The 3 M's of the Toyota system
The Toyota Production System targets three types of loss, not just one. Most companies only know the first.
Muda — Waste
Activities that consume resources without adding value. These are the classic 8 wastes.
Mura — Unevenness
Inconsistency in workflow or demand, which creates load spikes and troughs.
Muri — Overburden
Demanding more from people or machines than they can reasonably handle, whether from demand spikes or poor ergonomics.
Unevenness creates overburden, and overburden creates waste — the three are always connected.
How one causes the other
The three M's form a chain: Mura (irregular demand) forces periods of Muri (overloading people and machines to meet spikes), which causes mistakes, breakdowns, and rework — in other words, Muda. Leveling production with Heijunka is precisely how you attack Mura before it turns into the other two.
Why attacking only Muda isn't enough
A Lean program that only cuts waste, without leveling demand or respecting people's real capacity, tends to recreate the same problem a few months later. All three M's need to be attacked together for the gains to hold.
About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.