Muda, Mura and Muri
Within the Lean Manufacturing environment, there are three types of deviation from the optimal allocation of resources, these are ‘Muda’ (waste), ‘Mura’ (irregularity or un-evenness) and ‘Muri’ (unreasonable, unattainable or overburden). The little cartoon below illustrates these three ‘labor related’ concepts.
Muda Mura Muri
The Japanese word ‘Muda’ means ‘futility, uselessness, idleness, wastefulness and waste’. Within the Lean Manufacturing environment, Muda resolution involves improvement programs aimed at reducing waste within the production process. There are seven types of Muda (waste) within the manufacturing environment:
1) Transportation – moving products in ways that are not actually required to perform the processing. Each time components or products are moved, they are placed ‘at risk’, and also incur the cost of such transportation (even within the manufacturing facility: manpower, time, moving equipment, etc.).
Results from (to):
- Unnecessary movement of parts between processes
- Complex material flow paths
- Improper or failed process close/finish
- Wasted or disorganized floor space
- Unnecessary material handling
- Potential damage to products
- One of the major sources of manufacturing injury involves the transportation of raw materials, or finished goods within the production environment.
2) Inventory – all components, work in process, and finished products not being processed. If inventory isn’t increasing value, it is waste; consuming valuable resources like ‘working capital’ and ‘storage space’ (contributing to overhead).
- Excess inventory based on bad inventory data, such as an improperly configured or managed MRP, diverts limited capital into creation and maintenance of waste. Excess inventory results in consuming valuable storage space to hold unnecessary goods.
- A scarcity of items, on the other hand, results in stock outs, expediting, or lost orders.
- After taking a thorough inventory and considering all the money you could have saved if you had not purchased the things you don’t need and don’t regularly use. Keep those thoughts burned into your memory so that you will be less likely to make the same mistake inventory acquisition mistakes in the future.
3) Motion – people and/or equipment moving or walking more than is required to perform the process. Motion refers to people and equipment rather than ‘materials or products’. People moving from here to there to perform some specific task consumes production time that could be used in revenue generation, it also contributes to fatigue and potential injuries. Having to relocate equipment risk that equipment to potential damage, and extra wear and tear.
- Inadequate standard operating procedures
- Poor maintenance, stocking or stock delivery
- Badly designed or configured work centers
- Inadequate training
4) Waiting – waiting (inactivity) for the next production step. Whenever manufacturing is not actually in process at any one (or more) stages of production, whether it be due to workers waiting on parts, or due to some bottleneck impacting the production/assembly process, the manufacturing facility is losing money that should be driving actual revenue-based production. Far too much time is spent ‘waiting’ in today’s manufacturing sector.
Studies of waiting within the manufacturing and production sector consistently find that the major causes of waiting are associated with:
- Inconsistent work methods (lack of process standardization),
- Unscheduled system Interruptions,
- Lack of process standardization (too many ‘on-the-fly changes’),
- Capacity doesn’t match volume (inadequacies of facility, manpower, resources or workflow),
- Excessive Complexity (why do it with ‘one part that works’ when you can use a dozen we have to put together’)
- and Training inadequacy (what do you mean he has never run a robot welder before?)
5) Over-processing – resulting from poor tool or product design creating activity. When work is performed in relationship to production that simply does not need to be done, it is wasteful. Further such ‘extra work’ compromises the production schedule in such way as to delay or reduce work that needs to be accomplished. It may result in waiting at other production phases downstream from the area of ‘over-processing’.
- Out of date standards
- Attitude - ‘Always done it like this’
- Lack of understanding of the process
- Lack of innovation & improvement
- Inadequate standard operation procedures
6) Over-producing – production ahead of demand. When more product is being produced than is required to meet customer demand a wasteful state of over-production exists. Over-production is the worst form of ‘muda’ because it contributes to, and may in fact ‘hide’ other forms of waste.
- To produce sooner, faster or in greater quantities than the absolute customer demand
- Manufacturing too much, too early or “Just in Case”
- Overproduction discourages a smooth flow of goods or services
- Takes the focus away from what the customer really wants
- Leads to excessive inventory
7) Defects – time and efforts involved in inspecting for and fixing defects. Anytime (every time) defects occur, extra costs are incurred including the cost associated with repair, re-work, or replacement. In some manufacturing environments it is not uncommon for defects to be attributable for 50 to 100% of cost overruns.
Next time, we will look more closely at ‘Mura’ and ‘Muri’ and how they impact our Lean Manufacturing environment.