I am not the Sears catalog. This is a build-to-order world, and things can go wrong. I would not accept a PO that included a late penalty as a matter of "company policy".
I might negotiate a deal that had a carrot and stick, but it would be a one-off.
When I confirm an order, I am confirming everything on the PO, including the ship date. That means I am confident I can make the date. If something happens like a machine goes down, I let the customer know right away. But I can't control everything, and I sure can't control the schedule of the anodizers, so I won't guarantee their performance.
It's bad enough that we have to quote firm fixed prices- the local car repair shop sure as hell isn't expected to work on those terms.
When was the last time you went to a customer and said "I missed the estimate, it took longer than I expected" and they said "no problem"? The really good customers will work with you, but most people will just say tough luck.
The only way to absolutely guarantee a delivery date is to have the parts already finished. If they wand to penalize you for late delivery, they should give you a blanket PO so you can inventory their parts.