Muda, Muri and Mura

farhanWhen you ask a number of people to explain Lean Manufacturing in one sentence, most of them will answer: “eliminate waste”. The reason is that eliminating waste or Muda is a relatively easy way of indentifying the low hanging fruits for improvement in an organization. However, Muda is not the only ‘M’ Toyota has built its famous Toyota Production System around, there are two more: Muri (Overburden) and Mura (Variation).

Muda (無駄) is a general Japanese term for an activity that is wasteful or is unproductive, etymologically or un-useful (駄) in practice or others. A process consumes resources and adds value by producing goods or providing a service that a customer is willing to pay for. However, waste occurs when more resources are consumed than are necessary to produce the goods or provide the service that the customer actually wants. The main causes of these time and resource wasting activities are mostly: lack of communication, inefficient resources or not understanding the requirements of the customer specs. This means, if a process is to be effective, then every activity must be properly documented; communication must be adequate; and customers’ need must be understood as much as possible.

Muri (無理, “unreasonable”) is a Japanese term for overburden, unreasonableness or absurdity. It is based on the belief that “excessive strains put on the development processes and teams are most likely to result in unrealistic outcomes with limited time”. When a situation such as this arises, it is most likely due to inadequate skills, poor planning, under estimation and poor task schedules. So, how can these types of events are avoided during production? The answer is simple: plan the manufacturing process well; prioritize activities, understand the process variables such as time, resources, and skill levels of workers; ensure estimation is done correctly, etc. Identifying the balance between not enough work and too much work is a delicate and difficult point to achieve, but becomes one of the hallmarks of the Toyota Way.

Mura (斑 or ムラ)[ is a traditional Japanese term for unevenness, inconsistency in physical matter or human spiritual condition. Unevenness can be found in fluctuation of customer demand, process times per product or variation of cycle times for different operators. Mura is avoided through Just In Time system which is based on little or no inventory, by supplying the production process with the right part, at the right time, in the right amount, and first-in, first out component flow. Just in Time create a “pull system” in which each sub-process withdraws its needs from the preceding sub-processes, and ultimately from an outside supplier. When a preceding process does not receive a request or withdrawal it does not make more parts. This type of system is designed to maximize efficiency by minimizing storage overhead.

Asprova has been instrumental in improving productivity by ensuring existence of only value adding activities in the supply chain. Our advanced planning and scheduling features assist manufacturing companies to identify the best way of doing the job through the removal of unnecessary financing costs, worthless inventory and overworked employees, thereby establishing a smooth flow of standardized work.

 

Seven Types of Waste

Flickr © Graham Hellewell

Taiichi Ohno, the architect of the Toyota Production System developed the concept of ‘MUDA’ (無駄) or ‘’Waste’  is applicable equally to both manufacturing and the service sector of the economy. These seven wastes are described below:

Over-Production: This usually happens because of working with oversize batches, long lead times and poor supplier relations. The key element of  JIT is making only the quantity required of any component or product. Sound stock management procedures and production techniques are necessary to ensure that the correct quantities are ordered and made.

(Read also Just In Time Schedule)

Excessive Inventory: Unwanted inventory costs you money – besides, it needs space and packaging. It can also get damaged during transportation and become obsolete. Every piece of product tied up in work in progress or finished goods have a cost and until it is sold that cost have to be borne. So the objective is to carry as little as possible to meet the requirements (see here how one company reduced finished goods inventory by 62.8%).

Waiting Time: Machines that are not compatible and produce at different rates can cause waiting on the production line. So processes become ineffective and add no value – only cost and inconvenience. Instead, the flow of operations should be smooth and continuous. Asprova supports eliminating unnecessary waiting time between processes by synchronizing multiple processes in the schedule.

Unnecessary Motions: It concerns the design of movement within the working environment as resources are wasted when workers have to end, reach or walk distances to do their jobs. It is vital to make sure that every movement is minimized while still performing the required task. So workplace ergonomics assessment should be conducted to design a more efficient environment.

Redundant Transportation: Moving a product between manufacturing processes adds no value, is expensive and can cause damage or product deterioration. So loads should be maximized; goods should be transported to the correct location and not require additional transportation.

Defects: Products should be designed so as to build in quality from the outset through good use of materials and processes. Defects require an organization to instigate post-manufacturing inspection processes with consequent costs and may involve re-working of an item or failure to meet customer service requirements.

In-appropriate Processing: A basic principle of the TPS is doing only what is appropriate. Improper techniques, oversize equipment, working to tolerances that are too tight, perform processes that are not required by the customer’s costs time and money. Hence overly elaborate and expensive equipment is wasteful if simpler machinery could do the job.

Asprova has always strive to go an extra mile by collaborating with their clients to eliminate overproduction and reduce stock-holdings, while minimizing stock-outs.

 

 

Photo Credit: Flickr ©Graham Hellewell