Lean Manufacturing
Lean Manufacturing Principles
The principles of Lean manufacturing and thinking, provide a method to specify and add "Value" while combating "waste", referred to as " Muda " (The Japanese word). Waste is the result of the over use of any resource required to produce a product or deliver a service. Waste is also identified as idle time where no value is being added to a product or service.
" It provides a way to specify value, line up value creating actions in the best possible sequence, conduct those activities without interruption whenever someone requests them, and perform them more and more effectively. In short, lean thinking is Lean because it provides a way to do more with less and less : Less Human effort, less equipment effort, less time and less space - while coming closure and closure to providing customers with exactly what they want " "Credit James P.Womack and Daniel T.Jomes LEAN THINKING"
Lean Manufacturing targets 7 main categories of waste:
-
Producing more than is required and building for stock causes waste. (Raw materials are used, resources have been used and it has no requirement or meet orders)
-
Waiting and Idle time adds no value to the products. (Products that are waiting in the production process have consumed material and add costs to the work in progress )
-
Handling material to many times. Delaying the movement of materials.
-
Inventory and stock. Due to waste in the production processes unnecessary raw material is required to be kept in stock, Work in Progress and finished goods
-
Motion - movement of equipment or people that add no value to the product .
-
Over-processing - unnecessary processing or procedures (work carried out on the product which adds no value) .
-
Defective equipment producing or reworking scrap.
The term “Lean” manufacturing was popularised by Womack and Jones in their book “The Machine that changed the world”. They have recently updated these thoughts in "Lean Thinking". The original book benched marked manufacturing companies around the world and found Japanese companies where far more efficient.
Before this a publication had been written on the Toyota
production systems which explained the principles of lean manufacturing.
Taiichi Ohno the author devised the original 7 categories by which companies
waste money. One of the most valuable tools of Lean Manufacturing Principles
is Value Stream Mapping.
There have many tools that help improve the 7 major losses which are summarised
below:
Overproduction
Companies suffering with quality problems will overproduce to ensure customer
orders can be satisfied This kind of issue can tackled using (Pokayoke)
and by understanding the machine process capabilities of the production
equipment. Six Sigma methodology combined
with Lean Manufacturing Principles and OEE Programs can drive benefits
here
If a company has to overproduce due to small orders and economics of batch
sizes optimising setup and change over times will help. SMED will help here
to. Reducing change overtimes will make smaller production runs more economical.
Waiting
Products and parts which are left standing around such as WIP or finished
goods is a major cause of waste, WIP is usually cause by producing large
batches rather than what is actually needed. Large batches are also produced
when the products are moved too many times as it seems easier to move them
in bulk. It would be better to remove the movement altogether.
Bottleneck machines will cause batching to go on. Using OEE and value stream mapping will identify and resolve this.
Transportation
The usual cause of excessive transportation is plant layout. In companies
that evolved over time products will have changed, but the layout of the
equipment may not have been considered or optimised. Using value stream
mapping tools will provide the information necessary to minimise transportation
Inventory
Many companies will over order to meet current demand due to waste in the
processes and the mistaken belief that ordering larger quantities will save
money. Having 20% of the ordered material standing around for months will
not save money but tie up cash in stock.
Kanban
system will drive production when and only when it is needed.
Motion
Good practices often reduces motion. Putting materials in set locations,
keeping a area tidy will remove the need to move parts and materials around
to simply make space for more. The best solution is to lay the plant out
to reduce motion and the distance travelled.
Over-processing
Rework is one of the biggest causes of over processing. By implementing
Six Sigma and OEE systems, waste caused by rework can be identified and
resolved. Poor setup of machine operations and their effectiveness will
extend cycle times and reduce output
Defective units
It may surprise you that when value stream mapping is carried out in many
organisations, 99% of the time the activities are adding no value to the
product.
The elimination of waste is the heart of Lean Manufacturing Principles. What is the value of removing 10% of your costs ? and the benefit. It will probably cost you very little to implement, you are simply removing activities that server no purpose and add no value.