Heijunka Archives

Why Demand-Driven MRP (DDMRP) is Not Lean (Part 2)

Demand-Driven Material Requirements Planning, or DDMRP in short, promises to be the first real innovation to MRP since the invention of MRP. Furthermore, in one of its white papers, the Demand Driven Institute states that “Lean Finds a Friend in DDMRP” (2011). DDMRP is positioned as integrating Lean, the Theory of Constraints (TOC) as well as Six Sigma whilst fundamentally innovating the traditional MRP (and DRP) planning approach. What I think of it? Some parts are OK, but most of it still has nothing to do with Lean. In a series of two posts of which this is the second (the first can be found here), I’ll try to explain my views and hope this may help you and your company in making the right decision when looking at your values, your thinking, your philosophy and your strategies.
(more…)

Why Demand-Driven MRP (DDMRP) is Not Lean (Part 1)

Demand-Driven Material Requirements Planning, or DDMRP in short, promises to be the first real innovation to MRP since the invention of MRP. Furthermore, in one of its white papers, the Demand Driven Institute states that “Lean Finds a Friend in DDMRP” (2011). DDMRP is positioned as integrating Lean, the Theory of Constraints (TOC) as well as Six Sigma whilst fundamentally innovating the traditional MRP (and DRP) planning approach. What I think of it? Some parts are OK, but most of it still has nothing to do with Lean. In a series of two posts (the second one of this series you can find here), I’ll try to explain my views and hope this may help you and your company in making the right decision when looking at your values, your thinking, your philosophy and your strategies. (more…)

Muri and Mura: Kingman’s Seven Lessons

More than 100 flights cancelled and delays of sometimes over 20 hours with consequences for over 76,000 travelers. That was the sad result of Vueling’s planning policies according to an article in last week’s Dutch Financial Times and (in English) in El Pais. Experts stated that Vueling scheduled more flights than they even had airplanes and staff. In between flights they apparently scheduled no safety time meaning that even the slightest hiccup leads to a snowball effect all subsequent flights. In the end, Vueling’s personnel therefore cannot take the required breaks resulting in even further delays and cancellations when the plane needs to be grounded and the personnel needs to rest. This case represents a good example of Kingman’s formula, part of queuing theory, and of how not using these insights results in poor planning, overburdening (Muri) and unevenness (Mura) and in the end disastrous results for lead times and service. (more…)

Using “Every Part, Every Interval” (EPEI) in Pull Flow

End of 2014, early 2015, Christoph Roser wrote an interesting series of posts about leveling and heijunka that already triggered me at the time, as I have personally been involved in many leveling, pull flow, kanban and EPEI initiatives during my career. And although in many cases I can align myself with Christoph’s views, in some aspects I don’t think his posts have done justice to the way in which leveling, pull, EPEI and the one-piece flow ambition can actually work together. Only recently, however, I have taken the time to put my thoughts on paper. Bear with me, as this post is more technical and longer than my typical posts. (more…)