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Mold Run-Off / Tryout Checklist for Injection Molding (Downloadable Engineering Template)

This comprehensive run-off toolkit provides a standardized framework for validating new tooling before production release. Engineered for process engineers, mold makers, and quality departments, it bridges the communication gap between the toolroom and the press with a multi-stage checklist (T0–T4) and a centralized issue log.

Direct Download: Standard Engineering Template

Download Checklist (HTML) Excel (.xlsx) Google Sheets

“Use as-is. Replace example thresholds with your internal standards.”

What This Checklist Covers (and Why T0–T4 Prevents Rework)

A professional mold run-off is more than just "making parts." This checklist follows a Scientific Molding methodology, breaking the trial into five distinct gateways to ensure every failure mode is identified before the tool leaves the shop floor.

T0: Pre-Run

Setup & Safety

Verification of mold height, water circuit flow, ejector return, and safety interlocks before the first shot.

T1: Short Shot

Fill Balance

Determining the 95-98% fill position (without pack/hold) to verify cavity-to-cavity balance and gating health.

T2: Near-Full

V-to-P Transfer

Establishing the switchover point and initial pack/hold profile to achieve a visually complete part.

T3: Stable Window

Repeatability

Running the tool at thermal equilibrium to confirm CPK, cycle time, and dimensional stability over N shots.

T4: Boundary

Process Limits

Stress-testing the process window (high/low pack & temp) to record the onset of defects like flash or sink.

Single Source of Truth: Eliminating Duplicate Notes

Communication breakdown between the toolroom and the molding floor is the #1 cause of rework. Our checklist utilizes Unique ID Issue Logging—every NG result is assigned a persistent ID that follows the mold through repair, re-try, and final sign-off.

Unique Issue IDs Centralized Issue Log Revision Control Evidence

Mold Assembly Verification Checklist (A-Series)

Before a tool ever touches the press, it must pass the A-Series Static Audit. These checks ensure that the physical build matches the design intent and that all mechanical systems are lubricated, cleared, and safe for dynamic movement.

Mechanical & Shutoffs

Parting Line Spotting: Verify >90% contact using bluing agent.
Slide/Lifter Travel: Manual stroke check for binding or "slop."
Mechanical Interlocks: Confirm zero-interference during plate movement.
Leader Pins/Bushings: Check for scoring or lack of lubrication.

Cooling & Hydraulic

Circuit Continuity: Verify "IN" and "OUT" labels match flow diagrams.
Pressure Test: Static hold at 80-100 PSI for 15 minutes (Zero Drop).
Baffles/Bubblers: Physical depth check to ensure proper seated height.
Hydraulic Sync: (If applicable) Verify cylinder stroke limits.

Ejection & Safety

Ejector Return: Confirm pins are flush or 0.05mm below parting line.
Return Pins: Verify positive contact with the back plate.
Safety Switches: Ohm-check for normally open/closed continuity.
Locating Ring: Verify concentricity and screw torque.

Hot Runner Electrical

Zone Mapping: Match controller IDs to physical drop locations.
Resistance Check: Verify Ohms per heater specification.
Thermocouple Polarity: Verify Type J/K consistency to prevent runaways.
Grounding: Continuity check to mold base.

Data Recording Protocol

Every checklist item must be recorded with objective evidence. Avoid "Checked" notations; use data-driven values.

[Status: OK / NG / NA] [Measured Value (e.g., 82 PSI)] [Evidence: Photo ID / Log #] [Technician Signature] [Timestamp]

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Critical Assembly Misses (Trial Rework Drivers)

Shutoff Contact Failure: Insufficient "crush" or spotting at complex parting line intersections leads to immediate flash at T0, often misdiagnosed as clamping pressure issues.

Cross-Flow Cooling: Incorrect O-ring placement or missing baffles can cause "short-circuiting" where water bypasses the cavity, leading to localized hot spots.

Ejector Binding: Thermal expansion isn't always accounted for in long, slender pins. A pin that moves freely at 20°C may seize at a mold temperature of 80°C if clearances are too tight.

Trial Dynamic Confirmation Checklist (T-Series)

Once the mold is in the press, the T-Series Dynamic Checklist shifts focus from the physical build to real-world performance. This phase validates the "Scientific Molding" parameters and ensures the tool maintains equilibrium over high-volume production cycles.

Cooling Performance Confirmation

Verify that the thermal management system controls the process rather than restricting it.

Delta T Recording: Measure temperature difference between water "IN" and "OUT" (Target <2°C for precision parts).
Thermal Equilibrium: Confirm mold surface temperature stabilizes after N shots using an IR probe.
Hot Spot Identification: Scan deep ribs and cores for heat build-up that exceeds nominal targets.

Ejection & Release Behavior

Confirm clean part release without secondary damage or stress.

Release Smoothness: Note any "hesitation" or audible sticking during the ejection stroke.
Witness Mark Audit: Inspect part for stress whitening or excessive pin marks.
Automatic Drop: Confirm parts fall clear of the mold and don't hang on slides or lifters.

Flash Location Mapping

Identify exactly where the seal fails under injection pressure.

Category 1: Parting Line. Flash around the primary profile.
Category 2: Shutoff. Flash at complex interlocking geometries.
Category 3: Vent. Flash occurring in gas evacuation channels (over-venting).

Dimensional Stability (N=30)

Verify the process is capable of repeatable precision.

Short-Term Capability: Measure Critical Dimensions (CDs) across 30 consecutive stable shots.
Shot-to-Shot Weight: Log part weight variation (Target <0.5% deviation).
Warp Analysis: Confirm flatness/roundness remains within tolerance at thermal equilibrium.

Cycle Time Breakdown Recording

A critical step to confirm the commercial feasibility of the tool. Record actuals against the original DFM quote.

Phase	Target (sec)	Actual (sec)	Observations / Bottlenecks
Fill Time	---	---	Check for flow hesitation
Pack/Hold Time	---	---	Determined by Gate Freeze study
Cooling Time	---	---	The primary driver of cycle efficiency
Mold Open/Close	---	---	Dry cycle speed of the press
Total Cycle	---	---	---

Acceptance Criteria Examples (Baseline Reference)

IMPORTANT: The following values are technical examples intended to serve as starting points for your run-off plan. Final acceptance criteria must be defined by your specific industry standards (e.g., Medical ISO 13485 vs. Automotive IATF 16949), resin grade, and part geometry.

1. Thermal Performance ($\Delta T$)

Documenting cooling efficiency ensures cycle repeatability and warp control.

Parameter	Suggested Target
Coolant In/Out Differential	$\Delta T < 2^\circ\text{C}$ ($4^\circ\text{F}$)
Cavity-to-Cavity Surface Delta	$\pm 3^\circ\text{C}$
Time to Thermal Equilibrium	Recorded @ Shot Count

2. Repeatability Window ($N=10\text{--}30$)

Verification of process capability over a continuous stable run.

Metric	Acceptance Baseline
Shot Weight Deviation ($N=30$)	< 0.5%
Critical Dim (CD) Cpk ($N=30$)	> 1.33
Auto-Cycle Stability	Zero manual intervention

3. "Defect Onset" Documentation

True mold validation involves finding the edges of the cliff. Boundary testing (T4) documents the exact point where process variables cause failure, establishing the Safety Buffer for production.

Flash Onset

Record the minimum Pack/Hold pressure at which parting line flash occurs. Target: $> 10\%$ above nominal process.

Short Shot Point

Record the minimum Fill Pressure / Velocity at which a non-fill occurs. Defines lower limit of the window.

Recovery Baseline

Note the time required to return to "In-Spec" production after a 15-minute emergency stop (thermal soak test).

How to Use the Issue Log (Single Source of Truth)

The Issue Log is the nervous system of the run-off. It prevents the "Friday Afternoon" communication gap where critical trial failures are lost in emails or verbal handovers. To maintain integrity, follow these two mandatory protocols:

Protocol A

One NG = One Permanent Issue ID

Every No-Good (NG) result discovered in the checklist must be assigned a unique, sequential ID (e.g., #ISS-001). This ID acts as a digital leash, following the defect through toolroom repair, re-polishing, or process adjustment until final closure.

Protocol B

Re-checks Update, Never Duplicate

If a fix fails during T2, do not create #ISS-015. Instead, update the status and history of #ISS-001. This preserves the Root Cause History, allowing engineers to identify if a fix was ineffective or if a new variable was introduced.

What "Good" Evidence Looks Like

Data without context is noise. Every Issue ID must be backed by three pillars of evidence:

1. Physical Context

High-Res Photos: Macro shots of the defect + Wide shot of the part orientation.
Cavity ID: Specific cavity number where the defect occurred.
Physical Samples: Retain the "Fail Sample" with the Issue ID written on the part.

2. Parameter Snapshot

Process Sheet: Screenshot of the machine settings at the time of failure.
Scientific Data: Melt temp, fill time, and pack/hold profile records.
Cycle Time: Actual vs. Target breakdown at the time of NG.

3. Correction Plan

Engineering Hypothesis: Why we believe the defect occurred (e.g., "Insufficient venting").
Action Owner: The specific toolmaker or engineer responsible for the fix.
Target T-Stage: Which trial stage (T2, T3, etc.) the fix will be verified.

Downloadable Engineering Templates

Access our master mold run-off toolkit in the format that best fits your workflow. From live collaborative sheets to printable shop-floor documents, ensure your team captures every critical data point.

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HTML Template

Browser-ready interactive checklist for digital entry on tablets or mobile devices.

Access Web Version

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Excel / Google Sheet

Editable spreadsheet with automatic issue ID generation and data analysis charts.

Download .XLSX

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Printable PDF

High-resolution format optimized for manual floor inspections and physical tool binders.

Download PDF

Document ID: SI-TR-CHECK-2026 Version: Rev 4.2 Last Updated: March 03, 2026

FAQ: Injection Molding Run-Off & Tryout

What’s the difference between mold tryout and run-off?

A mold tryout focuses on basic tool functionality (T0-T1), verifying that the tool opens, closes, and ejects safely. A mold run-off is a performance verification (T3-T4) that confirms the tool can produce repeatable, in-spec parts at the quoted cycle time under production-floor conditions.

What is a short shot study and why do it?

A short shot study involves filling the mold to 95-98% without pack/hold pressure. It is used to verify cavity-to-cavity balance and identify flow hesitation or gas traps. If cavities fill unevenly at this stage, dimensional stability will be impossible to achieve in production.

How do you document flash location correctly?

Flash should be mapped using standard categories: Parting Line, Shutoff, or Vent. Document the location using a "Clock Face" (e.g., flash at 3 o'clock) or a grid system. Specify if the flash is due to steel mismatch (tooling) or excessive injection pressure (process).

What should you measure to confirm cooling is the cycle driver?

Measure the Delta T (temperature difference) between water "In" and "Out" (target < 2°C) and the part's surface temperature at ejection. Record a cycle time breakdown; if increasing cooling time directly improves part quality or ejection, cooling is the primary cycle driver.

How many shots are enough to confirm stability?

Industry standard is typically a continuous run of 30 stable shots once thermal equilibrium is reached. For high-precision or automotive parts, a longer 4-to-8 hour run-off may be required to verify long-term stability, Cpk values (>1.33), and tool-room maintenance intervals.

What is V-to-P transfer and how does it affect weight repeatability?

V-to-P (Velocity-to-Pressure) transfer is the point where the machine switches from filling to packing. A consistent transfer point is critical for shot-to-shot weight repeatability. If the transfer happens too late (overfilling), it causes flash; too early, and part density varies.

Need a Second Set of Eyes on Your Run-Off Results?

Tooling trials are high-pressure environments where subtle symptoms often mask deeper mechanical risks. If your current T1 or T2 results are inconsistent, our engineering team can provide a neutral, technical review of your data.

Cooling Circuit Risks: Identification of potential hot spot root causes and thermal imbalance.
Ejection Witness Mitigation: Practical ideas to reduce stress whitening and pin marks on cosmetic surfaces.
Flash Root-Cause Direction: Determining if flash is a shutoff/steel issue or clamp/process sensitivity.
Documentation Quality Audit: Ensuring your process window and T-stage data are production-ready.

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