The size of a batch is not written in stone.

The size of the batch is under the control of management.

Maybe by being smart about the batch size, we can try to improve the process.

We could potentially increase capacity or we can reduce the inventory level.

But how do you set a good batch size? What is a good batch size.

This is the topic of this session. In the previous session, we chose the

batch size B based on demand. We pretty much ignored the rest of what's

setup. Now, consider again the process of the apparel making.

Recall the four steps in the process including the cutting department, section

one, section two and finally, the finishing.

Recall that only the first step, the cutting department, actually had setups.

Now, let's first consider and arbitrary batch size of B equals to five.

With B equals to five, our capacity to cutting is, remember the formula, B

divided by the setup time plus B times the processing time which turns, in this case,

to five divided by twenty plus four times five, and that is five divided by 40 which

is 0.125. Then, the next step we have eight divided

by 40. Notice there's no set-up time here and so

we can just use our good old formula, number of workers divided by the

processing time. So, eight by 40 that is 0.2, five by 30

which is 0.1666. And then, one divided three which is

0.333. So, for batch size of B equals to five, we

see that the bottleneck is going to be at the cutting machine,

Right? You notice that the capacity here is at

its minimum. Now, that was just an auditory backslash

of B equals five. Let's consider another one.

Say, B equals to 50. Now, at B equals to 50, here's what's

going to change. At the cutting machine, we now have to

look at 50 divided by twenty plus four times 50, and that is simply 50 divided by

220, which is roughly 0.227. And the other capacities have not changed,

because there was really no setup involved.

Their capacity is independent of the batch size and remains at 0.1666 for section

two, 0.333 for the finishing department. Now, look what has happened.

By increasing the batch size on B equals five to be 50, we have been able to shift

the bottleneck. Now, the bottleneck is at section two.