The 3M of Lean – MUDA, MURA & MURI (2024)

Hey folks, today our experts have brought an interesting topic for you. This concept forms the base of Lean Methodology. It’s widely used in all industries round the globe to identify and reduce waste.

The Toyota Production System, which is known as the precursor to the Lean Methodology, is based on the philosophy of achieving the complete elimination of all waste in pursuit of the most efficient methods. These wastes are categorized In 3 main sections, namely Muda (Waste), Mura (Inconsistency), Muri (Over-burdening).

MUDA

Muda means wastefulness. There are 2 types of Muda, Type-1 which can be referred as ‘Value enabling activities’ and Type-2 which are the ‘Non value added activities’. Our aim is to eliminate this Type-2 Muda and minimize Type-1 Muda.

There are 8 categories in this Type-2 Muda which are abbreviated as DOWNTIME. We will see each category in detail specifying their definitions, causes and tools used to eliminate them.

• D – Defects

Defects are caused when the product does not meet costumer specification resulting in rework or scrapping the product. These activities add unwanted cost which does not provide value to the costumer.

The main causes could be incapable processes, lack of process control or standardization, unskilled labor or faulty design of process.

We can overcome these problems by implementing methods like Poka-yoke and work standardization for consistent defect free product.

• O – Overproduction

Overproduction is caused when a product is being manufactured in excess of its demand (Push system) or producing at a faster rate than needed. These practices cause problems like higher storage costs, more capital expenditure to manufacture and decreased quality.

The causes of overproduction are volume incentives, high capacity equipment, line imbalance and poor production planning.

We can overcome these problems by implementing methods like SMED to reduce set-up time to enable small batch production, Kanban system to facilitate pull production and adapting Just in time philosophy.

• W – Waiting time

Waiting time or idle time for Man Machine and Material all come under this. This causes uneven production.

The causes are mainly line imbalance, unplanned machine downtime, long set-up times, material shortage or delay and manpower shortage or delay.

We can overcome these problems by using time study, line balancing, develop multi skilled labor and redesign process for even production flow.

• N – Non-used talent

This was not the part of the original Toyota Production System .It attributes to the unused knowledge and skills of operators working in the factory.

This waste can be seen when employees are poorly trained, employees are not challenged to come up with ideas to improve the work, ineffective communication.We can overcome these problems by leadership and training among employees and kaizen events

• T – Transport

This is caused by unnecessary material, tool and equipment movement.Excess moving not only costs money but also increases risk of product being damaged, lost or misused.

The causes could be identified as poor route planning, distant suppliers, poor layout and line imbalance.We can overcome these problems by using tools like Spaghetti diagram and implementing “U” shape production layout.

• I – Inventory

This waste is caused when companies are having more inventory than what is necessary for steady flow of work; these include both raw material as well as WIP inventory. This causes capital loss as well as the problems are being hidden away in inventory.

The root causes of this problem are over-production, over-purchasing, high rework rate, imbalanced lines, longer lead times, JIT- incapable suppliers.We can overcome these problems by implementing Kanban system and one piece flow and we can also try to reduce the current buffer inventory present between production stages.

• M – Motion

Motion waste includes the unnecessary movements of worker or machine and is considered as non value added activities. Wasted motion increases wear and tear of both man and machine and also increases risk of injuries.

The causes could be poor layout, disorganized work place and undefined material flow.We can overcome these problems by implementing 6S at the workplace, ergonomic workplace design and using spaghetti diagrams to design efficient work flow.

• E – Excess processing

Excess processing waste refers to doing more work having more processes and components than what is necessary by the costumer. This can also happen if we use machine equipment of higher capacity and precession than what is required.

The caused could be associated which unclear costumer specification, frequent engineering changes, excessive quality.We can reduce this waste by implementing process map and having a clear idea of customer requirements.

MURA

Mura means ‘Variation’ or ‘Unevenness’ and it is the key reason for the existence of any of the 8 waste that we just saw. In simpler terms Mura leads to Muda. Mainly Mura could be seen as variation in ‘Customer demand’ or variation in ‘Process’. Variation in demand in usually caused by inefficient information flow from customer to manufacturer otherwise known as the bullwhip effect. Whereas variation in process occurs when capacity of workstations vary across the production process causing waste like overproduction, inventory etc.

Using practices like product leveling or Heijunka will help us solve the problem of unwanted variation in the production process and will allow us to processing orders according to customer demand. Other practices like creating a modular product design and single piece flow will also help us reduce unevenness.

Muri means ‘Overburdening’. It could occur when machine or man is being used for more than 100% of its capacity to complete a task, which could lead to break down of machines or fatigue in manpower. This results in decrease in productivity and efficiency.

We could try and eliminate Muri by standardizing your process, practicing Jidoka and analyze the root cause of the problems. Preventive Maintenance and Autonomous Maintenance will also help with machine related Muri.

That’s all for today , hope you enjoyed it, Kindly share your views/feedback so that we can help you by adding more value in the upcoming articles.