Recently, a foundry enterprise cooperating with Xinda has innovated and optimized the production process of piston castings by adopting Xinda ceramic foam filters. The scrap rate of automotive engine piston castings has been successfully reduced from 25% to 10%, greatly improving production efficiency and product quality. It fully demonstrates the outstanding performance of Xinda ceramic foam filters and provides an efficient and feasible solution for the high-quality development of the permanent mold casting industry.

Bottlenecks in Production of the Partner Foundry：

As a core component, automotive engine pistons are mostly manufactured with ZL109 aluminum alloy via permanent mold casting, subject to strict product quality inspection standards. As a dedicated eutectic alloy for pistons, ZL109 aluminum alloy features excellent high-temperature strength, low expansion coefficient and good wear resistance, making it the core material for internal combustion engine piston manufacturing. However, defects such as inclusions, porosity, shrinkage cavity and shrinkage porosity have long been key bottlenecks restricting product qualification rates in traditional casting processes.

Although the partner enterprise had optimized multiple procedures including smelting and pouring for many times, the scrap rate of piston castings remained stubbornly at around 25%, severely undermining production efficiency. The enterprise was in urgent need of an efficient and reliable filtration solution to break through the production bottleneck.

Core Advantages of Xinda Ceramic Foam Filters：

As a benchmark product in the casting filtration sector, Xinda ceramic foam filters adopt independently developed core technologies. Compared with conventional punched iron sheets and fiber filter screens, they possess irreplaceable prominent advantages and perfectly meet the demands of permanent mold casting:

• Superior Material & Performance: Made of high-quality alumina material, the filters adapt to the operating temperature of 1250℃ for aluminum alloy casting. They feature high temperature resistance, stable chemical properties, high strength and excellent thermal shock resistance. No slag shedding or cracking occurs during transportation, handling and pouring, ensuring stable and reliable filtration performance.

• Outstanding Filtration Effect: With a unique 3D interconnected curved porous network structure, the filters boast large specific surface area and uniformly controllable pore size. They realize dual filtration via mechanical interception and deep adsorption, efficiently removing all types of non-metallic inclusions in molten alloy, with filtration performance far exceeding traditional materials.

• High Compatibility: They can be flexibly installed in external pouring cups without modifying the customer’s finalized permanent molds, greatly lowering application barriers and completely overcoming the application limitations of traditional filter materials in permanent mold casting.

At present, Xinda ceramic foam filters have been widely applied in sand casting, investment precision casting and other fields, winning high recognition across the industry.

Trial Process & Optimization Measures at the Partner Plant:

In this trial, Φ60mm×15mm, 15 PPI Xinda ceramic foam filters were selected. With precise pore size, this specification matches the flow characteristics of ZL109 molten aluminum alloy. It efficiently filters impurities while reasonably controlling the flow resistance of molten metal. The existing production process parameters remain fully unchanged with no extra process adjustment required, ensuring convenient and efficient operation.

The trial was conducted in two phases, with 5 external pouring cups used in rotation throughout the whole process, and one Xinda ceramic foam filter replaced after each pouring:

1. First Trial: A total of 12 pistons were poured. 2 were scrapped due to molten alloy leakage caused by uneven joint surface and small contact area between the pouring cup and sprue. After machining the remaining 10 delivered castings, only 1 was found with porosity defects.
2. Optimized Trial: Under the technical guidance of Xinda, new external pouring cups were fabricated with increased self-weight and precision-machined bottom planes. A total of 28 pistons were poured; only 2 were scrapped due to under-pouring caused by operational errors. Among the 26 delivered castings after machining, 23 were qualified, achieving results far beyond expectations.

Trial Results & Product Value：

• Sharp Defect Reduction: No casting was scrapped due to inclusion defects. Original shrinkage and porosity defects were significantly reduced, lifting the casting qualification rate by nearly 15 percentage points.

• Highlighted Filtration Principle: Inclusions are removed through three mechanisms: mechanical sieving, filter cake formation and deep adsorption, while gas attached to inclusions is eliminated simultaneously. The throttling and flow rectification effect stabilizes molten metal flow, avoiding gas entrapment and secondary inclusions, and reducing casting defects fundamentally.

• Upgraded Mechanical Properties: For filtered alloy liquid, the elongation increases by approximately 40%. Eutectic silicon becomes finer, primary silicon quantity decreases, and structural uniformity is greatly optimized, remarkably enhancing the durability and service life of piston castings.

• Easy Implementation: No modification to existing production equipment is needed. Continuous operation can be realized by equipping 5 external pouring cups per mold for manual mold opening and closing pouring. It is easy to promote on a large scale, helping foundries improve quality and efficiency rapidly without additional investment.

The successful application of Xinda ceramic foam filters in piston casting production not only helps the customer solve the technical difficulty of filter material placement in permanent mold casting, but also achieves dual improvement in product quality and production efficiency. It further fully demonstrates Xinda’s technical strength and product advantages in the casting filtration industry.