The fundamental principle of lean manufacture is
eliminating waste from the manufacturing process Taiichi Ohno was a Japanese industrial
engineer and business man who used three Japanese words to describe waste; Mura, Muri and Muda. Mura is unevenness, Muri is
overburden or unreasonable demands and Muda is the non-value adding actions
within processes (Liker, 2004).
customers want high quality products that are delivered on time and at the
right price. By eliminating waste in production processes, high-quality
products can be achieved (Krafcik, 1988).
Muri underlies Muda and Mura, the causes
of Muri (overburden) include:
on processes that you’re not trained in
laid out work environments
of proper tools and equipment/ unreliable equipment
The company’s profit is the selling price minus the
costs associated with making the product. The selling price is very much
dictated by the market, if the company charges too much then customers will
seek the product elsewhere, and sometimes if you charge too little there is
potential to lose out on customers as they may perceive that the product is of
low standard (Ohno, 1988).
Therefore, we only improve profits by reducing
costs; this means the removal of waste from all processes.
Mura, Muri and Muda
‘wastes’ were categorised into seven areas;
Overproduction; Over producing product beyond what the
customer has ordered.
Inventory; the work in progress (WIP) and stocks of
finished goods and raw materials that a company holds.
Waiting; the act of waiting for a machine to finish,
for product to arrive, or any other cause.
Motion; the physical movement of a person or machine
whilst conducting an operation.
Transport; the movement of product between operations,
Reworks/Defects; product rejects and rework within your processes.
Over-processing; conducting operations beyond those that customer