Lead time

Lead time counts everything that happens between order and delivery: buying and receiving material, work preparation, waiting for a free machine, the operations themselves, any outside work such as hardening or surface treatment, inspection, and packing and shipping.

What it means for the calculation

Lead time is a promise of its own alongside the price, and often the promise an order is won or lost on. The largest blocks are usually the material lead time and the outside work, not the machine time. A part that has to be hardened and ground after milling leaves the building and comes back, and that round trip often takes longer than all the operations combined. A rush order usually shortens lead time by skipping the queue, not by cutting faster, and that moves the problem to the other orders in that queue.

Where this comes up

In the quotation as a delivery promise, in capacity planning as waiting time for a machine, and in the routing as the sum of operations, waiting times and outside steps.

Common mistakes

Making a delivery promise from the summed operation times, without counting the queue, the material lead time and the outside work. Also accepting a rush order without checking what it does to the other orders in the queue.

Is lead time the same as cycle time?

No, cycle time is the time per piece on one machine; lead time also counts all the waiting.

Why is material often the largest block?

Because a size or alloy that is not in stock can take weeks, and only then can the rest start.

Can lead time be shortened without cutting faster?

Yes, usually by working on the queue, the outside work and the material purchasing.