Views: 0 Author: Tonney Shao Publish Time: 2026-09-10 Origin: Abery Mold
Most buyers know that a mold gets "trial run" before it goes into production, and most buyers know to ask for a trial report. Far fewer buyers actually know what should be inside that report — which means a lot of trial reports get a quick glance and a rubber-stamp approval, when they should really be getting read line by line.
That's a problem, because the trial report is the single clearest window you'll get into whether your mold is actually ready. This guide walks through what a proper T1 and T2 trial report should contain, what each of the two trials is supposed to prove, and what questions to ask before you sign off on samples and move toward production.
Visual approval — holding a sample part and deciding it looks acceptable — catches obvious problems: gross warping, visible short shots, obvious flash. It does not catch dimensional drift that's within "close enough by eye" but outside your drawing tolerance, and it does not tell you whether the process that produced this particular sample is repeatable at production speed. A trial report exists to answer the questions that eyeballing a part cannot.
A trial report that's just a few photos and a "looks good, approved" note is not a trial report — it's a gesture. A useful one has three distinct sections, and if any of them is missing, you should ask for it before you approve anything.
This is the core of any real trial report — a measured comparison of critical dimensions against your drawing tolerances, not a general impression of fit. For each critical dimension called out on your drawing (or agreed upon during DFM review), the report should show:
The nominal (target) dimension and its tolerance range from the drawing
The actual measured value from the trial sample
Pass/fail status for each dimension
The measurement method used (CMM, calipers, gauge, etc.) and how many samples were measured
If your report only lists a handful of "key dimensions" without reference to your drawing's tolerance callouts, ask which dimensions were measured and why those were chosen. A dimension that's out of tolerance by a small margin on T1 is normal and expected — that's exactly what T1 is for. A dimension still out of tolerance on T2, after supposed corrections, is a different and more serious conversation.
Alongside the dimensional data, the report should document any visual or surface defects observed on the trial shots, not just state that "some parts had minor issues." Common defects that should be explicitly logged include:
Sink marks — depressions on the surface, usually opposite thick sections or ribs
Flash — excess material at parting lines, gate areas, or ejector pin locations
Flow marks / weld lines — visible lines where plastic flow fronts met or where flow patterns are visible on the surface
Short shots — incomplete fills
Warping — dimensional distortion from uneven cooling or internal stress
A useful defect log ties each observed defect to a suspected cause and a proposed corrective action — not just "defect found," but "sink mark at rib base, likely due to insufficient cooling time in this area, proposed fix: adjust cooling channel layout / packing pressure." If your supplier's report lists defects without proposed causes or fixes, ask directly what's driving each one before you approve moving forward.
The dimensional results and defect log only mean something in context of how the shot was actually made. A complete trial report should record the process parameters used to produce the samples being evaluated, including:
Barrel and mold temperatures
Injection pressure and speed
Packing/holding pressure and holding time
Cooling time and total cycle time
This matters for two reasons. First, if a supplier "tunes" the process heavily to get one good-looking sample batch, but that exact combination of parameters isn't documented, you have no way to confirm the same result will repeat at production volume. Second, if a dimension is borderline, knowing the process parameters used tells you whether there's still room to adjust the process itself before concluding the mold needs rework — sometimes a dimensional issue is a process problem, not a tooling problem, and the fix is cheaper and faster than it looks.
The first trial (T1) is a structural test, not a final exam. Its job is to reveal whether the mold, as built, has any design or construction issues that weren't caught during DFM review or that only become visible once the mold is actually running — cooling layout problems, ejection issues, gate location problems, dimensional deviations that point to a core or cavity built slightly off from the design intent.
It is normal, and even expected, for T1 to surface some issues. A T1 report with zero findings is not necessarily a good sign — it can just as easily mean the inspection wasn't thorough enough. What matters is whether the issues found are addressable through mold correction (adjusting steel, reworking a cooling channel, polishing a surface) rather than issues that indicate a fundamental design flaw that should have been caught earlier.
The second trial (T2) exists to verify that the corrections made after T1 actually worked — and to confirm that fixing one issue didn't introduce a new one elsewhere. T2 is where you should be comparing directly against the T1 report: did the specific dimensions and defects flagged in T1 actually resolve, and did anything new show up that wasn't present before?
This is why it matters to keep both reports and read them side by side rather than treating T2 as a fresh, standalone approval. A T2 report that doesn't reference what was found in T1 and explicitly confirm resolution isn't giving you the comparison you actually need.
Before signing off on T1 or T2 results, it's worth asking your supplier directly:
Which dimensions were measured, and how do they compare to my drawing tolerances — not just "within spec," but by how much margin?
What defects were observed, what's the suspected root cause of each, and what corrective action is proposed or was already taken?
What process parameters produced these samples, and are those parameters realistic to hold at production cycle times and volumes?
For T2 specifically: which T1 findings does this trial resolve, and is there anything new that wasn't present in T1?
As a general rule, you're ready to approve production when T2 results show all critical dimensions within tolerance, no unresolved defects from the defect log, and process parameters that are realistic to sustain at production volume — not parameters that only work in a slow, carefully babysat trial run.
A third trial isn't a failure — it's the right call if T2 still shows unresolved dimensional issues, if a new defect appeared that wasn't in T1, or if the process parameters used to hit spec are clearly not sustainable at production speed. Approving samples under those conditions just moves the problem downstream into full production, where it's far more expensive to fix.
This is exactly why the free DFM review that should happen before a mold is even built matters so much — the fewer structural issues that make it to the T1 stage, the fewer rounds of correction you need before signing off. At Abery, DFM optimization is provided free of charge before tooling starts, and the standard T1+T2 trial process is designed around catching and resolving issues in two rounds rather than three or four.
Written by Tonney Shao, CEO of Abery Mold. Tonney has spent 16 years helping overseas buyers source injection molds and plastic parts from China, and has personally overseen mold projects for clients including Schneider Electric and Honda's supply chain. Contact: tonney@a-mold.com | WhatsApp: +86 139 2521 4356
