Recent examples from clients struggling with non-Lean scheduling methods reminded me of the importance of a fundamental principle of Lean – “do today’s work today”. This means no late deliveries, capacity equal to demand, and no overproduction.
It’s really a basic philosophy of business but it’s harder than it seems. Especially when you are depending on an information system that doesn’t contain the information you need.
What you need to be able to do today’s work today:
1) Know what today’s work is (understand daily customer demand)
2) Know how much time that work takes (understand process cycle times for all work elements)
3) Know your capacity at each process / workstation
How many companies can say they meet all three conditions? In our experience of working with or visiting over 100 companies, very few can. What then, are some remedies?
First you need a way to break down scheduling of work down to daily buckets at a minimum. Buckets of 2 to 4 hours area preferable. Within this daily schedule, there should be no changes. After all, it’s today’s work. Do it today.
Even if you know what today’s work is, some companies choose to today’s work change, today. When today’s schedule can change today (schedule changes, expedites, drop-ins) it introduces complexity and waste to the system. In short, if you have less than a firm 1-day schedule, you will damage your ability to do today’s work today.
The best way to avoid needing to make daily schedule changes is to increase your velocity by reducing lead-time, allowing you to respond quicker than your customer expects. If you are batching, going to one-piece flow will certainly help. Of course it helps if your capacity to supply exceeds demand, and in our experience you can recoup between 25% and 35% capacity by firming up your schedule and not introducing daily changes.
Second, go to the Gemba and measure everything you do. How many seconds does it take to do each task? Don’t depend on standard times, times in the system, or estimates. Doing so is taking a costly shortcut. As you observe and time processes, look for the true value added time (transforming material or information) and make note of all the wasted time or effort. There is your opportunity for future kaizen and increased capacity.
Third, make good use of the Table of Production Capacity by Process and the formula for calculating capacity. Take into account not only actual value added time but loading time, walking time, change over time (per piece), etc. and understand what each process should take.
There will inevitably be losses of capacity, and this is where SMED, TPM, and other Lean tools come in handy. Whenever the theoretical capacity is not being met, attack the losses with kaizen.
Most MRP systems do not readily support this type of model. Several of our clients have had success customizing Microsoft Access reports and processes to give them the capacity vs. demand information they need. Understand first what you need to do today’s work today, then make technology an ally of your Lean efforts and kaizen activities.