What is a Muda?
Muda is a Japanese word meaning futility or uselessness
Two types of Muda
- Muda Type I: non value-adding, but necessary for end-customers. These are usually harder to eliminate because while classified as non-value adding, they may still be necessary. For example, while an end-customer might not view quality inspection in car assembly as value-adding, it is necessary to ensure the car meets safety standards.
- Muda Type II: non value-adding and unnecessary for end-customers. These contribute to waste, incur hidden costs, and should be eliminated.
Note that waste is any activity or steps in any process that doesn’t add value to the process or product.
Simply-
- Value adding steps (not wastes)
- Non-value adding steps (wastes)
3M: Wastes in Muda, Mura & Muri form (Japanese names)
Mura
MURA means overloading of an equipment, facility, or human resource beyond its capacity.
Consequences:
4D-downtime, defects, delays, and even disasters.
Mura could be eliminated with-
- Work Standardization
- Work flow or logical directions to be taken
- Taking care of Takt time during manufacturing/services (rate at which a finished product needs to be completed/arrived in order to meet customer demand
Muri
In lean manufacturing concept ‘MURI’ refers to unevenness in production volume.
Consequnces
Muri may cause overload in one time and idleness in other time
Muri could be eliminated with:
Implementation of heijunka or production levelling.
- Waste of non-utilized Talents
- Over-production muda
Producing more than or faster than what is needed
Causes
- volume incentives (sales, pay, purchasing)
- high capacity equipment
- line imbalance; poor scheduling/shifting
- poor production planning
- cost accounting practices that encourage build up of inventory
- Over processing muda
Non-value added man processing or non-value added machine processing
Causes
- unclear customer specifications
- frequent engineering changes
- excessive quality (refinements)
- inadequate value analysis/value engineering
- unclear work instructions
- Transport muda
This type of waste involves unnecessary material movement or unnecessary tools or equipment movement
Causes
- poor route planning
- distant suppliers
- complex material flows
- poor layout
- disorganized workplace
- line imbalance
- Time muda
This is the ideal or waiting time of man or machine
Causes
- unsynchronized processes; line imbalance
- inflexible work force
- over-staffing
- unscheuled machine downtime
- long set-up
- material shortage or delay
- manpower shortage or delay
- Inventory muda
This involves excessive process (WIP) inventories
Causes
- over-production
- imbalanced line
- big batch sizes
- long lead times
- local optimization (turf mentality)
- large minimum order quantities
- high rework rate
- JIT-incapable suppliers
- lack of material requisition and issuance standards
- Motion muda
Unnecessary movement and motions of worker is also an important source of waste
Causes
- poor lay-out and housekeeping
- disorganized work place and storage locations
- unclear, non-standardized work instructions
- unclear process and materials flow
- Defects muda
This involves processing due to the production, rework or repair of defects or materials used due to defect and rework
Causes
- unclear customer specifications
- incapable processes
- lack of process control
- unskilled personnel
- departmental rather than total quality
- incapable suppliers
- Non-Utilized Talent – Employees that are not effectively engaged in the process.
How we deal with them?
- Implement work standardization and job description and mock up training initially before a person is busy in his/her job.
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