To expand on this:
Lead times can be set on: Default order, Site specific order, item coverage, and the trade agreement.
How the trade agreements settings work depends also on the Master planning parameter i.e.is the 'Find trade agreements' parameter checked?.
When you use delivery date control you can usefully opt to setup the lead time in the trade agreement. You have the ability to override the lead time at an item default order, or with site specific settings but being able to set it in the trade agreement gives you the ability to have a setting for a group of customers/vendors or for a specific customer/vendor. On the purchasing side under setup, pricing, there's a menu option called "Activate price/discount". That brings up a screen with check boxes to enable trade agreement journals for purchase orders for parts, vendors, vendor groups, etc. If you haven't check/enabled anything over here, but only told MRP to use these, then even though it will let you create and post the journal, MRP won't see and use it without the purchasing setup also enabled.
When you do not have a Primary vendor on the Purchase fast tab on your item master, the Ax system will search for a vendor in purchase price trade agreements. the business logic is to allow master planning to search the Purchase price trade agreements, and then select either the cheapest, or the fastest vendor.
Often, items only have one vendor – and the simplest approach is to set up that vendor as the primary vendor in the item master record
. Even when there is more than one vendor, there is usually a preferred , so the simplest setup is still for that vendor to be setup as the primary vendor in the item master.
As general advice always select "Disregard lead time" on your trade agreements when you are not using the lead time field on the trade agreement - otherwise the Ax system might interpret the record value meaning that you have a zero lead time.
If you get regular deliveries e.g. weekly but lead time is e.g. monthly then you could make the item coverage lead time 'week' and your purchase agreement lead time 'one month'.
P.S. Its usually best to work with calendar days, not working days. Ships may keep sailing over a weekend.
