Tool build time is set by the tool, not by a standard calendar. It scales with cavitation, the number of side actions and lifters, the steel grade, and the surface finish required. A simple single-cavity tool and a multi-cavity tool with several mechanisms are different projects.
What is predictable is the sequence, and where the schedule usually slips:
- Tool design approval happens before any steel is cut. A design waiting for sign-off adds delay and nothing else.
- Machining, EDM, fitting, and polishing is the fixed core of the build.
- T1 samples almost always lead to at least one modification round. Planning for zero rounds is what turns a normal iteration into a missed launch date.
- Changes that add material to a cavity require welding and remachining, and can restart a meaningful part of the build. Changes that remove material are far quicker.
Ask any supplier for a phased schedule with dates per stage rather than one total figure. A phased schedule shows where the risk sits and which weeks are yours to protect.
Read more in what actually drives injection molding lead times.