Die casting in China

China leads; alternatives compete. China supplied 24.1% of US imports of HS 7616.99 aluminum articles in 2025, down from 43.1% in 2018, with Mexico close behind at 21.6% (UN Comtrade).

Is China still the default source for die casting?

China is still the largest single source, but it no longer dominates. Die casting is the process of injecting molten non-ferrous metal, mostly aluminum, zinc or magnesium alloys, into a hardened steel die under pressure to make near-net-shape metal parts, and China's lead in the US market for those parts has narrowed to a few points over Mexico.

No HS code isolates die castings, so the evidence is a proxy. HS 7616.99 covers "other articles of aluminum," which includes aluminum castings as well as machined aluminum parts not classified elsewhere. US imports under HS 7616.99 were US$1.88 billion in 2025, according to UN Comtrade, the United Nations trade database. China supplied 24.1%, Mexico 21.6%, Canada 9.0%, Vietnam 6.7%, Germany 5.4%, India 5.2% and Taiwan 4.8%. In 2018 China supplied 43.1% and Mexico 16.2%. Many die castings enter under functional headings instead (auto parts in chapter 87, motor housings in chapter 85), and those are outside this figure.

The total itself fell, from US$2.41 billion in 2024 to US$1.88 billion in 2025, the year Section 232 aluminum duties rose and the derivatives list expanded. The data show the timing, not the cause.

The verdict on this page is "China leads; alternatives compete." Tooling is the exception: China has become the largest exporter of die-casting dies, covered below. Tariffs are a second qualification. Since 6 April 2026 aluminum castings pay 50% Section 232 duty on full customs value from every origin, with separate treatment only for the UK, USMCA-qualifying goods and negotiated partners, which removes much of the metal-cost argument for buying US-bound castings in China.

How die casting works

High-pressure die casting (HPDC) is the main process. Cold-chamber machines are used for aluminum alloys such as A380 and ADC12: metal is ladled into a shot sleeve and driven into the die. Hot-chamber machines are used for zinc alloys (Zamak), where the injection mechanism sits in the melt. Low-pressure and gravity die casting fill the die more slowly and produce fewer gas pores. Large-format "giga-casting" of vehicle structures is a recent extension of HPDC.

A die-cast part is rarely finished when it leaves the die. It is trimmed to remove runners and flash (the thin metal that escapes at the parting line), usually CNC-machined on sealing faces and bores, then finished by powder coat or e-coat. Anodizing is limited on high-silicon die-cast alloys.

Porosity, meaning gas or shrinkage voids inside the casting, is the defining quality risk. It is controlled by die design, vacuum assist and process control, and checked by X-ray or CT scanning. A pressure-tight housing with hidden porosity can pass a visual check and fail in service.

The program sequence runs: DFM and casting simulation (fill and solidification), die design approval, die steel procurement and heat treatment, die machining and EDM, T1 trial shots, porosity and dimensional review, die corrections, PPAP or FAI, then production with trimming, machining and finishing. Die-steel heat treatment and trial iterations are the usual schedule drivers. No official source gives durations for these stages.

China's lead in die-casting dies

Die-casting dies are classified under HS 8480.41, molds for metal or metal carbides of the injection or compression type. Reported world exports were about US$1.27 billion in 2024. China supplied 37.4%, followed by Italy (14.0%), Japan (10.2%) and Korea (7.2%). In 2018 Italy (19.7%), China (19.1%) and Japan (18.7%) were nearly level. China's own exports of these dies rose from US$275 million in 2018 to US$529 million in 2025, with Vietnam (10.9%), Mexico (10.5%) and the US (8.6%) the top 2025 destinations.

The trade records disagree at the border. China reports US$45.7 million of HS 8480.41 exports to the US in 2025; the US reports only US$15.3 million of imports from China, out of a US total of US$90.2 million led by Japan at 28.6%. Valuation, timing, classification and transshipment commonly cause such mirror gaps. The gap is recorded here, not explained.

On cluster geography, the 2002 USITC study of tools, dies and molds placed China's industry in Zhejiang (Ningbo, Yuyao, Cixi, Huangyan, Ninghai), the Shanghai area for high-precision and automotive tooling, and Guangdong. That description is dated, and no current official source on die-casting clusters was located.

Die ownership, die life and cost structure

Die casting follows the same ownership model as plastic molds: the buyer pays for the die and takes title, and the die stays at the foundry (USITC Pub. 3556, 2002). Ownership, exclusive use and removal rights should be written into the purchase agreement.

Die life matters more than it does for plastic molds. Aluminum dies wear by heat checking, a network of fine surface cracks caused by thermal cycling, far faster than plastic molds wear. A die-life guarantee and clear repair and replacement terms prevent the most common tooling dispute: who pays for the second die.

Die cost is driven by die steel (H13-class hot-work steel and its heat treatment), cavities, slides, cooling and thermal management, part size (which sets machine tonnage) and the separate trim die. Piece price is driven by alloy cost, machine time, scrap rate, secondary machining and finishing. Quotes often carry a metal-price adjustment clause tied to an aluminum index.

Tolerances and quality documents

The industry references are the NADCA (North American Die Casting Association) Product Specification Standards for die castings, ISO 8062 for casting dimensional tolerances, and ASME Y14.5 for GD&T (Geometric Dimensioning and Tolerancing, the symbols that control form, orientation and position). As-cast tolerances are looser than machined ones, so the drawing must mark which features are machined after casting.

• FAI or, for automotive work, PPAP (Production Part Approval Process).
• CMM report from a Coordinate Measuring Machine.
• Alloy certificate with chemical composition, from a spectrometer report per heat.
• X-ray or CT porosity reports against a stated acceptance level, and leak-test records for pressure-tight parts.
• Coating thickness reports.

A tariff document now belongs on the list. Section 232 rates depend on the country where the primary aluminum was smelted and cast: Proclamation 11021 sets a 10% rate for articles of US metal and a 200% rate for Russian aluminum. A foundry that cannot trace its ingot cannot support either determination.

Tariff exposure as of October 2026

The central fact is in Proclamation 11021 (91 FR 18201), effective 6 April 2026: Section 232 duty applies to the full customs value of listed articles, regardless of metal content. Customs value is normally the transaction value, the price actually paid for the goods, so machining and finishing done in China are now dutiable at the full rate along with the metal. Annex I-A is the proclamation's list at 50%.

The path to the 50% rate ran through 2025. Section 232 aluminum was restored to 25% with exclusions ended on 12 March 2025 (Proclamations 10895 and 10896). The rate rose to 50% on 4 June 2025 under Proclamation 10947, a date taken from a law-firm summary because the Federal Register text was not re-checked for this page. BIS added 407 derivative codes on 18 August 2025, and a second round followed on 9 October 2025. Proclamation 11032 (effective 8 June 2026) added an Annex I-C at reduced rates for certain chapter 84 and 87 codes, with China at the 25% default rather than the 15% partner rate, and lowered the "entirely US metal" threshold from 95% to 85%.

• The low-metal exemption does not help aluminum castings. Annex goods with under 15% metal by weight are exempt under 9903.82.03 only outside chapters 72, 73, 74 and 76 (CBP CSMS #68253075, 3 April 2026). A chapter 76 casting is not eligible.
• The forced-labor Section 301 duty does not stack. The 12.5% duty on products of China from 24 July 2026 exempts articles under the Section 232 metals headings (FR Doc. 2026-15181). A court challenge to that action has been reported in secondary sources.
• Older China Section 301 list duties historically stacked with Section 232 on aluminum castings; whether they still do in 2026 was not re-verified, and the HTSUS chapter 99 notes generally impose other duties in addition.

Reclassifying a die-cast part under a functional heading to avoid 7616.99 does not avoid Section 232 if that functional code is itself on Annex I-A, I-B or III. A licensed customs broker should confirm the code.

Where die casting is shifting

• Mexico is near parity with China in US HS 7616.99 imports (21.6% against 24.1% in 2025). USMCA-qualifying goods receive content-based treatment under Annex I-C (Proclamation 11032), and Mexico imports Chinese dies, taking 10.5% of China's 2025 HS 8480.41 exports.
• Vietnam rose from 0.9% to 6.7% of US HS 7616.99 imports between 2018 and 2025 and was the top destination for Chinese die-casting dies in 2025.
• India rose from 2.3% to 5.2% over the same period.

Moving a casting out of China does not avoid Section 232, which applies to every origin, with separate treatment for the UK, USMCA-qualifying goods and negotiated partners. It avoids China-specific duties such as the Section 301 lists. Vietnam faces the same 12.5% forced-labor rate as China, though metal articles are exempt from that action.

Common mistakes in die casting from China

• Declaring Section 232 on metal content after 6 April 2026, when full customs value applies.
• Lacking smelt-and-cast documentation for the aluminum, which supports the 10% US-metal rate and excludes Russian aluminum at 200%.
• Treating zinc die castings as automatically outside Section 232 without checking the functional HTS code.
• Specifying as-cast tolerances that can only be met by machining, or not marking machined features.
• Leaving the porosity acceptance standard (X-ray level, leak rate) out of the purchase order.
• Omitting a die-life and die-replacement clause; dies wear out, and the replacement cost becomes a dispute.

Evaluating a foundry follows from these points. Ask for its casting simulation, its X-ray or CT capability or subcontractor, a sample alloy certificate, whether trimming, machining and coating are in-house, and the die life its quote assumes.

Frequently asked questions

Sources

• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, reporter USA, flow imports, HS 761699, 2018 and 2025 (2025, HTML-official)
• United Nations Statistics Division (UN Comtrade) — UN Comtrade database, all reporters, partner World, flow exports, HS 848041, 2018 and 2024 (2024, HTML-official)
• Executive Office of the President / Federal Register — Proclamation 11021, Strengthening Actions Taken To Adjust Imports of Aluminum, Steel, and Cop… (2026, PDF)
• Office of the United States Trade Representative — USTR, Notice of Actions in Section 301 Investigations ... Failure ... to Impose and Effectively E… (2026, PDF)
• comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=156&period=2025&cmd…
• comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=842&period=2025&cmd…
• federalregister.gov/documents/2026/06/04/2026-11314/further-adjusting-the-ta…
• content.govdelivery.com/bulletins/gd/USDHSCBP-4117593