CNC Machining & Injection Molding — DFM/Moldflow Support, CMM Inspection, Prototype to Production Solutions.
Input Freeze → DFM & Tooling Review → T0/T1 Acceptance + Evidence Fields
Mandatory checklist for 2D/3D master data, resin specs, and cosmetic zones prior to steel cut.
Technical validation for draft, gating, venting, and cooling with owner/due date tracking.
Defined criteria for T0 function vs T1 quality, including FAI/PPAP evidence requirements.
Access the checklist in the format that best fits your workflow. All versions include persistent Doc IDs and Evidence Fields for engineering traceability.
Rule: No tool design release if any item is marked NG. Verifies 2D/3D master data, GD&T, Resin grade, and Cosmetic Maps. Prevents "guessing" in the toolroom.
The Design Freeze phase. Documents technical alignment on Gating, Parting Lines, Venting maps, and Cooling circuit coverage. Requires physical evidence (screenshots/simulations).
The Release Gate. Establishes T0 (Functional) vs T1 (Quality) standards. Includes placeholders for FAI balloon drawings and PPAP-level evidence requirements.
This template is built on industry-standard SPI/ANSI guidelines, but your shop floor needs specific tolerances. We recommend two quick edits after downloading:
Successful injection molding requires cross-functional discipline. This checklist acts as the "Engineering Handshake" between Manufacturing, Tooling, and Quality teams to prevent late-stage rework.
Kickoff Alignment: Use Sheet 1 (Input Freeze) to ensure the toolroom has 100% of the data needed—GD&T, CTQs, and resin grades—before steel cut. Eliminate "design assumptions" that lead to scrap.
Design Freeze & Evidence: Use Sheet 2 (DFM) to audit gating, venting, and cooling circuit coverage. Ensure the supplier provides physical evidence (simulations/CAD overlays) for every critical shut-off.
FAI/PPAP Release: Use Sheet 3 (Acceptance) to define "Release Readiness." Verify that T0/T1 data meets dimensional Cpk targets and that all FAI balloon drawings are indexed correctly.
This template is designed to follow the standard NPI (New Product Introduction) path. Mapping your checkpoints to these gates ensures no critical task is bypassed during the rush to SOP.
*The Checklist Template provides specific "Go/No-Go" gateways at the Design Freeze and T1 Acceptance stages.
Open Sheet 1. Audit the master data immediately. If the 2D GD&T, resin grade, or cosmetic map is missing, mark the item NG and stop the review. Do not allow tooling design to proceed on assumptions; this is where most $10k+ rework costs begin.
Go to Sheet 2. Walk through the gating, venting, and ejection layout. For every critical shut-off or high-risk weld line zone, require the supplier to attach physical evidence (screenshots or simulation results). Trust the data, not the "we will handle it" promise.
Transition to Sheet 3. Define exactly what a "Pass" looks like for the first trial. Assign specific Owners and Due Dates for the FAI (First Article Inspection) package. This ensures the SQE (Supplier Quality Engineer) and Tooling Engineer are aligned on delivery expectations before the press starts.
The checklist serves as your Single Source of Truth. Monitor the "NG" log. Tooling steel should not be cut until all Sheet 1 and Sheet 2 "Critical" items are closed. Use the Doc ID in the checklist to link to the final approved CAD revision.
A checked box is an opinion; a screenshot is a fact. Ensure these four evidence types are attached to your review log:
A 2D/3D overlay showing exactly where the mold halves meet relative to cosmetic surfaces and critical dimensions.
Simulation results or manual sketches identifying weld line concentrations near screw bosses or high-stress zones.
A visual map identifying gas evacuation points at the absolute last point of fill to prevent diesel burns.
Example of a ballooned drawing paired with a trend chart showing dimensional stability (Cpk) for critical-to-quality features.
Before mold design release, you must freeze the 2D drawing with GD&T and CTQs, the 3D model revision, the exact resin grade, cosmetic/texture requirements, and acceptance criteria for key defects. Missing inputs should be marked NG and resolved first to avoid costly steel rework or failed trials.
The "Input Freeze" is the most critical quality gate in the tooling lifecycle. Proceeding with mold design while these parameters are "TBD" (To Be Determined) creates an immediate risk of unrecoverable tooling scrap.
Establish the measurement strategy early. Limit Critical-to-Quality (CTQ) features to the most essential dimensions to ensure focus during FAI.
Verify that the mold shop is working off the latest engineering release. Any "verbal" design changes not reflected in the CAD are a major failure point.
Different resin grades (e.g., PC vs. PC/ABS) have drastically different shrink rates. A 0.001 in/in error in shrink assumption can ruin a high-precision tool.
Define visual requirements. High-texture areas require extra draft (typically 1.5° per 0.001" depth) which must be designed into the tool from day one.
Does the annual volume justify a hot runner? Is the steel class (Class 101 vs. 103) appropriate for the expected life of the program?
Align on documentation early. If a Level 3 PPAP is required, the data collection for the control plan and FMEA must start during design.
Agree on what is acceptable. Where are weld lines allowed? How much gate vestige is permissible? Define this before the gate is cut into the steel.
| Input Item | Why It Matters | If Missing, What Breaks? |
|---|---|---|
| Resin Grade | Dictates steel dimensions based on specific shrink rates. | Tooling becomes scrap if the resin is changed post-steel cut; dimensions won't hit. |
| CTQ List | Focuses the toolroom on critical tolerances and datums. | CMM measurements become meaningless; FAI/PPAP rejection due to wrong measurement points. |
| Cosmetic Map | Informs gate and parting line placement to hide defects. | Weld lines or gate scars appear in high-visibility areas; customer rejects parts on aesthetics. |
| Draft/Texture | Ensures parts release from the mold without scuffing. | Texture drag or part sticking; requiring expensive EDM/re-polishing and steel-added rework. |
This is the critical "Engineering Handshake" phase. The items below are the most common points of debate in a design review—resolving these now prevents the $5,000+ per-loop cost of T0/T1 rework.
Tooling concept alignment is the final technical agreement before steel cut. It requires formal sign-off on gate locations, parting line (PL) overlays, and weld line risk zones. This ensures both the molder and the customer agree on the physical "witness marks" that will appear on the final molded part.
The gate is the part’s "umbilical cord." You must agree on the gate vestige (the remaining scar). For high-cosmetic A-surfaces, use sub-gates or valve gates to hide the entry. If using a direct sprue, ensure the location allows for easy manual or robotic trimming without damaging the part geometry.
Map out the Parting Line (PL). On cosmetic parts, the PL should follow a natural edge or a "hidden" break. If the PL must cross an A-surface, a PL Overlay is mandatory to show the step-off or flash risk. Never assume a supplier knows which side is the "visual" side.
Weld lines are structural and cosmetic weak points. Using flow simulation, identify where the melt fronts meet. Pro-Tip: Forbid weld lines near screw bosses or snap-fits where mechanical stress is highest. Sign off on a "Weld Line Map" before cutting gates.
Identify the "End-of-Fill" locations. These are the primary venting zones. If a rib or boss creates a blind pocket, it acts as a "gas trap." Ensure the tooling plan includes inserts or porous steel in these areas to prevent diesel burns and short shots.
How the part leaves the mold is as important as how it enters. Review the ejector pin layout. Excessive force on a hot part causes "ejector blush" or stress whitening. Align on pin locations—ensure they push on ribs or thick sections, never on thin cosmetic walls.
Do not proceed to steel cut without a Parting Line Overlay (PDF) and a Gate/Weld-Line Sketch (Annotated 3D). These two documents are your primary insurance against cosmetic disputes at T1.
Cooling is the primary driver of dimensional stability and cycle time. It requires verifying hotspots in thick cross-sections, auditing baffles and bubblers, and balancing cooling-time targets against warpage risks. For high-stability parts, copper alloy inserts or high-thermal conductivity steel are often required to manage heat in deep cores.
Engineering Fact: In a typical injection molding cycle, 80% of the cycle time is spent on cooling. Optimizing your cooling layout in the DFM phase is the single most effective way to reduce piece-part cost and eliminate dimensional drift.
T0 is a functional milestone verifying that the mold fills, vents, and ejects safely without mechanical damage. T1 is a quality and stability milestone, requiring dimensional convergence of CTQs, cosmetic sign-off, and a documented process window that supports PPAP or FAI-style release.
| Metric | T0 (Functional Trial) | T1 (Quality Validation) |
|---|---|---|
| Primary Objective | Does the mold function mechanically? | Can the mold repeatably produce in-spec parts? |
| Required Output | Dry cycle log, flash/burn map, T0 shot samples. | Full FAI report, $C_{pk}$ data (N=30), Process Window Study. |
| Common Misconception | "The parts look okay, so the mold is finished." | "Just check the dimensions and start shipping." |
Don't rely on "Golden Samples." A practical baseline for T1 acceptance is a continuous run of 30 to 50 stable shots once the tool reaches thermal equilibrium. This provides enough data to calculate initial $C_{pk}$ and identifies drift issues that T0's 5-shot samples will never catch.
The Failure: The customer expects a "seamless" part, but the molder places the parting line across a visual A-surface because it was easier for the toolroom. The Fix: Our checklist mandates a Parting Line & Gate Overlay sign-off before steel is cut. If the location isn't on the approved drawing, the rework cost is on the supplier.
The Failure: A VDI-27 texture is applied to a wall with only 1.0° of draft. During T0, the part scuffs and sticks, requiring the tool to be pulled for EDM rework. The Fix: The DFM sheet enforces the "Texture Draft Rule": adding $1.5^\circ$ per $0.001"$ of texture depth. No design release happens until the CAD matches the texture spec.
The Failure: The supplier measures a diameter with calipers; the customer uses a CMM with a specific datum scheme. The results don't match, and PPAP is rejected. The Fix: Sheet 1 (Input Freeze) requires Measurement Method Alignment. You agree on the "How" (CMM/Vision/Gage) and the "Where" (Datums) before the first trial.
The Failure: SOP is one week away, and the team realizes the supplier hasn't started the Capability Study or the Control Plan. The Fix: The PPAP Level Alignment happens at kickoff. The checklist tracks evidence requirements (FAI ballooning, Process Logs) as early as T0, ensuring docs are ready when the parts are.
The Failure: An asymmetric part warps 2.0mm out of spec because the core was significantly hotter than the cavity. The Fix: The Thermal Risk Map in the DFM phase identifies cooling imbalances. We mandate a review of the cooling layout for GF (Glass Filled) resins to predict and counteract orientation-driven warp.
Experience is easy to claim; data is harder to fake. Use this checklist during your next supplier audit to distinguish between a "shop that just cuts steel" and a partner that understands Scientific Molding.
Don't accept a simple "Yes/No" DFM. Look for:
Check if their trial reports include:
Verify their measurement strategy:
The document should clearly state:
If a supplier responds with these "Design Deflections," proceed with caution:
Need an independent "second set of eyes" on your project? Upload your STEP + 2D drawing (NDA available). Our engineers will provide a 1-page proposal covering gate location, parting line placement, and weld line risk zones.
Upload Drawing for Review*No commitment. Just technical feedback to help you avoid rework.
Before mold design release, you must freeze the 2D drawing with GD&T, 3D model revision, resin grade (including shrink rates), cosmetic/texture zones, and cavitation requirements. These "hard gates" prevent expensive steel rework and ensure the tool is built to the correct functional and aesthetic specifications from day one.
DFM (Design for Manufacturing) focuses on the part's manufacturability, such as wall thickness and draft. A Tooling Design Review audits the mold's mechanical construction, including gate type, parting line overlays, cooling circuit efficiency, and ejection layout. DFM is part-centric; Tooling Review is tool-centric and requires sign-off.
[Image of the difference between DFM and tooling design review]T0 acceptance confirms safe mechanical function (filling, venting, and ejection). T1 acceptance requires dimensional convergence (all CTQs in spec), cosmetic sign-off against the DFM map, and a documented stable process window. A 30-shot continuous run at thermal equilibrium is the standard for T1 stability verification.
[Image of injection molding T0/T1 acceptance checklist]Define Critical-to-Quality (CTQ) dimensions on a ballooned 2D drawing, limiting them to $\le 10$ high-impact features. For each CTQ, specify the measurement method (CMM, Vision, or Gage) and the datum scheme to ensure alignment between supplier inspection and customer incoming quality control.
[Image of CTQs and measurement methods for injection molding]Textured surfaces require significantly more draft than smooth walls. Use a baseline of $1.5^\circ$ of draft per $0.001"$ ($0.025\text{mm}$) of texture depth. Failure to provide adequate draft on SPI or VDI textured surfaces leads to texture drag, scuffing, and permanent damage during part release.
[Image of textured surfaces and draft angles for injection molding]