FJ Precision’s Gravity Die Casting Delivers Stronger, More Reliable Aluminum Parts for Critical Applications

What Is Gravity Die Casting and How Does It Work

Gravity die casting, also known as permanent mold casting, is a precision metal forming technique where molten aluminum—typically A356 or A380 alloy—is poured into a reusable H13 tool steel mold using only gravitational force. This enables controlled filling and directional solidification, critical for producing high-integrity components such as cylinder heads and pump valves.

The process relies on strict control of pouring temperature, maintained between 680–720°C for A356 to optimize fluidity while minimizing gas entrapment. Unlike high-pressure methods, gravity-fed flow ensures laminar metal movement, drastically reducing turbulence and internal porosity. According to ASTM B26/B26M, this results in castings with exceptional internal soundness, making them ideal for aerospace and automotive safety systems.

Pouring Temperature: 680–720°C (A356), optimized for minimal gas pickup
Mold Material: H13 tool steel, offering thermal stability over 10,000+ cycles
Cycle Time: 90–180 seconds, balancing productivity and controlled cooling
Typical Alloys: A356 (high strength, corrosion resistance), A380 (excellent castability)

FJ Precision engineers mold geometry and cooling rates to promote directional solidification from extremities toward risers, eliminating shrinkage voids and enhancing mechanical strength. Real-time thermal imaging and post-cast CT scanning validate each step, ensuring every part meets fatigue-resistant standards. The result is a near-net-shape component with consistent performance—ideal for applications where reliability trumps raw speed.

Why Choose Permanent Mold Over High Pressure Die Casting

Permanent mold gravity casting outperforms high-pressure die casting (HPDC) in tensile strength, ductility, and heat treatability, making it the preferred method for safety-critical aluminum components like cylinder heads and valve bodies. FJ Precision leverages this advantage to deliver parts capable of withstanding extreme mechanical and thermal loads without compromise.

Tensile strength: A356 via permanent mold achieves 270–300 MPa, surpassing HPDC’s 220–240 MPa due to reduced turbulence during fill (NADCA benchmark studies, 2024).
Elongation at break: Reaches 8–12%, nearly double HPDC’s 4–6%, indicating superior fatigue resistance under cyclic stress.
Internal defect rate: Micro-porosity averages just 0.5% volume, versus 3–5% in HPDC, as confirmed by industrial CT scanning at FJ Precision’s lab.
Heat treatability: Enables full T6 capability without surface blistering—a common failure mode in HPDC due to entrapped gases.
Secondary machining: Lower porosity reduces scrap during precision boring by up to 30%, cutting rework costs significantly.

This performance edge makes permanent mold ideal for diesel engine cylinder heads operating under 200+ bar combustion pressures. As OEMs demand certified fatigue life in lightweight structural housings, FJ Precision positions gravity casting not as legacy tech but as a strategic enabler of long-term reliability—already adopted ahead of broader industry trends.

How FJ Precision Ensures Quality Assurance in Every Cast

FJ Precision enforces a multi-stage quality assurance system compliant with ISO 9001 and IATF 16949 standards, integrating non-destructive testing (NDT), Zeiss Contura G2 CMM measurements, and real-time statistical process control (SPC) to guarantee defect-free output across all production runs.

Alloy verification: Incoming ingots are analyzed via OES spectroscopy (Thermo Fisher ARL iSpark), ensuring composition adheres to AA319 or AA356 specs within ±0.05% elemental tolerance.
Mold preparation: Graphite molds preheated to 250–300°C and inspected via infrared thermography to ensure thermal uniformity and prevent distortion.
In-process sampling: Every 15th casting cycle undergoes dimensional and visual checks; SPC data logged in Minitab-based dashboards detect drifts in tolerances (±0.1 mm).
Radiographic inspection: Internal integrity verified using a Nikon XT H 225 CT scanner, detecting voids per ASTM E505 Level 2 criteria—maximum pore size of 0.8 mm at 2x magnification.
Pressure testing: All fluid-carrying housings tested at 2.5x operational pressure (up to 750 psi) for 60 seconds; zero leakage required.
Final inspection: 100% of finished parts receive CMM reporting via Zeiss Contura, validating GD&T compliance on critical datums and sealing surfaces.

This closed-loop system supports a documented yield rate of 98.6% (Q4 2024 audit), exceeding the industry average of 96.5%. By anchoring each phase in measurable, repeatable protocols, FJ Precision maintains consistency where HPDC often fails—delivering high-integrity castings ready for AA356-T6 and A357 applications under extreme service conditions.

Which Alloys Are Best for Structural Housing Applications

For structural housing applications, aluminum-silicon alloys A356 and A357 dominate due to their excellent strength-to-weight ratio, castability in permanent molds, and compatibility with T6 heat treatment. FJ Precision selects modified A356-T6 for most high-demand housings requiring pressure integrity and thermal cycling resilience.

A356-T6: Contains 6.5–7.5% Si, 0.25–0.45% Mg, and trace Ti (≤0.2%). After T6 treatment, achieves ~310 MPa UTS, 250 MPa yield strength, and 3–5% elongation. ASM International notes its refined eutectic structure enhances crack resistance—critical for pump housings under 300 psi.
A357-T6: Features higher Mg (0.4–0.6%) and added Ti (0.08–0.2%), delivering ~350 MPa UTS and improved elevated-temperature performance. Used in aerospace-grade components where fracture toughness is paramount, though more prone to hot tearing.
C354 (Al-Si-Cu-Mg): Offers high hardness and wear resistance but limited ductility (<2% elongation); rarely used by FJ Precision due to brittleness and sensitivity to solidification stresses.

FJ Precision further enhances A356 with strontium addition (150–200 ppm) to suppress coarse platelet silicon formation, transforming it into a fine fibrous network. Verified through optical microstructure analysis, this modification improves tensile ductility by up to 40%, ensuring reliability in thin-walled castings subjected to dynamic loads. These metallurgical controls set the foundation for next-gen designs in EV transmission cases and industrial hydraulic systems.

Where Is Gravity Die Casting Used in Automotive and Industrial Systems

Gravity die casting plays a vital role in automotive powertrains, industrial fluid systems, and aerospace structures requiring porosity-free, heat-treatable aluminum components. Key applications include cylinder heads, intake manifolds, pump bodies, valve housings, transmission cases, and airframe brackets, all demanding adherence to SAE J452 or API/ASME standards.

Cylinder Heads (Automotive): Used in turbocharged V6 engines; must meet Ford specification WSS-M4G322-A (>270 MPa tensile strength); annual volumes exceed 250,000 units per program.
Intake Manifolds (Heavy-Duty Diesel): Require ASME B16.34 compliance; produced in batches of 50,000–80,000 annually for Class 8 trucks.
Pump Bodies (Oil & Gas): Designed to API 610 standards with zero leak tolerance; typical lot sizes: 5,000–12,000 units/year.
Valve Housings (Industrial Automation): Must pass NDT per ASTM E505 Level 2; average run: 20,000 units/year.
Transmission Cases (EV Drivetrains): Qualified under General Motors’ GMW16266 for burst pressure and EMI shielding; volumes growing at 18% CAGR post-2023.
Structural Aerospace Brackets: Built to AMS 4190 with HIP-treated A356.0; low-volume (500–2,000 units/year) but flight-critical.

FJ Precision serves Tier-1 automakers and industrial OEMs under IATF 16949 and AS9100D certifications, verified via supplier portals like Ford Q1 and Siemens QualiConnect. Specializing in medium-to-high volume runs, they optimize tooling amortization with lifecycle durability—especially in powertrain and pump systems requiring consistent T6 heat treatment. As EV and hydrogen compressor markets scale beyond 2025, FJ Precision remains at the forefront of gravity casting adoption.

As a trusted partner in precision manufacturing, FJ Precision MFG empowers your innovation with end-to-end solutions—from rapid prototyping to high-volume production. With cutting-edge technology, rigorous quality assurance, and deep engineering know-how, we ensure every component meets the highest standards of precision and performance. When you choose FJ Precision MFG, you’re not just getting parts—you’re gaining a strategic ally committed to your project’s success.

Your vision deserves nothing less than excellence. Visit our website to learn more about how our services in CNC machining, die casting, metal stamping, and advanced 3D scanning can bring your designs to life. For personalized support, call us at +86 136 5147 1416 or +852 6924 4741, or reach out via email at pm@fjprecisionmfg.com—we’re ready to turn your challenges into precision solutions.