8 wastes of LEAN manufacturing

Reducing 8 wastes of LEAN by Industry 4.0

The 8 wastes of LEAN – what are they ?

To understand the 8 wastes of LEAN, it is necessary to first understand what LEAN is. LEAN is a philosophy of work that focuses on the removal of waste within a process. The central principle is that the customer (the consumer of the end-product of the process) is only willing to pay for parts of the process that are value-adding, and is not willing to pay for parts that are not value-adding. In the manufacturing process, the use of resources for any goal other than the creation of value for the end customer is wasteful and must be avoided. Non-value adding activities or resources are Waste, or Muda in Japanese.

8 wastes of lean manufacturing that must be eliminated from the shop floor

Example: if you are a job shop machining castings and supplying them to a customer, the customer is paying for machined castings with metallurgical quality and final machined dimensions matching his specifications. Anything directly contributing to this is value-adding, which is all processes directly involved in making the castings in your foundry and machining them. Non-value adding costs could be these:

  1. Machine breakdowns
  2. Spending money on cutting to 10 microns tolerance when the drawing specifies 20 microns
  3. Raw material, machining and indirect costs of rejected parts
  4. Getting castings with more raw material than necessary, and spending more time on machining.

Non-value adding costs are Waste, or Muda, and must be eliminated. LEAN, in short, is Making more with less.

The 8 wastes of LEAN – explained

The 8 wastes of LEAN, in brief

The original 7 wastes of LEAN (Muda) were developed as part of the Toyota Production System (TPS). The seven wastes of LEAN are Transportation, Inventory, Motion, Waiting, Overproduction, Overprocessing and Defects. This later became the 8 wastes of LEAN with the addition of non-utilized talent or skills when the Toyota Production System was adopted outside Japan.

1. Transportation – Transporting products, tools, equipment or people further than necessary.
Why is this a problem ? Movement leads to damage and defects, and these cost money. Also,  unnecessary movement of equipment and people leads to more work, greater wear and tear, and exhaustion.
What is the solution ? Well designed factory layout, no over-production (and resultant necessity of moving parts to inventory holding areas), proper scheduling.

2. Inventory – Material that is that is sitting idle and not being processed or given to the customer.
Why is this a problem ? Raw material, work in process or finished goods all cost money. Inventory means capital that is locked up, unusable elsewhere, for which you are paying interest. Inventory also needs space, unnecessary transportation, and damage during storage.
What is the solution ? Buy raw material Just in Time and produce Just in Time; reduce buffers between production processes; make schedules more predictable by reducing breakdowns, reduce rejections.

3. Motion – People or equipment making unnecessary motions in a process due to workspace layout, ergonomic issues or searching for items.
Why is this a problem ? It increases the process time, increases human fatigue, equipment wear and tear.
What is the solution ? Ensure that the workspace is well organized, tools can be reached quickly without searching for them, place equipment near the production location, keep materials at an ergonomic position to reduce stretching and straining.

4. Waiting – Machine waiting because there is no raw material and it is waiting for the previous step in the process to complete, or people waiting because machines have broken down.
Why is this a problem ? Waiting is downtime. You are paying for a machine and its operator even while it is waiting.
What is the solution ? Knowledge of actual cycle times, knowledge of downtime incidences caused due to waiting for a previous process being slower or material handling being poor, better material handling, better balancing of machine capacity in related processes, more workforce, fewer breakdowns.

5. Overproduction – Producing a higher quantity of the product than necessary for the immediate requirement.
Why is this a problem ? This results in finished goods inventory. Making unnecessarily more of one part means you are making less of another necessary part. Inventory costs money – there is money locked up in the parts, and you are paying interest on it. You need space for storage, and you need to store the parts carefully without getting damaged – both these cost money.
What is the solution ? Just-in-time manufacturing, better scheduling, better adherence to schedules, improving predictability of machines through preventive maintenance.

6. Overprocessing – Performing any activity or providing features that are more than necessary for the product. Like providing more hardness, a closer tolerance, thicker coat of paint or better surface finish than necessary,
Why is this a problem ? Extra processing involves a longer processing time, costlier equipment, more material or more processes. All these are a waste. E.g., on a CNC lathe, better surface finish would mean lower feedrate and hence higher cycle time. Closer tolerance would mean a more expensive machine and more frequent tool changes and higher tool cost.
What is the solution ? Understand the customer’s exact drawing requirements and the end function of the part, and produce to the required specifications.

7. Defects – Products that do not match the specifications, and are rejected or have to be reworked.
Why is this a problem ? A rejected part results in waste of the cost of raw material and processing up to the point at which it was rejected. A reworked part involves additional cost of reworking.
What is the solution ? Improve operator training, inspection systems, machine capability through better preventive maintenance.

8. Non-utilized talent – Employees that are not effectively utilized. This is the eighth waste, not part of of the original 7 wastes of TPS.
Why is this a problem ? People cost money, and not using someone’s skills effectively is an opportunity cost. Using a higher skilled person for a lower skill job is a waste of money, because you are paying for the higher skills but not using them. People actually doing the work know the inefficiencies in processes, and if you do not use this knowledge you are under-utilizing them.
What is the solution ? Understand people’s capabilities, use their skills and knowledge fully, reward them for performance.

How does Industry 4.0 help to reduce the 8 wastes of LEAN ?
To reduce waste or muda, you need to know where it is occurring, and how much is occurring. For this you need a good system of acquiring information and reporting. This is what Industry 4.0 does. It is about getting data directly from processes and machines, accurately and instantly. Machine monitoring and process monitoring is done 24/7, automatically. Wastes like machine downtimes, part rejections, extra processing can be identified, their quantum determined, and action taken to reduce or eliminate them.


A memorial to a sparrow

I was in Ahmedabad, in Dhal ni Pol, part of the beautiful old walled city (that’s a UNESCO world heritage city), and saw this memorial to a sparrow. It is a stone plaque on the wall of a house. The top half mentions the incident, date and time at which the sparrow died. The bottom half has a bas-relief with the sparrow and creepers around it. I thought it remarkable that someone actually saw a bird fall to a bullet and was moved enough by it to remember it in stone forever.

Not surprising though, for a city that loves its birds and takes special care of them through beautiful chabutros, or bird feeders. They are raised structures to keep the birds safe from cats and dogs, and have a platform at the bottom for people to sit.

You’ll find these dotted all over the old city. So people hang around at the bottom while birds hang around at the top, and cats too hang around at the bottom looking up and salivating. People living around a chabutro refill it with grain and water every day. A lovely tradition that’s been around for 150-odd years.

About his blog from LEANworx: Plug-and-play Industry 4.0 system for MSMEs.

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