Lead Time
What is the difference between lead time and cycle time?
Cycle time is the time the machine actively processes the part, while lead time is the full elapsed calendar time from order release to delivery, including waiting, setup, programming, inspection, finishing, and shipping.
What starts the lead-time clock?
The start point can vary: PO confirmation, drawing approval, order acceptance, payment receipt, or material receipt. It is essential to define the trigger before comparing supplier lead times.
How should a shop quote lead time correctly?
Quote the start trigger, delivery endpoint, and assumptions for material availability, drawing completeness, tolerances, finishing, inspection level, and queue capacity. Lead time varies materially based on these conditions.
Lead time in CNC machining and millwork is the total elapsed time from order confirmation or drawing approval to final shipment. It encompasses quoting, DFM review, programming, material procurement, setup, machining, inspection, finishing, packaging, and logistics—not just spindle cutting time. Typical lead times vary from 3–7 days for simple parts to 10–30+ days for complex assemblies.
On the shop floor, lead time governs scheduling, work-in-progress flow, and delivery promises. A part with a short cycle time can still have a long lead time if it waits for material, first-article approval, tool changes, or inspection capacity. In CNC cells, lead time determines queue position and material release, affecting downstream assembly timing. For millwork, the same logic applies when CNC nesting, edgebanding, veneering, finishing, and hardware installation are sequenced across separate work centers. The calendar time is driven by coordination between these centers as much as by machine speed. Quoting must account for all these steps—not just machining—to set accurate expectations. A well-managed lead time prevents WIP pileups and ensures on-time delivery, making it a critical metric for both the machinist and the customer.
Machine-Time Myopia: Buyers frequently confuse lead time with spindle cutting time, releasing jobs based solely on hours of machining. This ignores queues for programming, setup, and inspection, leading to missed ship dates despite fast cutting.
Specification Drift: Late changes to material, tolerances, or finish introduce procurement delays and re-approval cycles. Even a minor revision can restart preparatory work, extending the calendar significantly.
Tolerance Creep: Tight tolerances and high-finish requirements add setup complexity, tool wear, and inspection time. If quotes assume general tolerances but release demands precision fit-up, lead time expands well beyond the original estimate.