Why is it harmful to pad Lead Days and Job Days?
Padding lead times is counter-productive
With just in time manufacturing it is counter-productive to pad or inflate item Lead Days and Job Days settings because it distorts Time to Shipment targets for sell items and you lose the ability to track late POs and late starting jobs.
Lead times are inter-connected
Item lead times are inter-connected. Whenever an item has a To Order policy, its Lead Days and/or Job Days contribute to the lead times of higher level items. So whenever you pad or inflate lead times at one level, it can inflate lead times at the next higher level. Furthermore, the inflation effect magnifies at each higher level and can result in severely distorted Time to Shipment targets for top level items. This defeats one of the core purposes of Time to Shipment MRP, which is to achieve realistic and reliable ship dates.
Realistic PO due dates are important
The P item standard Lead Days establishes PO due dates. If you pad or inflate Lead Days, PO due dates are not realistic and you lose the valuable ability to track and expedite late POs in the PO Schedule.
Realistic job dates are important
The M item standard Job Days establishes job start and finish dates. If you pad or inflate Job Days, planned start dates are not meaningful and you lose the ability to track late starting jobs in the Release Jobs screen.
Meet don’t beat the schedule
To be successful with Time to Shipment MRP, make it your planning objective to meet, not beat the schedule. Strive for realistic Lead Days and Job Days so that Time to Shipment targets are plausible and achievable and so that job and PO dates provide the feedback needed for staying on schedule so that orders get shipped on time.
