Last updated: 2026-09-05 · 5 min read

How to Verify a Chinese Mold Factory’s Capability — What Documents, Records and On-Site Evidence Should You Request Before Paying the Deposit?

Verifying a Chinese mold factory requires specific, verifiable documents — not marketing brochures or factory tour videos. Five categories: past work evidence (CMM reports from similar programs), equipment list with calibration records, steel supply chain traceability, engineering team qualifications and quality system records. Each has red flags distinguishing a factory that can hold tolerance from one that cannot. Verification takes 2–4 weeks, costs nothing beyond review time.

Key Facts

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  • Five verification categories: (1) past work — CMM reports from 2–3 similar molds, (2) equipment — machine list, CMM brand/model, calibration within 12 months, (3) steel — mill test reports, heat treatment records, hardness values, (4) engineering — designer resume, 5+ years experience, UG/NX/Pro-E proficiency, (5) quality — in-process inspection records, corrective action logs.
  • Most important single document: CMM report from a past mold. Shows whether factory holds tolerance consistently across entire part — not just one feature. Factory that cannot produce CMM report from similar program has not demonstrated ability to measure its own work.
  • Four on-site checks: mold storage organization (labeled racks), CMM room environment (20±2°C, isolated from vibration), electrode measurement before EDM, insert photography during assembly. For first-time supplier and mold above $15,000, in-person visit strongly recommended.

    • Warpage — Part deformation after ejection caused by uneven shrinkage. Amorphous resins warp less (0.4–0.7% shrinkage). Semi-crystalline resins warp more (1.0–2.5% shrinkage). Fix: uniform wall thickness, balanced cooling, optimized gate location, adequate packing pressure. The related guide covers adjacent topics.

    What Are the Five Categories of Verification Documents?

    Category Request Check Red Flags
    Past work evidence CMM reports from 2–3 molds of similar size, complexity and material Dimensional accuracy (±0.02 mm or better), GD&T callouts, first-article vs. production consistency No CMM reports; reports with no date or mold ID; only nominal values, not actual measurements
    Equipment and calibration Machine list (brand, tonnage, year), CMM brand and model, calibration certificates CMM brand (Zeiss, Mitutoyo, Hexagon = reliable; unbranded = risk); calibration within 12 months No calibration records; CMM older than 10 years; injection machines below 80 tons for molds above 300 mm
    Steel traceability Mill test reports for cavity and core steel, heat treatment records with hardness values Steel grade matches quotation (P20, S136, H13); hardness within spec (HRC 28–32 for P20, HRC 48–52 for H13) No mill test reports; hardness outside spec; steel from unknown suppliers
    Engineering team Resumes of mold designer and project engineer, years of experience, software proficiency Designer with 5+ years; proficiency in UG/NX, Pro/E or SolidWorks; DFM and mold flow capability No named engineer; designer with less than 3 years; no mold flow simulation
    Quality records In-process inspection records, non-conformance reports, corrective action logs Inspection at each stage (rough, semi-finish, finish); documented corrective actions for out-of-tolerance No in-process inspection; no corrective action records; identical quality records across multiple molds

    A factory that refuses or delays providing any of these documents signals it cannot produce the evidence — meaning it either lacks capability or lacks discipline to maintain records. Either outcome disqualifies it from a serious mold program.

    What On-Site Evidence Should You Request During a Factory Visit?

    1. Look at the mold storage area. Well-organized storage with labeled racks (mold ID, customer, date) indicates the factory tracks tools and maintains them.
      Disorganized storage with molds stacked randomly, rust visible on parting lines or no identification labels indicates poor housekeeping — which correlates with poor machining discipline.
    2. Check the CMM room environment. CMM should be in a temperature-controlled room (20 ± 2°C), isolated from machining vibration. If CMM is on the shop floor next to a CNC machine, measurements are unreliable — thermal expansion and vibration introduce errors of 0.01–0.05 mm on parts above 100 mm.
      Ask to see the last calibration certificate and check the date.
    3. Observe the electrode manufacturing process. Graphite or copper electrodes for EDM should be measured on a CMM or tool microscope before release to EDM. If electrodes are used without measurement, the EDM cavity will not match the design — resulting mold requires hand fitting, introducing variability and extending lead time.
    4. Review the mold assembly photos. During assembly, each insert should be measured and photographed before installation.
      Photos should show insert ID, measured dimensions and date. If factory does not photograph inserts during assembly, there is no record of which insert went into which cavity — making traceability impossible if quality issue arises.

    The on-site visit reveals conditions that documents cannot capture: shop floor organization, CMM room environment, electrode measurement process and mold assembly discipline.

    Runner system — The channel network that delivers melt from the machine nozzle to each cavity. Cold runner: solidifies between shots, produces runner waste. Hot runner: stays molten, eliminates runner waste but adds $15k–$40k to mold cost. The related guide covers adjacent topics.

    Verification requires five categories of documents: past work (CMM reports), equipment and calibration, steel traceability, engineering team and quality records. The most important single document is a CMM report from a similar program. For a first-time supplier and mold above $15,000, an in-person visit is strongly recommended.

  • Key parameter identified — critical variable confirmed against spec.
  • Tolerance within achievable range — commercial ±0.15mm or tighter as needed.
  • Material matched to application — resin grade selected for end-use environment.
  • Process window validated at T1 — parameters locked after first trial.
  • Inspection method defined — CMM, visual, or functional test specified.

    • Frequently Asked Questions

    Is an in-person visit necessary, or can verification be done remotely?

    For a first-time supplier and mold program above $15,000, an in-person visit is strongly recommended. The visit reveals conditions documents cannot capture: shop floor organization, CMM room environment, electrode measurement process and mold assembly discipline.

    For a repeat order from an already-qualified supplier, remote verification (video call, document review) is sufficient. Site visit cost ($2,000–4,000 including travel) is small compared to cost of a mold that does not hold tolerance ($15,000–80,000 in mold cost plus production losses).

    What is the minimum set of documents before paying a deposit?

    Minimum set: (1) CMM report from a mold of similar size and complexity, (2) equipment list with CMM calibration date, (3) sample mill test report for cavity steel, (4) name and experience level of mold designer. If factory cannot provide these four items within one week of request, it is not ready for a serious mold program.

    Do not pay the deposit until the documents are received and reviewed.

    How do you verify that a CMM report is genuine?

    A genuine CMM report includes: CMM brand and model number, date of measurement, operator’s name, mold ID, part number, drawing revision, actual measured values (not just “OK” or “within tolerance”), and deviation from nominal. If report shows only “OK” without actual values, it is not a CMM report — it is a checklist. If report has no date or no mold ID, it cannot be traced to a specific program.

    Ask for the native data file (Excel or CSV from CMM software) — a factory with genuine measurement data can provide it instantly.

    Key Takeaways

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  • Five verification categories: past work (CMM reports), equipment, steel traceability, engineering team, quality records.
  • Most important document: CMM report from similar program — shows tolerance-holding ability.
  • On-site: organized mold storage, temperature-controlled CMM room, electrode measurement, insert photography.
  • Do not pay deposit until four minimum documents received and reviewed.

    • Verification is professional due diligence, not adversarial.
    A factory with genuine capability welcomes the request. A factory that resists, delays or provides incomplete records is signaling a problem. Cost of verification is time; cost of skipping it is a mold that does not meet requirements.

    Sources: ISO 9001:2015 — Supplier Evaluation Requirements · Society of Plastics Engineers (SPE) — Mold Making Standards · ASTM International — Mold Steel and CMM Standards · HASCO — Mold Component Quality Standards · DME — Supplier Qualification Guide

    — Arthur, Tooling Engineer at aCatMould