Injection molding in China

China is the default source. China supplied 40.1% of reported world injection-mold exports in 2024 and 33.7% of US imports of HS 3926.90 plastic articles in 2025 (UN Comtrade), down from 41.9% in 2018.

Is China still the default source for injection molding?

Yes for tooling, and still yes but less clearly for molded parts. Injection molding (Google's canonical name is injection moulding, the British spelling) is the process of forcing molten plastic into a closed mold, cooling it and ejecting a finished part, and China is the world's dominant exporter of the molds that make it possible.

China supplied 40.1% of the US$12.5 billion of reported world exports of HS 8480.71 injection and compression molds for rubber or plastics in 2024, up from 26.9% in 2018, according to UN Comtrade. That share was computed over 104 reporting countries, so non-reporters are excluded. China's own mold exports reached US$6.04 billion in 2025, up from US$3.49 billion in 2018.

For parts, the evidence is a proxy. US imports of HS 3926.90 (other articles of plastics, a rough stand-in for custom molded parts) were US$11.23 billion in 2025. China supplied 33.7%, Mexico 19.0%, Canada 7.3%, Germany 5.0% and Vietnam 4.3%. In 2018 China's share was 41.9%. Many molded parts are classified by function in chapters 84, 85 and 87, so the proxy undercounts them.

The verdict on this page is "China is the default source." It holds firmly for tooling and is trending toward "alternatives compete" for parts. One finding cuts against the usual assumption: the US imports most of its finished molds from Canada (43.4% of US HS 8480.71 imports in 2025), not China (16.4%, down from 21.5% in 2018). That figure counts only molds physically imported into the US; molds built in China and kept at Chinese molders never appear in it.

How injection molding works and how a China program runs

A thermoplastic (a plastic that softens when heated and hardens when cooled, such as ABS, polypropylene, polycarbonate or nylon) is melted and injected into a mold, also called a tool. The tool holds one or more cavities (the part-shaped hollows), a core side, runners and gates (the channels that feed plastic in), slides and lifters (moving inserts that release undercuts) and ejector pins. A hot runner keeps plastic molten inside the tool and reduces scrap. Cycle time (seconds per shot) and cavitation (parts per shot) drive the piece price; mold design drives quality.

A program with a Chinese toolmaker usually runs in this order:

• RFQ with 3D CAD (STEP or IGES) and a 2D drawing with tolerances.
• DFM report (design for manufacturability), the toolmaker's review of draft angles, wall thickness, gate location and sink risk.
• Mold design approval, then steel cutting by CNC and EDM (electrical discharge machining, which burns fine features into hardened steel).
• T0 and T1 trials, the first shots; T1 is the first sample batch sent to the buyer.
• Tuning (corrections), sample approval, then production.

Mold build time depends on cavities, slides, steel hardness and the toolmaker's queue; each trial round adds a sample shipment and a review. The Chinese New Year shutdown and toolmaker backlog are the usual schedule risks. No official source gives week counts, so none are stated here.

Where molds are made in China

The most-cited official description of China's mold geography is two decades old. A 2002 USITC study found Zhejiang Province produced about 60% of China's industrial molds, concentrated in Ningbo, Yuyao, Cixi, Huangyan, Tiantai, Wenzhou and Ninghai. Guangdong tooling served toys, plastic appliances and electronics, and Dongguan showed excess capacity and strong price competition in medium-precision molds (USITC Pub. 3556, p. 4-48).

The study rests on 2002 interviews and is historical context, not a current share. No current official provincial breakdown was located.

Who owns the mold, and how tooling is quoted

The buyer usually pays for the mold and takes title, while the tool stays at the molder. USITC described this as the norm in 2002: the customer "usually takes the ownership title" of a tool that "remains at the parts producer." In China, title on paper is not the same as control. A buyer's position rests on a written tooling agreement that states ownership, bars use of the tool for other customers, grants a right to remove it, and requires a nameplate on the mold marking the owner. How Chinese courts enforce such clauses was not established by the research for this page; a trade attorney should confirm it.

Mold cost is driven by a known set of variables:

• Mold steel grade: pre-hardened P20 against hardened H13 or S136, which lasts longer.
• Number of cavities, and hot or cold runner.
• Slides and lifters needed to release undercuts.
• Part size, which sets the mold base and the press tonnage.
• Surface finish or texture.
• Guaranteed shot life, the number of cycles the tool is warranted for, and the number of included trial rounds.

Quotes usually carry a one-time tooling price plus a piece price, with tooling payment staged between order and sample approval. Some suppliers instead amortize tooling into the piece price, which usually weakens the buyer's claim to own the mold. A mold the buyer paid for separately may also need to be declared to US Customs as an assist, a buyer-supplied item added to the customs value of the parts; whether CBP treats every buyer-paid mold kept in China that way was not confirmed here, and a licensed customs broker should advise on the entry.

Tolerances and quality documents

Molded-part tolerances depend on resin shrinkage, wall thickness and mold quality. The international reference is ISO 20457 (plastics molded parts: tolerances and acceptance conditions). The mold steel itself is machined to tighter limits than the part it makes.

• FAI (First Article Inspection), a full dimensional report on the first parts; aerospace work uses SAE AS9102 forms.
• PPAP (Production Part Approval Process), the AIAG automotive package: dimensional results, material certificates, process flow, PFMEA, control plan and a Part Submission Warrant.
• CMM report, measurements from a Coordinate Measuring Machine probe against the CAD model.
• Resin certificate, the resin maker's lot certificate of analysis naming brand and grade. Substituted or regrind resin is a frequent production problem.
• Mold flow analysis, a simulation of filling, warp and weld lines, run before steel is cut.

Tariffs on molds and molded parts as of October 2026

A mold and the parts it makes are taxed under different regimes, and the gap between them widened in 2025 and 2026. An import, for customs purposes, is goods brought into the US customs territory; a mold that never leaves China is not imported, but a mold shipped to the US to move production is.

Molds entered Section 232 scope on 18 August 2025, when BIS added 407 HTSUS codes to the steel derivatives list, including the three mold codes above (FR Doc. 2025-15819). Those rates were superseded on 6 April 2026 by Proclamation 11021, which placed the mold codes on Annex III, the "Temporary Reduction List." For a country with normal trade relations, which includes China, the Section 232 duty on an Annex III item is set so that it and the Column 1 rate together total 15%.

Molded parts face a different stack. The forced-labor Section 301 action (FR Doc. 2026-15181) added 12.5% on products of China from 24 July 2026, with an exemption only for articles under the Section 232 metals headings. The same action set 12.5% on Vietnam and 10% on Mexico and India, which narrows the duty gap between China and Vietnam. A court challenge to the action has been reported in secondary sources; its status should be checked before entry. Whether a given molded-part code also carries an older China Section 301 list duty, and the current Column 1 rate for 8480.71.8045, were not verified for this page.

Two duties have dropped out: the Supreme Court's 20 February 2026 IEEPA ruling (Learning Resources, Inc. v. Trump, No. 24-1287) removed the IEEPA "fentanyl" and "reciprocal" duties, and the 10% Section 122 surcharge that followed has expired (CRS dates its end to 24 July 2026; the HTSUS compiler's note says its headings expired at the close of 23 July 2026). Injection-molding machines (HS 8477) could be touched by the Section 232 robotics and industrial machinery proclamation of 28 October 2026, which imposes no tariffs yet and names no products.

Where molding is shifting: China tooling, offshore molding

The trade flows point to a split between where molds are built and where parts are molded.

• Vietnam: China's mold exports to Vietnam rose from US$119 million in 2018 to US$632 million in 2025, making Vietnam the top destination, while Vietnam's share of US plastic-article imports rose from 1.2% to 4.3%. That pattern is consistent with Chinese-built molds being shipped to Vietnam for molding. It is an inference from trade flows, not a measured share of tooling transfers.
• Mexico: its share of US HS 3926.90 imports rose from 14.9% to 19.0% between 2018 and 2025, and it imported US$336 million of Chinese molds in 2025.
• India: small in US molded-part imports (0.9%) but a top-six destination for Chinese molds, at US$360 million in 2025.
• Canada: the largest exporter of finished molds to the US.

A part molded in Vietnam in a Chinese-built tool does not avoid China duties automatically. Origin turns on substantial transformation of the part, not on where the tool came from, and CBP examines transshipment closely. No specific CBP ruling on this fact pattern was located.

Common mistakes and how to evaluate a molder

Most losses in China injection molding programs come from the tool and the paperwork rather than the press. Importers treat the tooling invoice as proof of ownership without a tooling agreement, nameplate and removal right. They accept amortized tooling, then learn the mold is the supplier's property. They forget that moving a tool out of China is a US import under HTSUS 8480.71 and a Chinese export the supplier must cooperate with. They approve T1 samples without a CMM or FAI report against the drawing, or without a resin certificate, and later see resin substitution. And they skip mold flow analysis on cosmetic or thin-wall parts.

Evaluating a molder follows from that list. Ask for the DFM report and mold design drawings before steel is cut, a sample tooling agreement, the steel grade and shot life the quote assumes, how many trial rounds are included, and an example FAI or PPAP package. Ask who builds the mold; many molders subcontract tooling. A supplier that will not put tool ownership and removal rights in writing has told the buyer where the tool will stay.

Frequently asked questions

Sources

• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, annual HS data, all reporters, partner World, flow exports, HS 848071, 2018… (2024, HTML-official)
• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, annual HS data, reporter China (156), flow exports, HS 848071, 2018 and 2025 (2025, HTML-official)
• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, reporter USA (842), flow imports, HS 848071, 2018 and 2025 (2025, HTML-official)
• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, reporter USA, flow imports, HS 392690, 2018 and 2025 (2025, HTML-official)
• Executive Office of the President / Federal Register — Proclamation 11021, Strengthening Actions Taken To Adjust Imports of Aluminum, Steel, and Cop… (2026, PDF)
• US Department of Commerce, Bureau of Industry and Security — Adoption and Procedures of the Section 232 Steel and Aluminum Tariff Inclusions Process… (2025, PDF)
• Office of the United States Trade Representative — USTR, Notice of Actions in Section 301 Investigations ... Failure ... to Impose and Effectively E… (2026, PDF)
• US International Trade Commission — Tools, Dies, and Industrial Molds: Competitive Conditions in the United States and Selected Foreign Markets, Inv… (2002, PDF)