Lead time

Lead time is how long the customer waits, from placing the order until receiving it. In a plant, most of that time is not the part being machined: it is the order waiting in a queue, material that has not arrived, the part sitting between one operation and the next.

How it works

To cut lead time, the first step is separating value-adding time (production) from waiting time. The machining cycle is usually a small fraction of the total. Queues, missing material, long setups, drawing approval and end-of-line inspection are where the days go. Measuring each step, with dates recorded automatically, shows where to act and makes the date promised to the customer more reliable.

Practical example

A part with 40 minutes of machining had an 18-day lead time. Mapping showed 6 days waiting for material, 7 days queued at the machine and 2 days waiting for inspection. With a reorder point for the bar stock and weekly scheduling, lead time fell to 8 days without buying a machine.

Common mistakes

• Confusing lead time with cycle time and promising impossible dates.
• Measuring only production and ignoring waits for material and approval.
• Flooding the floor with released orders, which lengthens every queue.