GlossaryKind of term: Manufacturing termLead time
What is lead time?
Lead time is the period between order and delivery that you promise the customer; it covers material, machining, outsourcing, inspection and waiting.
It is stated in working days, weeks or as a delivery date. It counts every step: ordering and receiving material, programming, the queue for the machine, the operations themselves, outsourced finishing including transport both ways, inspection, packing and transport. What delivery means follows from the delivery terms: ready for collection at your premises or delivered to the customer. The material's own lead time is a separate period; if the material is not in stock, it decides when you can start.
What does lead time depend on?
How long an order is under way depends less on machining time than on what surrounds it. In shops running many different orders, an order often spends most of its throughput time waiting: for material, a free machine, a released program, the subcontractor or the inspection room. Machine load matters too: as a machine approaches full capacity, waiting times rise steeply. Sequence counts as well: hardening usually comes before grinding and anodising after machining, so those steps cannot run in parallel. An outsourced step in the middle of the route adds transport both ways and a queue at the subcontractor.
How does lead time work in practice?
A lead time added up from operation times is usually too short. A more realistic one is built per step of the route: expected time, external turnaround for outsourcing and material, inspection points and current load, set against the requested date. If it does not fit, you can change the route, take material into stock, request an outsourced step earlier or agree a partial delivery with the customer. Faster machining shortens lead time mainly when the machine itself is the bottleneck; against a week of waiting at a subcontractor it changes little.
What is lead time often confused with?
Cycle time is the time per piece on one machine; lead time is the whole period to delivery. Quote turnaround time runs from request to quote and so comes before the order. And the lead time you promise is not the internal throughput time on the shop floor: material, transport and a buffer for uncertainty come on top.
Frequently asked questions
Why does delivery take longer than the machining time?
Because an order often spends most of its time waiting: for material, for a free machine, at the subcontractor or in the inspection room. How much depends on machine load, the route and how many steps happen outside the shop.
Which part of the lead time can I influence myself?
Mostly the waiting: material in stock or ordered early, outsourcing requested as soon as the order lands, the job planned early. Faster machining helps mainly when the machine is the bottleneck.
Does transport count in the lead time?
That depends on the agreed delivery terms. If you deliver ex works, lead time ends when the goods are ready for collection; if you deliver to the customer, transport counts. Put the delivery terms next to the lead time on the quote.