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What Is a T0 Sample in Plastic Injection Molding?
What Is a T0 Sample in Plastic Injection Molding?
A T0 sample is the first set of parts produced during the initial trial of a newly manufactured production mold. It gives the engineering team the first opportunity to evaluate actual injection-molded parts before the product moves toward mass production.
At Chaozhou Tongheng Technology Co., Ltd., T0 refers to the first formal mold trial and the first molded parts produced for engineering evaluation.
T0 parts are more representative of the intended production process than rapid-prototyped housings. However, a T0 sample is not automatically the final production-approved sample.
For an overview of the earlier stages, read Appearance Prototype vs. Functional Prototype vs. T0 Sample.
When Does T0 Happen?
T0 begins after the Engineering Functional Prototype has been reviewed, required corrections have been incorporated and the buyer has formally authorized tooling.
| Development Stage | Main Result |
|---|---|
| Engineering Functional Prototype Approved | The engineering direction and required corrections are confirmed |
| Tooling Authorized | The buyer approves the final structure and tooling scope |
| Mold Manufacturing | The formal production molds are made |
| T0 Mold Trial | The first molded parts are produced |
| T0 Evaluation | Molding, dimensions, appearance and assembly are reviewed |
| Mold Correction | The mold, structure or process is adjusted as required |
| T1/T2 Trial | Corrected parts are produced and rechecked |
| Production Approval | The golden sample and production requirements are confirmed |
For a clearly defined project, the normal lead time is approximately 40 working days from formal tooling approval to the first T0 mold trial samples.
What Happens During the First Mold Trial?
T0 is a diagnostic trial. Its main purpose is to reveal what still needs correction.
| Trial Activity | What the Tooling and Engineering Team Does |
| Mold installation | Installs the new mold on a suitable injection-molding machine |
| Material preparation | Prepares the planned plastic material for the trial |
| Initial settings | Establishes starting temperature, pressure, speed and cooling conditions |
| First injection shots | Produces the first parts from the formal mold |
| Part removal | Removes and identifies the initial molded parts |
| Visual inspection | Checks for obvious molding and appearance problems |
| Dimensional inspection | Measures important dimensions and part relationships |
| Trial assembly | Tests whether the molded parts and internal components can be assembled |
| Issue recording | Creates the T0 correction and recheck list |
The first machine settings are not necessarily the final mass-production parameters. Process adjustments may be required as the parts are evaluated.
What Is Checked on T0 Parts?
| Inspection Area | Typical T0 Review Points |
| Mold filling and formation | Complete filling, flash, sink marks, warpage, weld lines, flow marks, gates and ejector marks |
| Dimensions and shrinkage | Key dimensions, button and display openings, charging-port alignment, screw posts, snap fits and moving-part clearance |
| Fit and assembly | Housing closure, component mounting, button operation, display alignment and folding or oscillating structures |
| Visible appearance | Gaps, uneven steps, deformation, parting lines, texture, gloss, logo and decorative areas |
| Basic operation | Buttons, display, charging, speed adjustment, folding, oscillation and fan operation after initial assembly |
If trial material or a temporary color is used, the T0 color and finish may not represent final production appearance. Complete reliability, certification and batch consistency still require later validation.
Common T0 Problems
| T0 Issue | What It May Look Like | Possible Correction Direction |
| Short shot | The plastic does not completely fill the part | Adjust the process, gating or mold design |
| Flash | Thin unwanted plastic appears around an edge | Review mold fit, pressure or clamping conditions |
| Sink mark | A visible depression appears on the surface | Review wall thickness, ribs or molding conditions |
| Warpage | The housing bends or twists after molding | Review structure, cooling and process conditions |
| Weld line | A visible line appears where flow fronts meet | Review gating, venting or process settings |
| Poor fit | Housing parts do not close or align correctly | Review dimensions, tolerances or the mold |
| Uneven gap | Assembly gaps vary around the housing | Correct locating features, snaps or dimensions |
| Button misalignment | A button cannot activate the switch correctly | Correct the button, PCB or housing relationship |
| Display misalignment | The display does not align with its window | Correct the display mounting or opening position |
| Abnormal noise | The assembled fan produces rubbing or vibration | Check the blade, motor mounting and housing clearance |
Not every T0 problem requires a product redesign. Some issues can be addressed through mold correction or injection-process optimization.
What Does the Buyer Receive After T0?
The exact deliverables depend on the project, but a T0 review normally produces several useful outputs.
| T0 Output | Purpose |
| T0 molded parts | Provides the first formal-mold parts for review |
| Initial assembled sample | Shows the basic fit of molded parts and internal components |
| T0 issue list | Records cosmetic, dimensional, molding and assembly issues |
| Measurement results | Records important initial dimensions where required |
| Correction proposal | Defines the planned mold, structure or process changes |
| T1/T2 recheck plan | Identifies the items that must be verified in the next trial |
The project does not always require a complex report, but the important issues, actions and recheck points should be documented.
A Simple T0 Issue-Tracking Table
| Part | Issue | Priority | Proposed Correction | Recheck Stage |
| Front housing | T1 / T2 | |||
| Rear housing | T1 / T2 | |||
| Front grille | T1 / T2 | |||
| Button | T1 / T2 | |||
| Display window | T1 / T2 | |||
| Base / handle | T1 / T2 |
This table helps buyers and engineers keep the correction scope clear before the next trial.
What Should the Buyer Confirm?
The buyer does not need to decide how the mold should be technically repaired. The main responsibility is to confirm the issue priorities and acceptance direction.
| Buyer Review Item | Main Question |
| Issue coverage | Have the important T0 problems been recorded? |
| Correction priority | Which issues must be corrected before T1? |
| Correction type | Is the issue handled through process, mold or engineering correction? |
| New request | Is any item actually a new buyer design change after tooling? |
| Recheck scope | Which dimensions, appearance details or functions must be checked again? |
| Next trial | Will the correction be reviewed at T1 or T2? |
| Schedule | When are correction and retrial expected to be completed? |
Clear feedback prevents T0 issue correction from becoming mixed with unrelated new design requests.
Mold Correction vs. Buyer Design Change
The difference affects both cost and schedule.
| Change Type | Meaning | Possible Impact |
| Process adjustment | Changes injection settings without changing the product design | Normally does not change the approved product concept |
| Mold correction | Corrects molding, dimensions, fit or assembly problems | Usually part of the normal trial-and-correction process, subject to scope |
| Engineering correction | Changes a structure that does not work as intended | May require engineering-data and mold changes |
| Buyer design change | Changes approved appearance, dimensions or functions after tooling | May create additional cost and lead time |
For example, correcting a sink mark found during T0 is different from changing the handle shape after the mold has already been made.
Why T0 Is Not the Final Production-Approved Sample
| T0 Sample | Final Production-Approved Sample |
| Produced during the first formal mold trial | Produced after key corrections are completed |
| Used mainly to identify problems | Used to confirm the production standard |
| May contain molding, dimensional or assembly issues | Must meet the agreed approval requirements |
| Mold and process may still require adjustment | Main mold and production data are largely frozen |
| Does not prove batch consistency | Becomes an important reference for production and quality control |
T0 delivery, final sample approval and mass-production start are three different milestones.
What Happens After T0?
The normal sequence is:
-
Inspect the T0 parts and assembled sample
-
Create the issue and correction list
-
Correct the mold, structure or process
-
Produce T1 samples
-
Continue to T2 when necessary
-
Confirm the golden sample and production documents
-
Prepare for mass production
Under a normal correction scope at Chaozhou Tongheng Technology Co., Ltd., mold correction, T1/T2 trials and preparation for mass production usually require approximately 15 working days after T0. A major structural or tooling issue requires the schedule to be reassessed.
Frequently Asked Questions
Is T0 made from the formal production mold?
Yes. T0 parts are produced during the first trial of the new formal mold. However, the mold and process may still require correction.
Can T0 be used as the golden sample?
Not automatically. T0 is mainly used to identify problems. The golden sample should be confirmed after the required corrections and verification are complete.
Does every T0 issue require a mold change?
No. Some issues can be addressed through process optimization, while others require mold or engineering correction.
Can the buyer change the design after T0?
A change remains possible, but changing an approved appearance, dimension or function after tooling may create additional cost and extend the schedule.
How long does it take to receive T0 samples?
For a clearly defined project, the typical lead time is approximately 40 working days from formal tooling approval to the first T0 mold trial samples.
Use T0 to Identify and Correct Problems
T0 is not intended to prove that a new mold is already perfect. Its purpose is to produce the first formal molded parts, identify molding and assembly issues and define the corrections required before production approval.
When T0 findings are recorded clearly and buyer feedback is returned promptly, the project can move into T1/T2 verification with a controlled correction scope.
If you are planning formal tooling for a portable fan or another small appliance, contact Chaozhou Tongheng Technology Co., Ltd. to discuss the T0 trial, correction plan and production-validation process.
