Die Casting Technology

Definition and Technical Principles

Die casting, formally known as pressure die casting, is a casting method where molten or semi-molten metal is injected at high speed into a metal mould and solidifies under pressure. Its defining characteristics lie in "high pressure" and "high speed"—typical injection pressures range from 30 to 70 MPa, metal injection velocities reach 0.5 to 50 m/s, and cavity filling takes a mere 0.01 to 0.2 seconds. This fundamental mechanism sets die casting apart from other casting techniques, enabling superior production efficiency and exceptional dimensional accuracy. The process typically entails pouring molten metal into the shot chamber, driving the plunger to inject metal into the mould cavity at high speed, rapid cooling and solidification under pressure, followed by mould opening and component ejection.

Core Advantages and Process Characteristics

The advantages of die casting technology span multiple dimensions. Exceptional production efficiency enables straightforward mechanisation and automation, allowing the production of intricate thin-walled components—with minimum wall thicknesses of just 0.3 mm for zinc alloys and approximately 0.5 mm for aluminium alloys. High dimensional accuracy is another hallmark, with casting tolerances achieving CT3 to CT6 and surface roughness values of Ra 0.8 to 3.2 μm, eliminating the need for post-machining in most applications. Furthermore, inserts can be integrated directly into die castings, conserving precious metals while eliminating downstream assembly steps. Replacing steel structures with aluminium die castings generally delivers weight savings of over 30%, whilst modular design consolidates multiple parts into single units, significantly cutting total component counts.

Key Limitations and Process Constraints

Die casting technology also faces distinct physical constraints. Due to the ultra-high filling speed, air inside the mould cavity cannot be fully evacuated, making castings susceptible to porosity and shrinkage defects; consequently, conventional die castings generally cannot undergo heat treatment. Tooling is complex with long manufacturing lead times and high capital costs, rendering the process uneconomical for low-volume production. Substantial machinery investment, along with limitations in clamping tonnage and platen dimensions, also makes conventional die casting unsuitable for ultra-large structural components. Material selection is likewise restricted, being primarily applicable to non-ferrous alloys such as zinc, aluminium, magnesium, and copper.

Transformation in the New Energy Vehicle Era: Integrated Die Casting

Conventional die casting has primarily been utilised for small to medium-sized components such as engine blocks, gearbox casings, and alloy wheels. With the accelerating demand for vehicle lightweighting and manufacturing efficiency in the new energy vehicle era, die casting is undergoing a profound evolution into "integrated die casting". Utilising ultra-large casting machines ranging from 6,000 tonnes to over 16,000 tonnes, this technology moulds large body structural assemblies—such as the rear floor, front compartment, and battery tray, which previously required stamping and welding dozens or hundreds of individual parts—into a single integrated unit in one go.

In 2025, Dongfeng Motor commissioned the world's largest 16,000-tonne integrated die casting production line, consolidating a battery tray previously made up of over a hundred components into a single-piece unit and slashing cycle times from several hours of conventional welding to just 2 to 3 minutes. Compared to traditional fabrication and welding processes, integrated die casting reduces rear floor weight by 10% to 20% and boosts body torsional rigidity by 10% to 20%, effectively extending the driving range of new energy vehicles. The success of integrated die casting relies on the close synergy across materials (heat-treatment-free aluminium alloys), structural engineering (topology-optimised design), and manufacturing processes (high-vacuum die casting and intelligent thermal management).

Industry Application and Future Outlook

Originally pioneered by Tesla, integrated die casting technology has now expanded to numerous mainstream carmakers, including NIO, XPENG, Volvo, Toyota, and Volkswagen. Dongfeng Motor has become the industry's first vehicle manufacturer to establish a full-body integrated die casting footprint covering the front compartment, battery tray, and rear floor. The automotive sector continues to advance towards larger clamping tonnages (16,000 tonnes and above), thinner wall sections, and higher component consolidation. Ongoing research into replacing aluminium with magnesium alloys is also progressing, which is poised to further enhance vehicle lightweighting.