Manufacturing Constraints: When Scheduling and Capacity Don’t Meet

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Posted by: briansittley Comments: One Comment 0 Post Date: January 16, 2010

A recent article in APICS Magazine reminds us of the complexity of accurately and efficiently planning production in the manufacturing environment, whether you’re in a continuous or a batch environment.

As David Turbide, an independent consultant points out, traditional enterprise planning involves scheduling materials via Material Requirements Planning (traditional MRP) but seldom takes into account whether there is sufficient capacity to carry out the ultimate plan.

This “plan materials first, then check capacity” logic has been around since MRP was first automated in the 60’s.  Too often, conflicts between supply/production and capacity are detected, and changes are made on the fly, often made during or just before setup, and usually involving trade-offs of inventory vs. schedule disruptions or overtime.

The math to resolve this, if even available, is complex.  Rules that drive the process must often be broken, and blindly following rules seldom leaves every production need satisfied.  Besides, humans can still make better ‘special judgments’ than software when exceptions become the rule.

One effective solution comes courtesy from our old friend Donn Novotny, President of The Goal Institute.  Donn’s drum-buffer-rope (DBR) logic and the long heralded Theory of Constraints provide practical, real-world solutions to thorny production scheduling problems.  We’ll cover more of the basics in our next article, but you can find decent overviews here and here.

Donn, by the way — and many don’t know this — was actually the role-model for Alex Rogo, lead character in the seminal manufacturing ‘novel’ of the 1980’s entitled The Goal, which became one of the world’s best-selling business books ever.  We at PSSI have been friends with Donn (who lives nearby) for years, and have sponsored him frequently at customer events and seminars.  Donn and I are even members of a local consultants’ roundtable called the Business Improvement Group, and we’ve referred Donn to clients who faced the very kind of constraints that Donn is an expert at solving.

For those not familiar with these topics, we’ll highlight DBR and TOC approaches a bit this week.  One thing’s for sure: For every problem in business these days there is no shortage of people with proposed solutions.

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