What are the 8 lean tools

Lean Manufacturing

In lean manufacturing, “waste” is defined as anything that doesn’t add value to a product. “Value” in manufacturing is defined as anything that a customer would be willing to pay for.

So, waste is any cost incurred in a process that does not benefit the customer. Lean manufacturing is centered around eliminating waste from manufacturing processes.

Lean practitioners commonly agree on 7 wastes (or muda, as they are referred to in the Toyota Production System):

Transport
Inventory
Motion
Waiting
Overproduction
Overprocessing
Defects

These wastes were defined by Taiichi Ohno, father of the TPS. Some practitioners include an 8th waste, unutilized talent. While the first 7 wastes are directly related to manufacturing processes, the waste of unutilized talent is specific to manufacturing management.

Transport waste is defined as any material movement that doesn’t directly support immediate production. An improper facility layout, poor production planning, poor scheduling can generate transport waste. Another example is poor workplace organization, which results, in unnecessary additional material transport.

Inventory waste refers to any supply in excess of process requirements necessary to produce goods or services in a Just-in-Time manner. Causes of inventory waste include inaccurate forecasting systems, inefficient processes or suppliers, long changeover times, unbalanced production processes, or poor inventory management and tracking.

Motion waste is defined as any movement of people that doesn’t contribute added value to the product. Examples include moving equipment, reaching or bending, or gathering tools more than necessary, as well as unnecessarily complicated procedures. Motion waste is often caused by ineffective plant layouts, lack of visual controls, poor process documentation, or poor workplace organization.

The waiting waste refers to as any idle time that occurs when codependent events aren’t fully synchronized. Examples of this waste include idle operators waiting for equipment, production bottlenecks, production waiting for operators, and unplanned equipment downtime. Waiting can be caused by inconsistent work methods, lack of proper equipment or materials, long setup times, low man/machine effectiveness, poor equipment maintenance, or skills monopolies.

Overproduction is defined as producing more than is needed, faster than needed, or before it’s needed. This form of waste is most commonly seen in a "push system" supply chain. Automation in the wrong places, lack of communication, local optimization, low uptimes, poor planning, and a just-in-case reward system can cause overproduction waste.

Over-processing refers to any redundant effort in production or communication that does not add value to a product or service. Over-processing waste includes endless product or process refinement, excessive information, process bottlenecks, redundant reviews and approvals, and unclear customer specifications. It is caused by decision-making at inappropriate levels, inefficient policies and procedures, lack of customer input concerning requirements, poor configuration control, and spurious quality standards.

Defect waste is defined as the loss of value do to the scrap, repair, or rework of a product that deviates from specifications. Excessive variation in production processes, high inventory levels, inadequate tools or equipment, incompatible processes, insufficient training, or transport damage due to poor layouts and unnecessary handling can all lead to quality defect waste.

The waste of unutilized talent refers to underutilizing or engaging employees in a process. This could take the form of employees performing unnecessary work when their talent could be utilized in activities that add greater value, or not utilizing employees’ critical thinking abilities and feedback in processes. Unutilized talent also includes allowing employees to work in silos, which prevents them from sharing their knowledge.

Eliminating the 8 wastes from a manufacturing value stream is the core of lean manufacturing. Lean manufacturers should focus on building processes that make these wastes obvious so that they can be addressed—and improvements can be made—immediately.

There are many tools and techniques within lean manufacturing that aim to reduce and eliminate waste. Check out our guides to kaizen and gemba walks to learn more about some of these techniques.

Lean manufacturing, often known as ‘Lean’, is a methodology focused on the minimisation of waste along the value stream of any manufacturing workflow. Lean manufacturing emphasises on optimising quality, time, cost and resources during production. Any processes in the value stream which fail to value-add to the workflow are eradicated.

First introduced in the 1990s, ‘Lean’ continues to impact manufacturers around in world in any industries, be it pharmaceutical, food and beverage or automobiles and more.

The following are the 8 most commonly used lean manufacturing tools which you should know. When deciding which tool to use, remember:

“Some tools require more effort than others and organisations should start with the simplest tool to solve their problems”

1. Jidoka

Also referred to as ‘autonomation’ Jidoka is a lean manufacturing tool that infuses automation with human intelligence. Manufacturing equipment are programmed to be able to differentiate between the ‘good’ and ‘bad’ throughputs without having the operators to do so manually. This translates to higher productivity gains and lower labour costs because each operator can be freed up to manage multiple machines (also known as multiprocess handling). In a production plant that uses Jidoka, anyone can pause the workflow whenever a problem is observed to harm the quality of the outputs.

Jidoka uses these 4 steps to ensure than an organisation delivers defect-free products:

Discover an abnormality
Stop the process
Fix the immediate problem
Investigate and solve the root cause

By eradicating the root cause of defects, Jidoka is useful as a tool to ensure continuous improvements in your production flow.

2. Just-in-time

Speed to market and costs of production often differentiates a ‘good’ manufacturer from a ‘bad’ one.

“Just-in-time (JIT) manufacturing is a methodology used by manufacturers to ‘make only what is needed, when it is needed, and in the amount needed.”

By coordinating raw-material orders from suppliers with production schedules, manufacturers can effectively reduce inventory costs and wastes by receiving inputs only when they are needed for production. Manufacturers also stand to benefit from higher cash flow and lower space requirements.

One note of caution: JIT manufacturers have to be able to forecast their demand accurately.

3. Plan, Do, Check, Act (PDCA) cycle

PDCA cycle is a continuous improvement approach to iteratively improve products, people, and services. Not limited to manufacturers, it involves testing of solutions, analysing of results and improving the processes.

Plan: Identifying and analysing the problem. Develop hypotheses about the problem.
Do: Implementing the plan and measuring the results
Check: Verify results against expected results to determine effectiveness. Decide if the hypothesis is accepted for debunked
Act: If solutions were successful, implement it. Iteratively go through the entire process again to keep improving

For those familiar with the Scientific Enquiry Method, PDCA is similar to it in terms of:

Plan (developing a hypothesis)
Do (running experiments)
Check (evaluating results)
Act (refining experiment and trying again)

4. 5S

5S is a philosophy of organising and managing the workspace through the elimination of the 8 wastes defined in the lean manufacturing system. The 8 wastes are:

Defects
Overproduction
Waiting
Non-Utilised Talent
Transportation
Inventory
Motion &
Extra-Processing

The 5S stands for:

Seiri – Sort
Seiton – Set in Order
Seiso – Shine
Seiketsu – Standardise
Shitsuke – Sustain

Simply put, the 5S aims to

Remove items which are no longer needed from the production floor (sort)
Organise items, equipment in the production floor to optimize efficiency and flow (straighten)
Performing regular maintenance on equipment and machinery and planning for maintenance to mitigate the occurrence of breakdowns and stoppages (shine)
Implementing a standard operating procedure (SOP) to ensure that the aforementioned is imbued into each operator and there are schedules and instructions in place to assign the tasks fairly and effectively (standardise)
Keeping both the production floor and management in the organisation involved. Production managers, as well as other executives, should put in the effort to ensure that 5S is a continuous long-term program rather than an one-off event. project. 5S should permeate as part of the organisational culture (sustain).

5. Six sigma

Six Sigma is a technique used to improve productivity and performing by reducing the likelihood of error. It is a data-driven approach and applies statistical methodology to minimise defects. It is also known to help manufacturers reduce the changeover time from one process to another, reduce the cost of production and increase the satisfaction level of clients.

Six Sigma is characterised by DMAIC – Design, Measure, Analyse, Improve, Control

1. Define

The production floor works with the management to determine the shared goals and the resources that are required. For example, reducing defective goods of ABC production line by 20%.

2. Measure

Measure is about choosing the suitable metrics and tools to quantify and measure the effectiveness of the plan. It involves:

Quantifying the problem and presenting supporting data
Determining the yardstick for performance. Could it be yield, manufacturing cycle time or OEE? Organisations can refer to an industry baseline to benchmark to.

3. Analyse

The stakeholders would analyse the production floor and its various product lines and identify ways to minimise defects. Statistical tools and analysis are often used to determine the source of the problems.

4. Improving

The stakeholders find out the constraints and factors that affect productivity. It often involves hypothesis testing to find out if ‘A’ affects ‘B’ in the process flow

During this step, project teams seek optimal solutions, then develop and test the plan of action for improving a process or goal.

5. Control

As the final step in six sigma, ‘Control’ refers to the determining if the stated business goals and objectives were achieved and whether the improvements are sustainable.

6. Heijunka (Level Scheduling)

Implementing Heijunka would help manufacturers react to fluctuations in demand and utilise their capacity as well as possible. Heijunka relies on scheduling and production based on customer order and demand, rather than work batches. This brings about the benefits of lower inventory costs (similar to that of JIT) because the organisation manages its inventory level based on order volume.

The 2 ways of scheduling and levelling production are:

1. Levelling by volume

Scheduling your production by the average volume of orders received. This is especially useful for manufacturers with uneven daily demand (e.g. Mon – 3 orders, Tues – 10 orders, Wed – 7 orders etc.). By scheduling the production using the average volume of orders received, manufacturers can have a stable flow of work, 5 days a week to meet the week’s demand.

2. Levelling by type

This is useful for manufacturers who produce a variety of products. It focuses on scheduling production based on the average demand for each product in the overall product portfolio.

7. Overall Equipment Effectiveness (OEE)
The OEE score is calculated by the following formula:

OEE = Availability x Performance x Quality

It is a measure of manufacturing productivity for a piece of production equipment, or an entire production line. Measuring OEE provides important insights on production losses and potential areas for improvement.

8. Total Productive Maintenance (TPM)

TPM focuses on reducing the machine downtime of each production line by increasing the reliability of the equipment used during production.

The 3 key components of TPM are:

1. Preventive Maintenance

Preventive Maintenance refers to scheduled maintenance work which is performed on a thorough and periodic basis. The maintenance crew is assigned to check all the equipment for anomalies or problems. This mitigates the chances of sudden breakdowns during normal operations or when the throughputs are suddenly increased.

2. Corrective Maintenance

Corrective maintenance examines the equipment which often breakdown, to analyse the areas needed to be fixed, as well as to determine if there is an imminent need to invest in new physical assets to replace them.

3. Maintenance Prevention

As the name suggests, maintenance prevention involves proper evaluation to ensure that the equipment purchased are suitable, as well as a good fit for the production line. Poorly-purchased equipment may not only expense many resources to maintain, but they may also cause bottlenecks along the production line. This would equate to a loss of investment and productivity for the production facility.

Lean Manufacturing is an important way of management within the production/manufacturing world whose concepts have slowly and steadily entered into the world of business and has proved to be beneficial in all strata of these businesses. Using Lean Manufacturing is all about understanding the concepts behind these tools and techniques. Once you’re familiar with these concepts, implementation can be based on your work culture and production style, as Lean Manufacturing has managed to strike success in all different sectors and forms of businesses.

Selection of the correct lean manufacturing tool to implement in your production facility is not a trivial task. You should take into consideration your organisational culture, production schedules and industry. As mentioned at the beginning, it may be worthwhile to first start with the simplest tool to boost productivity.