Mold Trials: T0, T1 and Final Approval
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A new mold rarely makes good parts on its first shot. It goes through a series of trials, usually called T0, T1, T2 and so on, with adjustments in between. Knowing what each one is for helps you judge progress and avoid surprises. Naming varies, and some shops call the first trial T1.
T0: does it work?
The first time the mold runs. The toolmaker checks that it fills, ejects, cools and cycles without damage. Parts may be short, flashed or cosmetically rough, and that's normal. The output is a list of fixes: venting, gate size, ejection, cooling.
T1: first samples
After the T0 fixes, the mold makes samples for you. This is where measurement starts: a dimensional report against the drawing, often per cavity, plus a cosmetic check of the faces you marked. Expect some dimensions out of tolerance. Critical features are often left steel safe on purpose, so they can be brought in by removing steel.
T2 and beyond: tuning
Each round adjusts steel and process to bring dimensions in. Two or three rounds are common for a new part, more if the design changed or the tolerances are tight. Every round costs time, shipping and sometimes money, so freeze the design before steel is cut and agree up front which dimensions are critical.
Texture and finish
Texture is usually applied after the dimensions are approved, because adjusting steel through a texture is hard. Check the textured samples again: texture changes how parts release and how they look near the gate.
Final approval
Final samples come from a stable process with the settings recorded. For automotive work that usually means a capability study and a PPAP submission. Approved samples are kept as references, and the process sheet stays with the mold.
What to ask for at each trial
- A trial video and the process sheet: temperatures, pressures and times.
- Samples from every cavity, labeled by cavity number.
- A dimensional report against the drawing, with out-of-tolerance items highlighted.
- Photos of any cosmetic defects, and the plan to fix them.
If your toolmaker is overseas, these records are how you follow progress without being there. See tooling.