Batching

I was having a chat with someone about ‘batching’ the other day, and wanted to point them to a short and simple post I wrote a few years ago that I thought would assist…so I looked for it…and couldn’t find it…and then realised that I’d never published it on this blog…so here it is:

I wrote a post a bit back entitled One at a time please. In it, I attempted to explain (using my washing up at home¹) about the problems caused by doing things in batches, and that we should strive to shift our processes towards ‘single piece flow’.

This is such an important point that I thought that I would put forward another, hopefully more obvious, example.

Right, here goes:

What do you see here…

…yep, we had two fancy coffee machines in our last works kitchen.

If you were to watch people using them you would note that it is rare that they are both being used…but it does happen…so having 2 machines helps cope with the variation in our demand for a coffee (with spikes in demand unsurprisingly occurring Monday – Friday at around 10:30 and 15:00)

These machines need regular cleaning. I think, from my observations that this is performed weekly.

Cleaning

How about this picture?

Yep, this is what happened when they were both being cleaned.

We used to have a cleaner that liked to come in at around 10:30 (not such a good time really…but that’s a different story), open up both machines and then proceed to perform his cleaning steps one-by one for both machines. Something like this:

Take out both sets of waste drawers, empty them and put them by the sink
Take out both drip trays, empty and put them by the sink
Open up both coffee hoppers and fill them
Open up both creamer hoppers and fill them
Open up both sugar hoppers and fill them
Clean the pipes and connectors of both machines
Wash and dry the waste drawers and drip trays for both machines
Put everything back together for both machines
Close the front drawers of both machines
Wipe the outsides of both machines
…and done. Nice job.

This takes some time…and what can’t happen whilst this is being done?

No one can make a coffee! (or hot chocolate or mocha or …..name some other weird drink made from permutations of powder)

What’s the purpose of the machine? To reliably make (good) coffee as and when someone wants one.

A change in cleaner

I noticed one day that we had changed our cleaner. I also noticed this:

Oh yes! She does exactly the same steps as the earlier cleaner…but she does it one machine at a time.

Now, for those die-hard ‘economies of scale’ fans out there:

There is hardly any time difference between the two cleaning approaches; BUT

We can all still make coffee whilst it’s being done!!!

Even better, she concentrates on one machine at a time (in a state of flow), likely making sure that all is okay with it, potentially causing her to think far wider than just repeating a set of standard steps.

So there you go: a short and simple example of the sense in reducing batch sizes as and when we can 🙂

Anyone for a coffee?

Footnotes

1: My earlier post: If this is the first time you’ve read about batches then please do read my earlier post – it goes into more detail.

There was one among you who, in response to this earlier washing up ‘batch to flow’ post, spent quite some time explaining to me exactly how they emptied their dishwasher, specifying how they had experimented with which items of cutlery were best held between each digits. Nice! You know who you are…Tom 🙂

2: On cleaners: I don’t know why the cleaner changed or why they adopted their different approaches and I make no judgement on either of them. I just really like being able to get a coffee whilst the machines are being cleaned!

3. Simple, and complicated: I know that there are all sorts of batches ‘out there’ (whether temporal or quantity based)…and I know that there are constraints that need to be understood and worked with (you can’t usually just remove, or even reduce, batch sizes – you have to look at the ‘why’)….but the desired target condition of ‘single piece flow’ can be used as a vision to experiment towards, whatever the nature of your batch.

I had an interesting conversation with my youngest son yesterday after dinner. Mum had cooked (a wonderful meal I should add…if she ever reads this), so it was up to me and my boys to wash and dry the carnage left behind.

I washed. I always do the sharp knives first – a touch of OCD according to my wife. There were a number of knives to wash.

No. 2 son picks up the first knife from the draining board, dries it and puts it on the side waiting for the second knife.

Dad:“why haven’t you put that away in the knife block?”;
Son: “because I’m waiting for the other knives first”;
Dad: “why are you doing that?”
Son: “because it will be quicker!” (said in a tone of amazement at the apparent stupidity of my question)
Dad: “why will it be quicker?”
Son: “because I will only have to walk over to the knife block once – duh!”

I let it pass, and carried on to see what happened. Here’s what I observed:

He put the dry knife down on a dirty surface whilst it was waiting ‘in process’ – grrrr, needs washing again!;
He waited (doing nothing) whilst I was washing the next knife. He and his older brother usually have a tussle about the next object, it’s desirability for drying and therefore who’s picking it up…I’m sure there’s a situational comedy sketch in there for the likes of Eddie Izzard!;
He had created a pile (batch) of dried knives and then, somewhat dangerously, picked them all up and walked across the kitchen (bare foot), past his brother and I, and then tried to juggle them in his arms whilst attempting to slot them into the knife block;

He nearly killed his brother in the process….though I can’t be sure as to whether that was his intent.

The funny thing is that we all seem to think, instinctively, that doing things in batches is more efficient. We don’t seem to see all the problems that it can create.

Whenever we deal in batches, we have to:

create the batch;
handle the batch; and then
un-create the batch

…and, whilst this happens:

items ‘wait’ in the batch whilst its assembly and disassembly is completed;
defective items are masked until later in the process…at which point it is probably a problem for many, if not all, items in that batch;
the whole batch suffers (is held up) whilst the item problem(s) are resolved.

I read a similar example on the ‘Leanthinker’ blog recently. It is another nice, short illustrative demonstration of the point.

I also highly recommend the wonderful 1980’s HP video that does much to show the sense of reducing batch sizes. It’s in two circa. 15 min. parts: part 1, part 2 (for info: there is a short ‘part 3’ as well)

Toyota’s phenomenal success (and other Lean Enterprises) lies to a large part down to its focus on the flow of each individual item, rather than the (supposed) efficiency of each activity within the flow.

A reminder that batches take a number of forms: they might be quantitative (e.g. when a load is full) or, more commonly in service value streams, temporal (i.e. at a point in time, such as monthly, weekly or daily)

Let’s see if we can re-programme our brains from seeing batches as a good thing to seeing flow as the ultimate prize.

I’m sorry to say that, after my ‘knife-juggling son’ observations, I attempted to explain the above to him and was accused (as usual) of “giving him a lecture”. I saw his eyes roll back in his head, I can’t win! I think mum was happy though: she was oblivious to the major life lesson being attempted.