CNC Machining & Injection Molding — DFM/Moldflow Support, CMM Inspection, Prototype to Production Solutions.
Align customer requirements, mold design, and production teams from day one. Standardize technical inputs to eliminate costly engineering rework and streamline final tool acceptance.
A Mold Specification Sheet is a controlled technical document that defines a mold's configuration and measurable acceptance criteria. It aligns stakeholders—customer, designer, and toolmaker—on cavitation, gating, steels, finishes, and press constraints to ensure tool build readiness and successful run-off validation during final tool acceptance.
Identifies who is responsible for the data—Design, Customer, or the Toolmaker. Eliminates "I thought you were providing that" errors.
Status tags: Pending, Reviewed, Frozen, or N/A. Steel should never be ordered until critical specs are marked "Frozen".
The core of the document. Defines the measurable result (e.g., Cpk > 1.33 or leak-free at 80 PSI) required for tool sign-off.
A professional mold build starts with a frozen specification. Use this 13-point checklist to audit your current spec sheet or fill in our editable template. These fields represent the minimum data required to align global tooling standards.
| Section Block | Status | What This Prevents / Engineering Goal |
|---|---|---|
| Steel & Heat Treat | REQUIRED | Prevents premature wear or catastrophic tool failure under press tonnage. |
| Press Constraints | REQUIRED | Eliminates tie-bar mismatch, daylight issues, or ejector pattern conflicts. |
| Venting Map | REQUIRED | Critical for eliminating gas burns and ensuring full part filling at end-of-fill. |
| Texture Direction | OPTIONAL* | Required for deep-draw parts to prevent drag marks on textured faces. |
| Spare Parts List | OPTIONAL | Recommended for high-cavitation/multi-million shot production tools. |
Filling out a spec sheet is an exercise in risk management. Below are the engineering rationales for the fields that most frequently impact tool performance and part cost.
Cavitation isn't just about volume; it’s about rheological balance. For high-precision parts, a balanced "H" layout is superior to a radial layout. Consider the inspection burden: 32 cavities mean 32 FAI reports.
Choosing between Sub-gating (automatic de-gating) and Valve-gating (high cosmetic, zero waste) affects both cycle time and part price. Specify the maximum allowable vestige (e.g., <0.15mm) to avoid post-molding trimming disputes.
Don't just specify "Steel." Map it to the resin. For Glass-Filled (GF) resins, abrasive wear is the risk (use H13 or D2). For PVC or Flame Retardant (FR) resins, corrosive outgassing is the risk (use S136 or 420SS).
Specify the target Rockwell C (HRC) range, not just a single number. Demand a Heat Treat Certification and specify that hardness must be verified at three points on the actual insert, not just the test coupon.
Avoid mismatch by specifying the exact standard. SPI is for polished/diamond finishes (A-1, B-2). VDI 3400 is for EDM-textured finishes. Specify if the texture must follow a specific grain direction for part release.
Specify separate circuits for the Core and Cavity to allow for differential temperature control (essential for warpage control). All circuits should be pressure tested at 80 PSI for 30 minutes with zero ΔP.
Verify the mold's horizontal vs. vertical dimensions against the press tie-bar spacing. Specify the ejector rod pattern (Center only vs. Standard 5-point) to ensure the mold can actually run in the target machine.
Not sure if your steel hardness or cooling layout is optimized for your cycle time targets? Get an expert second opinion before steel is cut.
Request a 1-Page Spec Sanity Check →Most tool-build delays aren't caused by machining errors, but by "Spec Drift"—ambiguity in the initial documentation that leads to expensive T1 rework.
A mold run-off is a final production validation test conducted before tool shipment. It verifies that the mold consistently meets all mechanical, functional, and dimensional specifications under production conditions. Successful run-off data serves as the legal and technical baseline for tool sign-off and final payment.
Standardize your tool acceptance by adding this clause to your Mold Specification Sheet:
MOLD ACCEPTANCE CRITERIA:
1. CONTINUOUS PRODUCTION: 4 HOURS MINIMUM WITH NO MECHANICAL ALARMS.
2. DIMENSIONAL: CPK > 1.33 ON CTQ DIMENSIONS; 100% PASS ON FAI.
3. COSMETIC: MATCH BOUNDARY SAMPLE #REF-123; ZERO VISIBLE FLASH.
4. COOLING: 80 PSI LEAK TEST (30 MIN); ΔT < 3°C BETWEEN CIRCUITS.
5. CYCLE TIME: TARGET 18S; MAXIMUM ALLOWABLE 19S.
6. DOCUMENTATION: 3D CAD UPDATED TO STEEL; HT CERTS PROVIDED.
In the event that the mold fails to meet the defined run-off criteria, a Root Cause Analysis (RCA) is initiated. Non-conformances are documented in a Change Control Note. A mandatory re-tryout is required after corrective actions (e.g., steel adjustment or cooling optimization) are completed. Final tool shipment is suspended until all "Red" status items are verified and signed off by the engineering lead.
A mold is a high-value capital asset. To ensure long-term maintenance and internal quality compliance, the following "as-built" documentation package is mandatory before final tool sign-off.
Before you finalize Rev 1.0 and release the steel order, our engineering team provides a high-level technical audit to ensure your specification aligns with production reality and press constraints.
Yes. While prototype (Bridge) tools use aluminum or pre-hardened steel, a spec sheet remains mandatory to define gating, parting line expectations, and ejector pin locations. Without a spec sheet, prototypes often lack the cooling or venting required to produce parts that accurately represent production-level quality or cycle times.
SPI finish standards (A, B, C) define diamond-polished and grit-polished surfaces, primarily for high-gloss or clear parts. VDI 3400 is an EDM-textured finish standard (12-45) that defines the surface roughness (Ra) of spark-eroded textures. SPI finishes require manual polishing, while VDI textures are achieved through electrical discharge machining or chemical etching.
Mold life (Class 101-105) is determined by steel selection and heat-treatment. Specify Class 101 (1M+ shots) using hardened H13/S136 steel (@48-52 HRC). Class 103 (100k-500k shots) uses pre-hardened P20 steel. Always document the intended annual volume in the spec sheet to ensure the builder selects the appropriate mold base and slide materials.
Before releasing a steel order (Rev 1.0), you must freeze the specific resin grade, shrink basis, cavitation, gating type, and critical cooling circuit paths. Changing these after the steel is cut often requires expensive welding or complete insert remakes, causing significant delays and compromised tool integrity during final production.
In the United States, the 1/4" NPT and 1/2" NPT (National Pipe Thread) standards are the defaults for mold cooling ports. Ensure your spec sheet explicitly calls for NPT threads rather than BSP (British Standard Pipe) to maintain compatibility with standard US manifolds, flow meters, and industrial water hookups common in North American molding facilities.
Identify Critical-to-Quality (CTQ) dimensions on your 2D print and link them to the spec sheet with required CPK values (typically > 1.33). Specify that these dimensions must be verified during run-off via a full FAI (First Article Inspection) using CMM or optical measurement to ensure repeatable assembly and functional performance.