What a T1 mold trial is
A T1 mold trial is the first formal test run of a new injection mold on a molding machine, using the intended material, to produce sample parts for evaluation. The parts are measured against the drawing, checked for cosmetic defects and fitted with their mating parts. The result is a list of corrections to the tool or process, followed by the next trial, T2, and so on until the parts are approved.
Expect T1 parts to need corrections; a new tool almost always does. What matters is that the T1 parts are evaluated thoroughly, so problems are found together in this round instead of one at a time across several more.
T0, T1, T2: the naming varies
Toolmakers do not all number trials the same way. Many run an internal T0 to check that the mold fills, cools and ejects, sometimes without sending parts to the customer. Others call the very first shots T1. Agree in the tooling contract what each round means, how many rounds the price includes and what you receive from each.
A typical sequence:
| Round | Usual purpose | What you should receive |
|---|---|---|
| T0 (if used) | Toolmaker’s own check of filling, cooling and ejection | Often nothing formal; ask |
| T1 | First samples for measurement and fit | Sample parts, dimensional report, trial report, issue list |
| T2, T3 | Verify corrections, refine dimensions and process | Updated report showing each issue closed |
| Final, with texture | Texture or polish applied, final approval | Approved samples, which may later become golden samples |
Texture is usually applied after dimensions are approved, because texturing the cavity surface is hard to undo and modifying a textured tool is more difficult.
What to check on T1 parts
Dimensions. Measure the critical dimensions on the drawing and, in a multi-cavity mold, measure parts from every cavity. Ask for the supplier’s measurement report and spot-check it.
Fit and function. Assemble T1 parts with their mating parts and the electronics. Many problems only appear in assembly: snap fits that are too tight, bosses that crack under screws, gaps and steps at the parting line.
Cosmetics. Look for short shots, flash, sink marks, weld lines, flow marks, warpage, gate marks and ejector pin marks on visible surfaces.
Process. Ask for the molding parameters used, such as melt and mold temperatures, injection and holding pressure, and cycle time. A part that only comes out right at an extreme setting will be hard to make consistently in production.
Recording T1 results
Work from one issue list per part that both sides share. For each issue record:
- Part number and cavity number
- Description, with a photo or measurement
- Proposed correction, and whether it changes the tool, the process or the design
- Who pays: a toolmaker error, or a design change on your side
- The trial round in which the fix will be verified
Label and keep T1 samples so later rounds can be compared with them.
T1 versus prototype parts, FAI and DVT
T1 parts are the first parts from the production tool. That separates them from prototype parts made by 3D printing, CNC machining or soft tooling: they show how the real steel, gates and cooling behave with the real resin. They are still not production parts. The tool will be corrected and the process window is not yet fixed, so a T1 dimensional report feeds the next correction rather than approving anything.
Formal first article inspection comes later, once the tool is approved and the molding parameters are locked; that page compares the later approval steps side by side. Reliability and certification testing of the whole product belongs to DVT, which is usually built with parts from corrected production tooling.
Common mistakes
- Judging cosmetics on untextured T1 parts and approving the look too early.
- Checking parts on their own instead of in a full assembly.
- Measuring one cavity and assuming the others match.
- Accepting “will fix at T2” without a written list.
- Pushing the process to its limits to make a part pass.
- Changing the design between trials without telling the toolmaker which dimensions are affected.
Where Zefinity helps
Trial rounds are where tooling schedules often slip. As part of supplier coordination and manufacturing engineering support, Zefinity follows trials with the toolmaker, keeps the issue list current and separates toolmaker corrections from design changes, so each round closes more problems than it opens. The wider sequence is covered in tooling and injection molding.
Frequently asked questions
How many mold trials are normal?
There is no fixed number. Simple parts may be approved after one or two rounds of correction; complex cosmetic parts or tight-tolerance assemblies often take more. What matters is that each round closes a defined list of issues. Agree how many rounds the tooling price includes and how extra rounds are charged.
Can T1 parts be used for testing?
For fit checks and early engineering tests, yes, as long as everyone records which trial and cavity the parts came from. They should not be used for final cosmetic approval or certification testing, because the tool and the molding process will still change.