T0–T4 Dynamic Mold Trial

Injection Mold Trial Checklist: What to Check During T0–T4 Run-Off

Q: When should a mold trial be held or repeated?

Use HOLD when an unresolved condition makes continued sampling unsafe, technically unreliable or difficult to interpret. Use RETRY after a tooling correction or controlled process change when the affected evidence must be regenerated. Examples include unstable mold movement, unreliable release, unresolved fill behavior, missing traceability or a correction that still requires verification.

Engineer reviewing injection mold trial samples and run-off checks beside an injection molding machine — Trial review should connect molding conditions, cavity-tagged samples, observed mold behavior and open findings to the current trial stage.

This injection mold trial checklist focuses on the dynamic checks performed after the mold is mounted in the press. It follows the trial from initial setup and first resin injection through fill progression, V/P transfer, packing, cooling, mold opening, ejection, repeatability and later process-boundary review where required.

Pre-mount mechanical, utility, electrical and machine-interface readiness should already have been reviewed before this stage. If those conditions are still open, complete the Injection Mold Pre-Trial Inspection Checklist before beginning powered trial work.

Setup and first fill: confirm machine setup, basic mold function and controlled first-shot behavior.
Filling and formation: observe short-shot progression, cavity balance, V/P transfer, packing and cooling response.
Dynamic mold behavior: check opening, side actions, ejection, part release and visible defect onset under actual molding conditions.
Trial disposition: record findings clearly enough to decide whether the next step is CONTINUE, HOLD or RETRY.

Stage naming note: T0, T1, T2, T3 and T4 definitions vary by customer, toolmaker and project. The sequence on this page is a practical SPI working model for trial execution; project-specific stage definitions and approval authority should follow the agreed mold trial plan.

View T0–T4 Trial Checks →

Checklist Scope

What Does This Injection Mold Trial Checklist Cover?

This checklist is for dynamic mold-trial execution after the tool is mounted in the injection molding machine. It helps the trial team observe mold behavior, molded-part formation and process response at each stage without turning the page into a full approval, validation or data-recording procedure.

What This Checklist Covers

Machine and first-shot setup: basic molding-machine conditions, safe first resin injection and initial tool response.
Fill progression: short-shot sequence, cavity balance and visible filling behavior.
V/P, packing and cooling response: how the molded part develops as transfer, hold and cooling conditions are established.
Dynamic mold behavior: mold opening, side-action movement, ejection, part release and other behavior that can only be observed under molding conditions.
Visible trial findings: flash, burn marks, short shots, sticking, drag marks and other defects observed during sampling.
Trial disposition: whether the current result supports CONTINUE, HOLD or RETRY for the next trial action.

What This Checklist Does Not Own

Pre-mount static inspection: mechanical, utility and machine-interface readiness should be resolved before powered trial work begins.
Stage approval authority: this page describes what to check during trial, not what each T0/T1/T2 stage is formally allowed to approve.
Detailed trial record fields: this checklist identifies evidence to capture but does not replace the dedicated process and sample record template.
Final mold acceptance: trial continuation is not the same as final tool approval or handover.
Formal validation: capability, PPAP, FAI, IQ/OQ/PQ or other customer-specific validation requirements are downstream decisions where applicable.
Full defect troubleshooting: this page records defect onset and location but does not replace a root-cause diagnostic guide.

Use the specialist owner when more detail is needed: formal stage-gate authority belongs in the T0/T1/T2 Mold Trial Approval Matrix , while detailed machine settings, sample IDs, CTQ results and adjustment history belong in the Injection Molding Trial Record Template .

Who Uses the Checklist During a Trial?

Tooling Engineer

Observes mold movement, shut-offs, release, ejection and tool-side findings under actual cycling conditions.

Process Engineer

Controls the sampling sequence and observes filling, V/P transfer, packing, cooling and process response.

Quality Engineer

Maintains cavity and sample traceability and records the inspection evidence required by the agreed trial plan.

Project / Sourcing Team

Reviews open findings, next-trial actions and whether the planned trial evidence has been delivered.

Working rule: use this page to decide what must be observed during a mold trial and what requires CONTINUE, HOLD or RETRY. Use separate owner documents for stage approval, detailed recordkeeping, validation and final mold acceptance.

Trial Start Inputs

What Must Be Ready Before Starting an Injection Mold Trial?

Once the mold is mounted, the trial should not begin with resin sampling until the team knows which tool revision is being tested, what the current trial stage is intended to learn, which machine and material conditions apply, and how samples and findings will be traced.

Trial start gate: confirm that no unresolved mounting blocker remains and that the trial objective, machine setup, material condition and evidence plan are sufficiently defined to make the resulting samples interpretable. Otherwise, running the mold may generate parts without producing useful engineering evidence.

Mold Identity and Current Revision

Confirm the mold number, cavity configuration, insert status and current engineering revision. The physical tool, applicable drawing and known engineering changes should describe the same build being tested.

Trial Stage and Engineering Objective

Define whether the run is intended to check first fill, short-shot progression, correction effectiveness, V/P transfer, packing and cooling response, repeatability or another project-specific trial objective.

Machine and Mold Setup

Confirm the intended injection molding machine, clamping and injection configuration, mold connections and other setup conditions needed for the planned trial. Record relevant starting conditions before process adjustments begin.

Resin and Material Condition

Identify the resin grade, lot or trial material where required, and confirm any preparation condition that affects the planned sampling. Material identity should remain linked to the resulting trial parts.

Sample and Cavity Traceability

Establish how trial stage, cavity ID, sample ID and relevant process condition will be linked. This is especially important when comparing short shots, cavity balance, corrected features or repeatability across multiple trial loops.

Observation and Measurement Plan

Decide which behaviors and sample characteristics need to be observed during the current run, including visible defects, part release, fill progression and project-defined dimensional or CTQ checks where applicable.

Do Not Start Resin Sampling If These Inputs Are Unresolved

Mold Revision Is Unclear

Do not generate trial evidence against an unidentified or inconsistent physical tool revision.

Trial Objective Is Undefined

A trial without a defined question makes later process and sample comparisons difficult to interpret.

Setup Condition Is Incomplete

Resolve machine, mold or required interface conditions that prevent the planned trial from being executed as intended.

Samples Cannot Be Traced

Establish cavity and sample identification before generating parts that will be compared across trial stages.

Scope boundary: this section defines the minimum inputs needed to start a useful mold trial. It does not establish final mold acceptance, formal validation requirements or the complete data structure of a trial report; those are controlled by their dedicated project documents.

T0 Trial Stage

T0 Mold Trial: Setup, Dry Cycle and First Fill Checks

T0 begins after the mold is mounted and the required pre-mount readiness checks are closed. The objective is to confirm how the tool behaves under actual machine control and during the first controlled resin injection before the team starts detailed fill-balance or process-development work.

T0 working principle: do not repeat the complete bench inspection or use T0 as final part approval. Confirm press-controlled movement, operating interfaces, first resin flow, mold opening and part release, and stop when a condition makes further sampling unsafe or technically unreliable.

T0.1

Establish the Starting Machine Condition

Record the machine and mold setup needed to interpret the first samples, including relevant starting temperatures, injection conditions, clamp setup and other project-defined baseline settings. The goal is traceability, not premature process optimization.

T0.2

Run the Powered Dry-Cycle Sequence

Observe mold opening and closing, ejector return, core pulls, slides, lifters, sensors and applicable sequence controls under actual press operation. Watch for unexpected timing, binding, incomplete return or machine-side interlock problems.

T0.3

Confirm Interfaces Under Operating Conditions

Verify that cooling, hydraulic, pneumatic, hot-runner and electrical systems used by the trial behave correctly after connection to the press and associated controllers. This is an operating check, not a repeat of the full pre-mount static inspection.

T0.4

Introduce Resin with a Controlled First Fill

Begin with the agreed startup sequence and observe whether resin enters the runner, gate and cavity as expected. Record severe hesitation, unexpected restriction, obvious imbalance, air-trap behavior or abnormal tool response before deeper sampling.

T0.5

Observe Opening, Release and Ejection

Once molded material is present, watch the actual opening sequence, part retention, side-action movement and ejection behavior. Thermal and resin-loaded conditions can expose sticking, drag or return problems that were not visible during bench checks.

T0.6

Record the First Trial Finding

Tie the first-shot observation to the relevant sample and trial condition. Any finding that affects safe cycling or meaningful sampling should be identified clearly enough to support the next CONTINUE, HOLD or RETRY decision.

Stop T0 and Investigate Before Continuing When:

Mechanical Sequence Is Abnormal

Stop for collision risk, incomplete return, binding or unexpected core, slide, lifter or ejector behavior.

Operating Interface Is Unstable

Investigate a utility, hot-runner, electrical, hydraulic or pneumatic condition that prevents controlled sampling.

Resin Flow Is Clearly Abnormal

Hold deeper sampling when the first fill shows severe restriction, unexpected blockage or another condition that makes the next step unreliable.

Part Release Is Unsafe or Unreliable

Do not continue normal cycling when the part or runner sticks, ejects unpredictably or creates a risk of tool damage.

T0 boundary: T0 establishes basic press-side tool function and first-fill evidence. Detailed fill progression and cavity-balance analysis belong to the following trial work, while repeatability, capability and final mold acceptance require later-stage evidence.

T1 Trial Stage

T1 Mold Trial: Fill Progression, First-Part Baseline and Early Defect Review

After basic T0 tool function is established, T1 should show how the cavity fills, how cavities compare and where the first repeatable part-quality concerns appear. Controlled short-shot sampling helps expose the filling pattern before packing and later process changes make that behavior more difficult to interpret.

T1 working principle: use a controlled sequence to understand filling behavior before deeper process development. The exact sequence should follow the project trial plan; do not rely on one universal short-shot percentage or treat one complete-looking part as proof that the mold is ready for later approval.

T1.1
Establish a Controlled Short-Shot Sequence

Generate a staged series of partially filled samples according to the trial plan. Keep the relevant filling condition identifiable for each step so the sequence can be compared without relying on a universal shot-volume percentage.
T1.2
Compare Flow-Front Progression

Review where the melt advances, hesitates, splits or converges. Note changes around ribs, bosses, thin transitions, long flow paths and other geometry that influences the observed filling pattern.
T1.3
Check Cavity-to-Cavity Fill Balance

For multi-cavity molds, compare relative fill progression between identified cavities at the same trial step. Record persistent leading or lagging cavities before packing makes the parts appear more similar.
T1.4
Record the Early Defect Baseline

Record hesitation, air-trap indications, burns, short-shot zones, weld-line locations, early flash or other visible conditions against the correct sample and cavity. Treat these as observations until supporting evidence confirms the root cause.
T1.5
Establish the First Complete-Part Baseline

After the fill progression has been reviewed, produce sufficiently complete samples to establish the first overall part baseline. Compare formation, visible conditions, cavity differences and release without treating the first complete part as proof of repeatability or final acceptance.

T1 boundary: T1 establishes the fill-progression, cavity-balance and first-part baseline needed for the next engineering review. Detailed V/P transfer, packing response, cooling development and correction verification move into T2, while repeatability, capability and final mold acceptance require later-stage evidence.

T2 Trial Stage

T2 Mold Trial: Verify Corrections, V/P Transfer, Packing and Cooling

T2 checks whether changes made after earlier sampling actually improve the mold result and whether V/P transfer, packing and cooling produce a more complete and technically interpretable part. The objective is controlled verification—not final process optimization or production approval.

T2 working principle: begin from the known T1 baseline, identify what changed and compare the updated result under controlled conditions. Avoid changing several unrelated variables at once when doing so would make the result difficult to interpret.

T2.1

Confirm What Changed Since T1

Identify the tooling correction, insert change, vent adjustment, gate-related change or planned process adjustment being evaluated. Keep the updated trial result traceable to the specific change being verified.

T2.2

Recheck Fill Progression After Correction

Compare the updated filling pattern with the previous T1 evidence. Check whether the intended correction improves hesitation, cavity-to-cavity balance, local filling restriction or another previously recorded flow-related finding.

T2.3

Review V/P Transfer Behavior

Observe whether velocity-to-pressure transfer occurs consistently at the selected point in the filling sequence. Record unstable transfer, abrupt part-weight response or visible sensitivity around the reviewed condition.

T2.4

Check Packing Response

Observe how the part responds as the agreed packing condition is established. Compare sink, flash, gate-area appearance, part weight and other project-relevant characteristics without treating one setting as a universal optimum.

T2.5

Review Cooling and Part Formation

Check whether the selected cooling condition supports consistent release and usable part formation. Record warpage, deformation, hot areas, sticking or ejection sensitivity that changes as the mold approaches its trial thermal condition.

T2.6

Compare the Updated Complete-Part Baseline

Compare corrected samples with the T1 baseline for overall part formation, visible defects, cavity differences and project-defined CTQ checks where applicable. Identify what improved and what still needs further verification.

What Changes from T1 to T2?

Review Area	T1 Focus	T2 Focus
Fill Pattern	Establish the initial fill-progression and cavity-balance baseline.	Verify whether the intended correction improves the known filling behavior.
V/P Transfer	Observe only as needed to establish the first-part baseline.	Review transfer consistency and its effect on the updated molded-part condition.
Packing	Avoid allowing packing to hide the initial filling pattern.	Observe part response as the planned packing condition is established or refined.
Cooling	Support controlled sampling and initial part release.	Observe how cooling affects part formation, release and known warpage or dimensional risks.

T2 Findings That Need Further Verification

Correction Effect Is Unclear

The updated result does not clearly improve the original finding, or too many simultaneous changes make the comparison inconclusive.

V/P Response Is Unstable

Transfer behavior changes unpredictably or produces inconsistent part response under otherwise comparable trial conditions.

Packing Creates a New Risk

A change that improves one feature introduces flash, stress, weight variation or another significant trial concern.

Thermal Behavior Is Still Moving

Cooling, release, warpage or other part behavior has not settled enough to support a meaningful later repeatability comparison.

T2 boundary: T2 verifies corrections and develops a more mature complete-part baseline under controlled V/P, packing and cooling conditions. It does not by itself prove long-run repeatability, process capability or final mold acceptance; those require later-stage evidence.

T3 / Post-T2 Repeatability Review

T3 / Post-T2 Review: Stable Run, Repeatability and CTQ Sampling

After the corrected mold condition has produced interpretable parts, the next review asks whether the selected setup can maintain consistent mold behavior and comparable samples over a defined run. Some projects call this T3, while others perform the same repeatability work within T2, a pilot trial or another customer-defined stage.

Repeatability review principle: establish a defined trial condition before comparing repeated samples. Run duration, sample quantity, measurement frequency and CTQ limits should follow the drawing, project requirements or validation plan. Stage naming alone should not determine whether the evidence is sufficient.

T3.1

Hold the Intended Trial Condition

Maintain the agreed machine and mold condition long enough for sample-to-sample comparison. Record intentional changes separately instead of mixing materially different settings into the same repeatability group.

T3.2

Watch Mold Behavior Across Repeated Cycles

Observe opening, side actions, ejection, release and thermal behavior across repeated cycles. Record drift, sticking or intermittent behavior that was not visible during isolated earlier samples.

T3.3

Compare Sample-to-Sample Consistency

Compare visible condition, part weight or other agreed trial indicators from samples produced under the same nominal setup. Look for meaningful drift or intermittent variation rather than one isolated acceptable shot.

T3.4

Compare Cavity-to-Cavity Behavior

For multi-cavity molds, preserve cavity identification and compare repeatable differences in filling, appearance, release or project-defined dimensions instead of averaging unlike cavity behavior together.

T3.5

Perform Project-Defined CTQ Sampling

Measure the dimensions, datum relationships, functional features or other CTQs required for the current review. Keep results traceable to the relevant sample, cavity and trial condition where required.

T3.6

Identify Remaining Repeatability Risks

Record behavior that changes across time, cavities or repeated cycles. Keep the observed variation separate from an assumed root cause until supporting evidence confirms the engineering diagnosis.

What Should Be Compared During the Repeatability Review?

Comparison	What to Watch	Why It Matters
Sample to Sample	Appearance, weight trend and selected dimensional or functional indicators.	Reveals drift or intermittent variation under a nominally unchanged condition.
Cavity to Cavity	Fill, appearance, release and selected CTQ differences between identified cavities.	Prevents a stable cavity from hiding another cavity with a repeatable imbalance.
Early Run to Later Run	Changes as the mold remains under repeated thermal and cycling conditions.	Helps expose time-dependent release, cooling, expansion or movement behavior.
CTQ Samples	Project-specified dimensions or functional characteristics tied to the correct samples and cavities.	Provides stage-appropriate evidence without turning the trial into a complete capability study.

Repeatability Findings That Need Further Review

Settings Keep Changing

Samples from materially different conditions are being combined into one repeatability comparison.

Mold Behavior Drifts

Release, cooling, movement or another mold condition changes enough over repeated cycles to affect the result.

Cavity Variation Persists

One or more cavities continue to show a repeatable difference that still requires engineering review.

CTQ Evidence Is Inconclusive

Required samples cannot be traced or the planned measurements do not yet support the intended review.

Repeatability boundary: this review can provide stable-run and CTQ evidence, but it does not by itself establish process capability or formal production validation. When the project requires broader capability or structured release evidence, continue with the Injection Mold Validation Guide .

Optional T4 Review

T4 Mold Trial: Optional Process-Boundary Review

When the project includes a T4-style review, selected process conditions can be moved away from the established nominal setting in a controlled manner to observe process sensitivity, defect onset and part response. The purpose is to understand trial behavior near the reviewed boundary—not to define one universal processing window for every mold, resin or machine.

T4 is not universal: some projects complete development without a separate T4 stage, while others use T4, pilot testing or another customer-defined step for process-boundary review. The selected variables, test range, sequence, review scope and decision criteria should follow the agreed project plan.

T4.1

Start from a Known Nominal Condition

Use the established trial condition as the reference before changing a selected variable. Keep the relevant mold, material and machine condition identifiable so later observations can be compared with a known baseline.

T4.2

Change Selected Variables Deliberately

Adjust only the variables defined by the trial plan and preserve enough control to interpret the result. Avoid uncontrolled multi-variable changes that make it unclear which adjustment caused the observed response.

T4.3

Record Where Visible Defects Begin

Note when flash, short shots, burn marks, sink, warpage, sticking or another visible condition becomes significant during the planned change. Keep the observation tied to the relevant cavity, sample and trial condition.

T4.4

Watch CTQ Sensitivity Where Required

For project-defined critical features, compare how selected dimensions, functional characteristics or assembly-sensitive features respond as the planned process condition changes. Use only the measurement scope required for the current review.

T4.5

Watch for Mold-Side Sensitivity Near the Boundary

Record whether release, thermal behavior, flash tendency or another relevant mold response becomes more sensitive as the selected process variable moves away from nominal. Focus on the change in behavior rather than repeating the full dynamic mold inspection.

T4.6

Return to Nominal and Confirm Recovery

Where required by the trial plan, return to the nominal condition and check whether mold and sample behavior return to the established baseline. Keep any residual drift or newly observed condition open for further review.

Example Variables to Observe During a T4 Boundary Review

Selected Variable	Controlled Review	What to Observe	Do Not Assume
Injection Speed	Compare planned lower, nominal and higher conditions where applicable.	Fill completion, hesitation, burn indication, weld-line position and other visible flow response.	One visible symptom proves a specific venting, gate or material root cause.
V/P Transfer	Shift the planned transfer condition within the defined review range.	Part-weight response, incomplete fill, flash tendency and sensitivity of selected features.	One transfer setting is universally correct across machines, resin lots or molds.
Packing Condition	Compare project-defined packing changes around the nominal condition.	Sink, flash, gate-area condition, part weight and selected CTQ response.	Higher packing automatically produces a more acceptable part.
Cooling Condition	Review planned cooling variation where it is relevant to the project.	Release, warpage, deformation, part handling and thermal sensitivity.	One cooling time or temperature range applies universally across tools and materials.

T4 boundary: this review can reveal process sensitivity and where visible defects begin under planned condition changes, but it is not a complete DOE, root-cause study or formal process validation. For deeper diagnosis of flash, short shots, burns, sink, warpage and other molding symptoms, use the Injection Molding Defects Troubleshooting Guide .

Cross-Stage Dynamic Checks

Dynamic Mold Performance Checks Across the Trial

Some mold behaviors should be monitored across multiple trial stages rather than assigned only to T0, T1, T2, T3 or T4. The important question is whether movement, release, thermal behavior, operating interfaces or cycle-to-cycle behavior changes under the actual trial condition enough to affect sample reliability.

Cross-stage working principle: record what changed, when it appeared, whether it repeated and which cavity, mechanism or trial condition was affected. A dynamic symptom should remain an observation until supporting evidence confirms its root cause.

What Dynamic Mold Behavior Should Be Watched Across the Trial?

Dynamic Area	What to Watch	Traceability	Needs Further Review When
Opening, Closing & Side Actions	Hesitation, abnormal noise, binding, incomplete return, delayed slide or lifter movement, or sequence interruption.	Trial stage, affected mechanism and relevant cycle condition.	The behavior repeats, worsens after heating or threatens controlled cycling.
Ejection & Part Release	Sticking, drag, deformation, ejector marks, runner retention or repeated manual assistance.	Cavity, sample, removal condition and affected feature.	Release varies across cavities or normal sampling depends on abnormal intervention.
Cooling & Thermal Behavior	Thermal drift, hot areas, changing warpage, release sensitivity or other cooling-related behavior over time.	Trial condition and relevant cavity, circuit or mold zone.	The changing thermal state prevents reliable comparison between samples.
Hot Runner & Operating Utilities	Heater-zone instability, alarms, leakage, pressure loss or intermittent hydraulic, pneumatic, cooling or electrical behavior.	Zone, circuit, connection or controlled interface.	The operating condition interrupts sampling or creates an unresolved mold-side concern.
Cycle-to-Cycle Drift	Changes in release, movement, reset behavior or other mold responses while the nominal trial settings remain unchanged.	Approximate cycle period, sample group and observed change.	Later samples are no longer directly comparable with the earlier trial baseline.

Route recurring or significant findings into the issue loop: the trial checklist should identify the observed condition and its traceability. Corrective action, ownership, re-check evidence and closure should then be managed in the Mold Trial Issue Tracking Sheet .

Scope boundary: this section summarizes dynamic mold behavior that can appear across multiple trial stages. It does not repeat the detailed T0–T4 checks, diagnose defect root causes, manage corrective actions or define final mold acceptance.

Trial Decision & Deliverables

When Should a Mold Trial Continue, Hold or Retry?

Each trial loop should end with a clear engineering disposition. The question is not whether the mold is already finally accepted, but whether the current evidence supports the next planned step, whether a blocker requires further investigation, or whether a correction must be verified through another controlled trial.

Decision principle: judge the current trial against its engineering objective and the project-defined review criteria. A complete-looking molded part should not override unsafe mold behavior, unstable sampling conditions, untraceable evidence or another unresolved finding that affects the reliability of the next decision.

CONTINUE

Proceed to the Planned Next Trial Action

Use CONTINUE when the current trial objective has been addressed, the resulting evidence is interpretable and no unresolved finding prevents the team from moving to the next planned review or trial activity.

Typical signal: the required observation is complete and any remaining item is documented without blocking the next step.

HOLD

Pause Advancement Until the Blocker Is Resolved

Use HOLD when mechanical behavior, utilities, part release, traceability or another significant finding makes further sampling unsafe, unreliable or difficult to interpret.

Typical signal: the unresolved condition must be clarified or corrected before meaningful sampling can continue.

RETRY

Repeat the Relevant Trial Check After Change

Use RETRY when a tooling correction or controlled process adjustment changes the condition being evaluated and the affected evidence must be regenerated for comparison.

Typical signal: the team can identify what changed and which previous observation needs to be repeated.

Minimum Deliverables from the Completed Trial Loop

This checklist does not need to reproduce every field in the detailed molding record. It should leave enough evidence for another engineer to understand what was tested, what was observed and what happens next.

Trial Stage & Objective Identify the trial loop and the engineering question being checked.

Relevant Setup Snapshot Preserve the mold, machine, material and process information needed to interpret the trial result.

Traceable Samples Keep the required cavity, sample and revision identification linked to the physical evidence.

Stage-Specific Evidence Retain the fill, correction, repeatability, CTQ or boundary evidence relevant to the current review.

Open Findings Identify unresolved mold, process, sample or evidence conditions that still require follow-up.

Disposition & Next Action Record CONTINUE, HOLD or RETRY together with the next planned engineering action.

Trial disposition is not final mold acceptance: CONTINUE means only that the current evidence supports the next planned engineering step. Final tool approval, conditional acceptance, handover requirements and project-level release criteria belong in the Injection Mold Acceptance Criteria .

Mold Trial FAQ

Injection Mold Trial Checklist FAQ

These questions clarify the practical use of a T0–T4 mold trial checklist, including short-shot review, repeatability, optional T4 testing and the difference between trial progression and final mold acceptance.

What is a T0 mold trial in injection molding?

T0 is the first controlled press-side trial after the mold has been mounted and the required pre-mount conditions are closed. It typically checks powered mold movement, operating interfaces, first resin flow, mold opening and part release. T0 is intended to establish basic tool function and first-fill evidence, not to prove final part quality or production readiness.

Why is a short-shot sequence useful during T1?

A controlled short-shot sequence shows how the melt front advances through the cavity before packing pressure can hide the initial filling pattern. Engineers can compare hesitation, flow-front progression, cavity-to-cavity balance and early defect locations. The sequence should follow the project trial plan rather than a universal shot-volume percentage.

What evidence shows that a T3 mold trial is repeatable?

Repeatability requires comparable samples produced under a defined trial condition, not one acceptable shot. Useful evidence may include repeated-cycle mold behavior, cavity and sample traceability, part-weight trend, visible defect consistency and project-defined CTQ measurements where required. The run duration, sample quantity and measurement frequency should follow the applicable project or validation plan.

Is a T4 process-boundary trial required for every injection mold?

No. A separate T4 stage is not universal. Some projects use T4 to examine robustness, process sensitivity or defect onset around an established nominal condition, while others complete development under a different stage structure. The need for T4, variables to be changed and review range should follow the agreed project plan.

When should a mold trial be held or repeated?

Use HOLD when an unresolved condition makes continued sampling unsafe, technically unreliable or difficult to interpret. Use RETRY after a tooling correction or controlled process change when the affected evidence must be regenerated. Examples include unstable mold movement, unreliable release, unresolved fill behavior, missing traceability or a correction that still requires verification.

Does a successful mold trial mean the mold is finally accepted?

No. A successful trial means the evidence supports the intended trial-stage decision or next engineering step. Final mold acceptance may also require project-defined dimensional, functional, documentation, open-item closure, validation or handover evidence. Therefore, a CONTINUE disposition in this checklist should not be interpreted as final tool approval.

FAQ boundary: this page answers how to execute and review a mold trial. Detailed trial record fields, corrective-action management, formal validation, capability studies and final mold acceptance remain separate project activities.

Mold Trial Engineering Support

Need an Engineering Review Before Your Next Mold Trial?

If an injection mold is between trial loops, send the current engineering information to SPI for review. We can help examine trial observations, sample evidence and unresolved mold or molding concerns before the next sampling run, so the team knows which questions should be verified next.

Useful Information to Send

Current Part & Mold Data

3D CAD, 2D drawing and the current mold or insert revision where relevant.

Latest Trial Conditions

The latest molding condition record and a short description of the trial objective.

Sample & Defect Evidence

Cavity-tagged sample photos, short-shot evidence and marked defect locations where available.

Open Issues

Current tooling or process concerns, previous corrections and the questions that still require verification.

Trial Evidence Review Check whether the available samples and observations clearly support the next engineering discussion.

Mold / Process Risk Separation Review whether an observed problem should first be investigated from the tool, molding condition or part-design side.

Next-Trial Priorities Identify which open questions should be verified during the next controlled sampling loop.

Request a Mold Trial Review →

Review scope: a document- and evidence-based engineering review can help identify questions and priorities before the next trial. Final trial disposition still depends on verification of the actual mold, machine, material and molded samples.