Most lead-time discussions focus on machining speed. But on complex assemblies, machining is rarely the bottleneck. The bottleneck is usually waiting — for material, for inspection, for paint to cure, for the next cell to free up.
Where the days go (typical 6-week job)
- Material procurement: 7–10 days
- Active machining: 4–6 days
- In-process queue waiting: 8–12 days
- Finishing (heat treat, plating, paint): 5–7 days
- Inspection and FAI: 3–5 days
- Assembly + final test: 3–4 days
Three changes that work
- Order long-lead material at quote time, not PO time
- Move first-piece inspection to in-process — don’t queue it for batch end
- Build sub-assemblies in parallel with finishing of the next-level parts
None of these add capacity. They just remove queue time, which is where the days actually live.