed this recommendation and chose the DIN A 3 format - hence the name.
Structure of the A3-Report
When solving a problem and implementing a new standard seven steps are made. On the left hand side of the form the four analytical steps that relate refer to the planning phase of the PDCA Cycle (plan-Do-Check-Act), also called the Deming circle are noted. The right hand side reflects the Do-Check-Act phases (execution, review, intervention) of the PDCA cycle.
Steps of the analysis in detail:
- 1.Background: the problem and its effect in relation to the achievement of a corporate goal is phrased in a clear and understandable manner for all persons involved. The importance of the problem and the reason for the pursued solution to the problem must be comprehensible.
- Current situation : The description of the current situation contains detailed facts, often in form of easy to understand graphic elements (pictures, graphs, charts or tables) to highlight the relevance of the problem for the company, to identify its place of origin and to show possible hurdles in its elimination.
- Target situation: the pursued target situation must be clearly defined as a goal. The objective makes the implementation of measures to solve the problem easier and leads to an effective solution as all persons involved compare different approaches with each other based on key figures for achieving the goal already when drawing up an action plan and question if those figures are suitable for the purpose.
- Analysis of causes: the aim of the analysis is to determine factors that have direct influence on the problem. From the influencing factors, approaches for effective measures can be derived. A fishbone diagram (also called an Ishikawa diagram after its developer), which is used to collect the possible causes of problems, often help in the analysis of causes.
- Countermeasures: All measures, that are to be implemented to eliminate the causes of the problem and to improve the actual state in the long term, are listed here. It must be clearly indicated: What is the (partial) problem that the measure is intended to solve? How will the problem be solved? Who is responsible for it? When will the measure be implemented? Where will it be carried out?
- Effectiveness: In this step it is examined how successful the measures were and what contribution they made in the achievement of goals. The graphical representation of the measured impact makes it easier to understand.
- 7. Standardisation and follow-up: During the follow-up the entire process is evaluated. Measures are defined to secure and advance the achieved improvements through standardisation. Successful countermeasures are standardised. Additionally, consideration is given to how the gained insights can be used and applied in other problem and work areas.
Advantages of the A3-Method
The advantages of the A3-Method are that
- the causes of problems are quickly recognised, as the user must deal with the problem at hand intensively.
- that the situation is made understandable due to the clear presentation. This eases the targeted development and implementation of strategies in the continuous improvement process.
- teamwork is promoted, as all participants are involved in the processing of the A3 report and are encouraged to deal intensively with the problem, its effects and possible solutions.
- the form can be adapted to the individual situation at hand. This allows the development of targeted and efficient solution strategies as well as the control of projects and meetings. Projects can be coordinated by linking several documents.
- the sense of responsibility to independently solve and analyse problems and execute complex tasks is strengthened.
Working with the A3-Report requires particular abilities from everyone involved in the process. Especially managers have to deal more intensively with value-added processes and have to see themselves as mentors for their employees. Despite the initially added burden, managers will be relieved in the medium term due to the independent problem solving by employees. The more competency and routine the employees gain in solving problems, the more complex tasks can be delegated to the employees by the management.
In order for companies to successfully cope with unknown, changing challenges, they must be able to adapt strategies, structures and processes to the actual circumstances at short notice. To keep dynamics and stability in balance in a changing environment in such a way, that the business mission can be fulfilled in the long term, requires a new way of thinking and working at all levels of the company. Agility is asked for.
The origin of agility lies in the systems theory of organisations of the 1950s. According to this, the functionality of organisations is based on the AGIL -scheme : Adaption (the ability to react to changing external conditions), Goal Attainment (define and pursue goals), Integration (creating and securing cohesion and inclusion), as well as Latency (maintaining fundamental goals and values)
The concept of agility was further developed in three directions:
1. Agile manufacturing
The concept, which emerged in the 1990s, is based on a quick product development (Simultaneous Engineering), multi-functional teams and the continuous improvement of the production process. The idea if industry 4.0 is also based on this approach: processes are interrupted and adapted, projects are repeatedly restarted, taking for example changed customer wishes and market requirements into account; processes and projects can also be questioned and eliminated, or terminated.
2. Agile software development
Since 2001, according to the manifesto for Agile software development, the individuals and interactions are super-ordinated to processes and tools: working software is more important than comprehensive documentation, the collaboration with customers more important than agreed contracts, reacting to changes more important than following a plan. The incremental delivery of results enables feedback and correction. A lean method that is widely used in this context is Scrum.
3. Agile organisation
Agile organisations are based on transparency, dialogue, trust, freedom of decision-making and short channels for feedback. Knowledge is openly shared, mistakes are constructively addressed, and status symbols are eliminated. Employees are involved in personnel planning and staff development is not just based on specifications, but also on "peer feedback" from the teams. The agile organisation does not only refer to production processes or software development, but focuses on the transformation of company divisions or the entire company.
In order to develop and strengthen agility within the company, the following aspects have to be considered:
- Creating framework conditions for agile approaches
- Focussing on results, not processes
- Creating a corporate culture, that allows errors
- Encourage the strengths of employees.
- Building trust among employees
- Delegate responsibility to employees
The Plan-Do-Check-Act-Cycle (PDCA), also known as Demingkreis or Shewhart-Cycle, as a model for optimising the quality management in companies. It is an integral part of the Lean-Management philosophy and an important prerequisite for continuous improvement in the development and manufacture of products and services or for the root cause analysis.
The four phases of the PDCA Cycle
Of all the tools for quality improvement, the PDCA Cycle is the most important. It describes the basics of an improvement process and structures it into four phases.
Phase 1: Plan (planning)
IIn this phase the problem and the actual state are described, the causes for problems are analysed and the target state is enunciated. In addition, measuring values for achieving the target state are defined.
Phase 2: Do (implementing)
During this phase, measures that were defined in the planning phase are implemented. At this stage mainly those employees are involved who participate in solving the problems. It is important that all activities of the Do-Phase be documented.
Phase 3: Check (verifying)
In this phase, the experience gained and results achieved in implementing the measures are reflected upon and the measures are adjusted if necessary.
Phase 4: Act (acting)
IIn the final phase of the PDCA Cycle, the experiences gained during the process of problem solving are evaluated and standards for future action are derived from it. If, during the Act-phase, it becomes clear, that the goal has not been achieved, the PDCA-Cycle starts anew.
The PDCA-Cycle in practical application
The continuous application of the PDCA-Cycle is necessary for a sustainable optimisation of the quality management within the company. It is a precondition that the management level pursues a strict quality policy and passes this on to the employees.
Order and cleanliness, standards and self-discipline at the work place are simple but crucial prerequisites to fulfil one's tasks efficiently and to improve the execution further. Therefore, many optimisation projects therefore start with the application of the 5S-Method.
What does 5S represent?
- Sorting (Seiri): sorting out unnecessary things
- Systemise (seiton): arrange all tools, floor areas, shelves and cabinets, as they are needed. Pay attention to ergonomics and efficiency.
- Cleanliness (Seiso): Define cleaning standards and work off according to checklists. Since employees clean their workspaces and utensils themselves, deficiencies are noticed and systematically taken care of.
- Standardise (Seiketsu): The new condition or the improved process will become a binding commitment after every implemented improvement. Standards reduce search times and improve the execution of work by becoming routine.
- Practice self-discipline and improve constantly (Shitsuke): maintaining order and standards need to become the personal basic attitude of employees. Only through permanent self-control and discipline is it possible to abandon old standards and set new standards.
What are the benefits of applying the 5S-Method?
Using the 5S-Method, an improved work organisation is systematically introduced and standardised. The consistent application saves time and resources and is part of a continuous improvement process(CIP)
The advantages in detail:
- Reduction of search-, setup- and travel times
- Reduction of stock in tool and auxiliary materials
- Improved sense of responsibility and discipline of employees and managers
- Increased transparency of the operational processes
- Better work- and process safety
- Increased quality due to error avoidance
- Basis for preventative maintenance and methods such as Total productive Maintenance and setup time optimisation
General conditions for successful implementation
The effort required for the implementation of and training in the 5S Methods is low, therefore results are usually seen in the medium term. That is why the 5S Method is ideally suited as an introduction to process optimisation. However, it needs to be noted that the implementation of the method is not a one-off, but it is crucial that it is anchored to the corporate culture and integrated into the daily working life of the employees. Additionally the method should be equally spread across all employees, management included.
Kaizen is a Japanese management concept that aims at the gradual and continuous improvement and perfection of processes. It combines the Japanese Words “Kai", representing change, and "Zen" representing „for the better". Kaizen is generally not applied globally, but rather in the area of activity of every individual on every level.
In Europe, Kaizen has been applied since the early 1990s, mostly under the term of "continuous improvement process" and is based on the following guiding principles:
- Good processes to achieve good results
- Taking measures to contain and correct the basic causes of problems
- Documentation of the current situation
- Integration of all employees
Key fundamentals of Kaizen
If a proposed improvement suggestion is suitable for a company, it will be defined as a standard and integrated into the existing processes. The PDCA-Cycle transforms therefore to SDCA (Standardise, Do, Check; Act). As soon as the process is completed, a further improvement is addressed.
Criticism is viewed as an opportunity for continuous improvement. Therefore, every employee should be encouraged to come forward with suggestions for improvement. The company should take up these suggestions constructively and try to implement them in the best possible way. This results in a continuous cycle of planning, doing, checking and improvement. (in short: PDCA Cycle: Plan-Do-Check-Act)
JEach company defines its own standards of quality, which will be transferred onto the quality requirements for (of) activities and processes.
In Kaizen, the company is focused on customers and their needs and expectations. A distinction is made here between external and internal customers. External customers act outside their own enterprise. Internal customers on the other hand are within the company e.g. their own colleagues, who receive the service. Since every activity in the company is regarded as a customer-supplier service, the company thus appears to be very customer-oriented. At the same time, this corporate culture requires each employee to critically examine, analyse and improve his or her own performance.
The process orientation helps, due to the continuous improvement, to make processes manageable controllable. An improved process automatically leads to better results. The process optimisation therefore has to take place on a regular basis, enabling flexible and quick reactions. Adhering to these guidelines increases value creation, reduces waste, and defects at the same time.
Kaizen purses the following goals:
- - Guaranteeing quality from the beginning
- - Standardisation dof work operations by identification of tasks and correct adherence to self-imposed standards
- Avoidance of waste of resources ( time and material)
- - Independent identification and elimination of weak spots
Kaizen involves a cooperative management style. This means that leaders and employees work closely together both in the development of ideas and in the implementation of projects, and complementing each other in their competencies. Kaizen also has other aspects: intensive transfer of information from top down as well as vice versa. In addition, there is a joint, clear formulation of objectives and an understandable consensus instead of individual decisions made by the superiors.
The ideal for Kaizen means tis to establish qualified, active, responsible and creative employees in the company. They receive a differentiated and individual recognition and financial remuneration for their performance. Kaizen therefore offers the opportunity to improve process structures within the company. Thanks to the continuous optimisation, this is reflected in quality, in the motivation of employees and the success.
CIP- Continuous Improvement Process
CIP (Continuous Improvement Process) sums up all measures that are suitable for improving products, services, processes and individual activities within a company. The aim is to influence the mind-set of the employees: They should constantly check where and how they could improve their work. CIP focuses on many small measures that can be realised quickly, rather than one large, lengthier project.
CIP originates from series production in the automotive industry and was significantly shaped by Toyota and the so-called Toyota Production System. Since the beginning of the 1990s, it has become widely spread in companies with Lean Management and Kaizen. This is because a company and its employees can only be successful if both are constantly improving.
Important features of the improvement process
Characteristics of continuous improvement are:
- Asking each and every employee to contribute to improvement themselves
- The many different measures, which can be implemented quickly and bureaucratically on a day-to-day basis
- For the CIP there are no restriction in terms of the application area: products, services, processes, activities, technology, and workplace - everything can be improved.
- For the CIP there is no end – there is always something that can be improved
- It does not matter how the improvement is accomplished, what matters is the effect, not the method
- Important are principles such as Sorting, Avoidance, cleanliness, tidiness, order, simplicity, standardisation as well as setting rules and adhering to them
Advantages if the implementation
CIP enables companies to react flexibly and quickly to changed market- and customer demands and thus increase their competitiveness. Employees also benefit from a well-designed CIP Management. A complete and transparent organisational structure including clear responsibilities enables employees to discover and unfold their slumbering potential. Thereby they can become more involved in the processes of the company and, tat the same time identify more strongly with them.
Possible areas of application:
There are many processes and activities in a company where CIP can be used. The most important areas are administration and production.
1. In the office
The desk and the filings system should tidied in such a way, that only necessary items are present. These items are positioned in a dedicated area in a defined order. Employees then do not have to search for them, which speeds up processes and fewer mistakes are made.
2. In production and assembly
In the production and assembly departments of a company, it is crucial that employees do not have long distances to cover and that tools and work objects are within direct reach. This should ease the motion processes for the employees. In order to ensure no mistakes occur during processing, all the tools and all necessary information must be perfectly coordinated.
The further development of the corporate culture and good leadership are important success factors of the CIP. Dealing with these topics nevertheless does require a comprehensive commitment of the Change Management. However, if a company carries out such adjustments, it will be able to meet the demands of constantly changing market, customer and at times legal requirements.
Value Stream Mapping/ Design
The ongoing competitive situation requires of all companies a constant optimisation of the establishment of performance. Today, more than ever, the focus of lean management, the design of production systems and a supply chain is on the holistic optimisation of value streams across company boundaries. Value Stream Mapping is a simple technique for visualising the actual state in order to identify and analyse waste and potential for improvement in corporate processes. Based on this, the improved target state is then developed in the value stream design.
What is Value Stream Mapping?
Value Stream Mapping is used to note and visualize the actual state of the process in detail. It is important to analyse the entire process and not just individual sub-steps of the process. For this purpose, all important figures, data and facts from the production processes as well as the material and information flow are included. The recording is visualised by simple symbols.
What goals are meant to be achieved with the application?
Value Stream Mapping is about the analysis of material and information flows with the goals:
- Representation of material and information flow and their interrelationships.
- Identification of weak spots and waste in the value stream
- Simplification of the information flow and improvement of transparency
- Basis for operational communication and discussion
- Basis for a value stream design with implementation measures and fields of action
Rules when performing the Value Stream Mapping Method
- Use paper and pencil
- Team building by involving all parties concerned
- Consider, understand and evaluate on-site
- Check the data basis and, if in doubt, collect new data
Recording and conception of holistic value-producing processes:
- Representation of material flows
- Representation of information flows (order entry control)
- Representation always from ramp to ramp (call-off/delivery behaviour)
Use of few, standardized symbols to represent the flows and process chains:
- - Everyone who works with value stream has the same understanding of the symbolism
- - This understanding is the basis for target-oriented discussions
Use of current process data:
- Process time, setup time, Overall Equipment Effectiveness (OEE), number of employees, batch size/container size, inventories, number of product variants, working hours/shift models
Transparency on waste:
- - Waiting times between processes, resulting inventories or bottlenecks.
Calculation of lead times and value added times
Detection of causes for waste and derivation of necessary implementation measures
What is value stream design?
Value Stream Design (builds on Value Stream Mapping and is used to redesign production towards an efficient and customer-oriented value stream. The result is a lean factory or a lean service operation. As with the value stream mapping, a diagram with corresponding symbols is used to visualise the desired improved state.
Which goals are to be achieved with the application?
Value Stream Design is about the design of material and information flows with the goals:
- Optimisation of production processes
- Reduction of inventories, lead times (DLZ), transport effort, space requirements
- Simplification of information flow and improvement of transparency
- Reduction of the operational control effort
- Increasing delivery reliability and customer orientation by increasing flexibility and reaction speed
- Basis for operational communication and discussion
- Basis for implementation measures and fields of action
Whereas value stream mapping was concerned with recording the current state, value stream design is used to
- derive the target state by identifying waste in the current state while finding and outlining new lean solutions,
- implement the outlined target state by first breaking it down into sub-steps, naming deadlines, milestones and persons responsible and implementing the sub-steps, and
- verify the implementation of the target state, correct it if necessary and standardise.
TPM – Total Productive Maintenance
Economical production in Germany is usually only possible through sufficient automation of the production facilities. This compensates for possible cost disadvantages and maintains or even increases productivity and thus competitiveness. However, the advancing automation brings with it an increasing number of sources of disruption that counteract productivity. The widespread organizational separation of production and maintenance tasks also has a negative impact on the effective use of production equipment.
This can be remedied by the Total Productive Maintenance concept, which aims to ensure effective use of production equipment by transferring responsibility for routine maintenance tasks to production personnel. Care and interdisciplinary maintenance of plant and machinery can minimize downtime and improve effectiveness and availability.
The TPM philosophy is intended to help overcome functional separation with a view to greater process efficiency. The qualification of personnel in production and maintenance-related areas is of particular importance. The focus is on a common understanding of TPM and the alignment of goals with process and plant efficiency. The TPM goals are:
- Improving plant reliability by eliminating weak spots
- Minimization of life cycle costs of the plants
- Increased work safety
- Creation of a motivating workplace
- Effective use of personnel
- Minimization of sources of losses
TPM implementation - the approach
- Development of a TPM program with objectives, measures, milestones, deadlines, responsibilities and resources.
- Structuring of the plants, recording of their condition/defects with causes and consequences, derivation of measures.
- Definition of a pilot area, assignment of activities, training and instruction of plant operators, implementation of measures by gradual transfer of tasks to the plant operators, recording of results, development of work documents.
- Evaluation of the pilot experiences, perfection of work documents, extension of the employee competence up to autonomous maintenance.
- Implementation of the experiences, transfer to other areas.
- Processing of the experiences from the pilot areas into specifications sheets, procurement concepts for new plants.
SMED – Single Minute Exchange of Die
Due to the increasing number of variants and the growing demands for flexibility, fast setup in production is the crucial factor in being able to produce even small batch sizes economically. The SMED-Method can contribute to this. SMED stands for Single Minute Exchange of Die and is a method that deals with optimising the setup times of processes. When applying the SMED method, the setup time is reduced by both organisational and technical measures. Translated meaningfully, SMED means as much as: "Fast changeover under 10 minutes".
Using SMED, significant performance increases are achieved on the production lines. In addition, it is possible to switch much more frequently between different goods on one and the same line. This increases the flexibility of production and reduces the stock levels upstream and downstream of the aggregate. SMED also achieves an immediate restart of production with good parts. Significantly, fewer or no start-up losses have to be accepted.
What is the setup time and how does the setup process work?
If a machine or a production location, i.e. individual lines or entire lines, are set up for a special processing operation and equipped with the required tools, the duration of this changeover is referred to as the setup time. The setup time thus comprises the time span between the production of one part and the production of another on the same machine.
As a rule, the setup process consists of the following four steps:
1. Setup preparation
- Removal of the manufactured parts, deregistration of the old order
- Registration of the new order, provision of all required materials, parts, fixtures and information
2. Changeover of tools
- Removal of the previously required fixtures and tools
- Assembly of the fixtures and tools required for the next order
- Adjustment of tools and fixtures
- Adjustment of process parameters (pressure, feed, etc.)
4. Test and readjustment
- Production of test pieces
- Measurement and evaluation of results
- Correction of process parameters, retesting if necessary
Advantages of SMED
The SMED method combines the following advantages:
- Reduction of batch sizes
- Reduction of lead times
- Reduction of inventories
- Gain of capacities
- Facilitating of set-up processes
Just-in-Time (JIT) is a production strategy in which materials are delivered in exact quantities only when they are actually needed for production.
The Just-in-Time strategy aims to design the entire material flow in such a way, that it is timed to match the production process. Thus, the total process of value creation can become leaner. By reducing lead times, warehousing and capital tie-up, the economic success of a company can be increased.
The decision for JIT strengthens the competitiveness. Especially in markets where more and more substitutes are offered and individual companies can no longer distinguish themselves sufficiently by price or quality from their competitors, the internal value creation process is decisive. Due to low inventory levels, companies can respond more quickly to changing market- and customer needs. However, JIT requires a much closer cooperation between companies and suppliers and especially a detailed and smooth planning. Companies have to accept the risk of a greater dependency on suppliers and have to reckon with delivery failures in the event of bottlenecks.
Levelling / Heijunka
Fluctuations in demand are a cost factor that is sometimes unpredictable in companies, despite extensive empirical data. Within the framework of lean management, Heijunka has been developed as a useful method for smoothing the production flow and thus counteracting waste.
The Heijunka principle is an essential building block of the Toyota Production System, with the help of which the output quantity within production is to be smoothed to such an extent that fluctuations in demand remain ineffective for the process. Production experts also refer to this as levelling. This also prevents the bullwhip effect, in which even small fluctuations in demand in one process, cause ever-greater fluctuations in demand in processes upstream. In the worst case, this effect leads to material bottlenecks.
Advantages of Heijunka
- Ensuring a continuous supply to the market
- Ensuring a steady consumption of supplier parts
- Avoidance of peak loads on employees and machines
- Creation of transparency about incoming and outgoing goods
8 steps to production levelling
For the smoothing of production flow to be successful, good planning is required.
1. Identification of the pacing process
This is the main area in the value stream and therefore the basis for the associated steps.
2. Identification of the cycle time
This value indicates how long a work step takes at best to meet the customer's demand in a timely manner.
3. Checking the EPEI details (every part every interval)
This key figure can be used to describe the time interval that elapses before the same product can be produced again.
4. Definition of the level of levelling and the setup families
Efforts can be reduced by sensibly grouping similar products. This can shorten setup times and can improve the performance of the production system.
5. Division of capacities
Here the harmonization of production sections is aimed at, leading to the approximation of a more demand-oriented production.
6. Creation of the setup-optimal, smoothed target sequence
This value will be used as a reference in the future.
7. Planning of the Kanban number
Based on the optimal target value, the future target can be defined and target stock levels can be set.
8. Measurement of the sequence quality
Based on the values, the improvement process can now be driven forward and measures can be developed.