Lesson 6: Buffer management

Planning gets the right work onto the floor at the right time. But disruptions still happen every day: a machine breaks, a part is late, a batch needs rework. How does everyone know what to work on next, without a scheduler rewriting the plan every morning?

One signal: how much of the buffer is used

Every order has a buffer: the time from its release to its due date. Each day, compare how much of that time has gone with how much is left.

Colour	Buffer used	What to do
Green	Less than a third	Nothing. It has plenty of time.
Yellow	A third to two thirds	Keep an eye on it; plan what it needs next.
Red	More than two thirds	Act now. Expedite it; it goes first at every work centre.
Black	Past its due date	Escalate immediately.

The priority rule on the floor becomes almost trivial: work on blacks, then reds, then yellows, then greens. No detailed schedule for the non-constraints; the colour does the scheduling. A shift supervisor can run it from a printed list, and anyone can see why one order goes before another.

Pause and think: why not simply expedite whichever order the customer is chasing hardest?

Because customers should never be listened to
Because it costs more
Because the loudest order isn’t always the one at risk; the colour shows which orders actually need help
Because expediting is never needed

Chasing calls spends scarce management attention on orders that were going to make it anyway, while quiet orders slide into black. The buffer colour points attention at real risk.

Play: The Daily Buffer Meeting

Before you play

The situation. You are the production manager. Every morning at 9 the team meets for ten minutes to decide which orders get extra attention today. About 14 orders are open at any time, and new ones are released every day.

Each card is one order. It has a 10-day buffer: the time from its release to its due date. The bar and the colour show how much of that buffer is used up; the steps show how much of its work is done (6 steps in all).

What you control. On their own, orders move about one step every other day; disruptions hold them back. Each day you can expedite three orders: a supervisor walks each one through, so it is sure to move, sometimes two steps. Tap three cards, then press Next day.

What to watch. The colour counts at the top, and the “stuck yesterday” reason on each card.

Your goal. Ship as many orders as possible within their buffer over 12 days. Afterwards you will see how you compare with expediting whoever shouts loudest, then choose one improvement project and replay the same 12 days.

From firefighting to improvement

Buffer management does more than set priorities. Every time an order turns red, write down why: where it is stuck and what it is waiting for. At the end of each month:

Make a Pareto of the reasons for red orders.
Pick the top one or two causes and launch a focused improvement project on them.
As the reasons disappear, fewer orders turn red, and the buffer can be cut: from six weeks to four, then to two.

This is the TOC process of ongoing improvement. It aims improvement effort at what actually delays orders, instead of at whatever looks inefficient. And a shorter buffer is a shorter lead time you can promise the market.

Two health signals to watch:

Too many reds, roughly more than one order in ten: the protection is at risk. There may be an emerging bottleneck or a policy causing it. Find out before cutting anything.
Almost no reds for a long time: the buffer is probably bigger than it needs to be. Cut it, and gain lead time.

Check your understanding

Answer all five. Get four right to complete the lesson.

1. An order has used 75% of its buffer. Its colour is…

Green
Red
Yellow
Black

More than two thirds used: red. Act now.

2. The priority rule on the floor is…

Whichever is easiest first
Longest batch first
Whichever customer calls first
Blacks, then reds, then yellows, then greens

The colour does the scheduling for the non-constraints.

3. What should be recorded when an order turns red?

Why: where it is stuck and what it is waiting for
Only the customer name
Nothing, just expedite it
The operator’s efficiency

The reasons feed the Pareto that drives improvement.

4. Almost no orders have turned red for three months. What should you consider?

Adding more buffer
Releasing work earlier
Cutting the buffer, which shortens the lead time you can promise
Stopping buffer management

A buffer that is never used is longer than it needs to be.

5. More than one order in ten is red. That suggests…

Everything is fine
The protection is at risk: look for an emerging bottleneck or a policy causing it
The buffer should be cut
Customers are ordering too little

Too many reds means the system is losing its protection. Find the cause first.