Monday, September 16, 2013

Lean Processes, Tip #04

Reduce the Batch Size

"We are what we repeteadly do. Excellence, then, is not an act, but a habit"
- Aristotle.

We have discussed previously (Tip #02) how minimizing the number of handoffs will make your process more agile and more straightfoward. Today we'll be discussing the virtues of minimizing the size of the handoff - and, since the handoff contains a batch of work done, the size of that batch.

Historically, companies have built up manufacturing systems to be efficient in terms of cost-per-product. Traditional management science views the products as cost collectors and therefore one of the way of minimizing unit costs (like overhead) was to increase batch size. More products in the same batch accumulate same absolute overhead (say, for QA), therefore less overhead per unit, right?

Not necessarily. Toyota has long time ago turned this concept upside down with their TPS (the predecessor of the lean manufacturing concept). The actual cost drivers are the activities, if you want to reduce costs per unit, you are better off optimizing activities within processes.

By minimizing the batch size you get several key benefits, crucial especially in an intangibles production system (like, services and software):

1/ smaller batches = faster feedback. In a lean start-up, the build-measure-learn cycle needs to run many times before the invention of a valid business model. Ability to iterate as fast as possible is vital to success. Ideally, the batch size should get as close as possible to 1. If we build excellence by repeating what we do, then let's repeat what we do a whole lot more, and then we'll be excellent much earlier.

2/ smaller batches = less overhead. You will find that, with the right batch size (depending on your size of business), your QA/testing overhead will actually decrease significantly. That's because the QA/testing function will get much more responsive, much more automated, much faster in identifying issues - you would need less QA resources overall, and they will be more evenly allocated across your product cycle.

3/ smaller batches = less risk. You will be able to check your work much faster and correct errors much earlier in the process, before they become ticking bombs in your value chain.

More to come :-)