Late deliveries are usually a planning problem, not a production one

When dispatch reliability drops, the shop floor gets the attention. In most of the plants I have worked in, the shop floor was not the constraint.

The pattern repeats: sales commits to a date, planning finds out late, purchase reacts later still, and production absorbs the compression.

Before buying capacity, measure the gap between order confirmation and material availability. If it is wider than your production lead time, more machines will not help.