In today's economy many companies are looking for cost savings. Eliminating muda (waste) is the focus of most lean manufacturing efforts. But two other M's are just as important to making lean work. In fact, focusing on only the eight wastes of muda can actually hamper productivity. Lean is about the elimination of muda, muri, and mura.
The three M's are:
Muda – Non-value-added activities associated with the 8
Muri – Overburdening people of equipment
Mura – Unevenness in your system
Focusing on muda is the most common approach to implementing lean because it is easy to identify and eliminate waste. Unfortunately, those companies fail to understand the connection of the three M's. Stabilizing the system and creating balanced flow is essential to eliminating the three M's
Unevenness happens when volumes move up and down temporarily. This is created by changes in the production schedule, previous processes "pushing" material to the next process, or perhaps empty containers stacking up at processes. Customer orders, machine breakdowns, quality problems, and large production lots are all causes of mura. Leveling out the schedule, heijunka, is fundamental to eliminating mura, which is fundamental to eliminating muri and muda.