Push, Pull...or Flow: Part Tres
In my last post, I gave an example of what I meant by flow as compared to push or pull.
Here's an example of what it looks like when there's no flow.
Changeover: Standard Time - One Hour/Actual Time: Three Hours
Can't find the tools to do the changeover with because the supervisor took them to another machine.
Find some of the tools, make do.
Tooling isn't ready or can't be found.
Tooling is ready but doesn't quite fit.
Tooling finally installed.
Can't get first good part.
Finally get first good part
Problems with equipment but maintenance isn't available so run at a lower rate.
Supervisor changes run settings in the middle of the run without telling you. You make an hour of scrap trying to figure out what the heck went wrong.
Tooling is not good enough to hold dimensions at rate. Lower rate some more.
I'm making all this up as I go, of course, but you get the idea, I'm sure.
Notice that I haven't said whether these parts are being pushed (scheduled according to a forecast) or pulled (scheduled because of an order or a kanban). Whatever we call it, we don't have flow. And if we don't have flow, it doesn't matter what we call it.
And let's imagine that this is just one of several process steps. Our "flow problems" start to compound.
The point is that whether you push or pull, you MUST create flow. You might need to push because the product is very cyclical. Good flow will mean it costs you less to have product in inventory. (The fact is, a lot of push is done because of all the sorts of problems mentioned above.) And you'll probably be able to reduce your inventory a bit. If you can, you'll pull. And flow is essential to pull. I work with small job shops that have never done anything but pull....get an order, make the order. But they don't have flow (or didn't until they started implementing agile methods) and it hurt their costs (scrap, overtime) and customer service (late deliveries, customer rejects). Push when you must, pull when you can....but always work for better flow.
Here's an example of what it looks like when there's no flow.
Changeover: Standard Time - One Hour/Actual Time: Three Hours
Can't find the tools to do the changeover with because the supervisor took them to another machine.Find some of the tools, make do.
Tooling isn't ready or can't be found.
Tooling is ready but doesn't quite fit.
Tooling finally installed.
Can't get first good part.
Finally get first good part
Run 1000 Parts: Standard Time - Five Hours/Actual Time: Eight Hours
Material is bad but there isn't a substitute so you make it work.Problems with equipment but maintenance isn't available so run at a lower rate.
Supervisor changes run settings in the middle of the run without telling you. You make an hour of scrap trying to figure out what the heck went wrong.
Tooling is not good enough to hold dimensions at rate. Lower rate some more.
I'm making all this up as I go, of course, but you get the idea, I'm sure.
Notice that I haven't said whether these parts are being pushed (scheduled according to a forecast) or pulled (scheduled because of an order or a kanban). Whatever we call it, we don't have flow. And if we don't have flow, it doesn't matter what we call it.
And let's imagine that this is just one of several process steps. Our "flow problems" start to compound.
The point is that whether you push or pull, you MUST create flow. You might need to push because the product is very cyclical. Good flow will mean it costs you less to have product in inventory. (The fact is, a lot of push is done because of all the sorts of problems mentioned above.) And you'll probably be able to reduce your inventory a bit. If you can, you'll pull. And flow is essential to pull. I work with small job shops that have never done anything but pull....get an order, make the order. But they don't have flow (or didn't until they started implementing agile methods) and it hurt their costs (scrap, overtime) and customer service (late deliveries, customer rejects). Push when you must, pull when you can....but always work for better flow.
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