Application evaluation of vacuum low pressure casting technology in the aerospace sector

According to the SAE website published on January 10, 2018, Gaoling (HPDC) is a traditional casting process commonly used for aluminum-magnesium alloys. However, it has some limitations, particularly in terms of porosity during the casting process, which can affect the overall quality and reliability of the final product. This has led to its limited use in high-performance industries like aerospace. In contrast, Vacuum Low Pressure Casting (SVDC) addresses these issues effectively and has gained widespread recognition in the industry.

The red arrow highlights the fuel port cover of the Boeing 737MAX, a key example of SVDC application in aerospace engineering.

SVDC allows engineers to design complex, thin-walled components that are lighter and more efficient. Unlike conventional methods, which often require thicker sections to maintain structural integrity, leading to challenges in heat treatment and assembly, SVDC enables post-casting heat treatment, improving mechanical properties and part performance. This results in up to a 20% reduction in weight, 40% thinner walls, and lower energy consumption, material costs, and environmental impact.

To evaluate the benefits of SVDC, a Process-Based Cost Model (PBCM) is used. PBCM integrates three interconnected models: technical process, production operations, and capital accounting. The technical model includes factors like materials, energy, labor, and equipment, while the operational model focuses on time and resource allocation. The capital model translates all these elements into economic costs, such as energy prices, labor rates, and equipment depreciation. These models rely on physical or statistical relationships, such as equipment capabilities, process parameters, and part performance metrics, to determine cost efficiency.

The PBCM model helps compare different processes based on production scale, part size, and application, enabling detailed profit and loss analysis.

The following table shows the cost comparison between HPDC and SVDC for flaps and two accessories. The red line represents HPDC unit cost, and the green line represents SVDC. At low production volumes, SVDC is more expensive, but as output increases, the cost becomes comparable or even slightly lower. The point where both processes have the same cost is marked with blue stars.

For large parts, when the production volume reaches 7,180 units, the unit price is $118.14, and both processes cost the same. For medium parts, at 8,230 units, the price stabilizes at $45.54. The weights of large, medium, and small parts are 22 kg, 5.4 kg, and 0.4 kg respectively.

From the cost analysis chart, we can see that SVDC is 1.2% more expensive than HPDC for small parts, and 6% more for large parts.

If the annual production of medium and large parts reaches 10,000 units, using SVDC becomes highly advantageous due to its material savings. However, for small parts, where material usage is already minimal, the benefit is less noticeable. That said, the 1.2% higher cost of SVDC for small parts can be offset by combining them with larger parts or optimizing energy use.

Looking ahead, SVDC is expected to enhance product performance, consistency, and reliability while reducing carbon emissions. As a result, it is becoming the preferred technology across many industries, especially in aerospace, where precision and quality are critical.