Currently, the cast aluminium components industry boasts substantial annual output, yet significant underutilised production capacity remains. Under these circumstances, it is imperative to expedite the transformation of development models and implement sustainable development policies. This entails not only strictly curbing the indiscriminate expansion of low-level production capacity but also progressively phasing out existing obsolete capacity. The implementation of entry criteria for the cast aluminium components sector will facilitate alignment with current industrial restructuring and upgrading requirements. It will promote energy conservation and emissions reduction across the industry, advance the broader trend of eliminating outdated capacity, curb low-level duplication and uncontrolled expansion within foundry operations, safeguard the ecological environment, and guide the foundry industry towards healthy and sustainable development.

The first is planning; poor workmanship and planning lead to defects, which arise from a critical stage in the process. When this stage is not achieved, the cast products manufactured using the tooling will exhibit flaws. The second factor concerns materials and smelting. When discrepancies arise between these elements, defects become inevitable. Smelting involves alloying metals with stainless steel products, which exhibit significant thermal expansion properties and a high susceptibility to hot cracking. As internal and external defects accumulate, casting techniques may also lead to errors. Casting technique deficiencies contribute to one aspect of this issue. What about cracks and cavities? The probability of sand defects can be addressed through process control.

Casting cracks represent a significant defect, disrupting the continuity of the metal structure. They cannot be compacted during subsequent extrusion or rolling processes, hence ingots exhibiting cracks are deemed scrap during inspection. The presence of casting cracks significantly impacts the production efficiency and economic performance of aluminium processing enterprises. Consequently, systematic analysis and research into this phenomenon are essential to implement effective measures during production that reduce the occurrence of crack defects and enhance ingot yield rates.

Key Point: In simple terms, porosity falls into two categories. The first is precipitation porosity, which occurs when gases precipitate out of the molten aluminium during solidification due to changes in gas solubility – the senior engineer has covered this in detail. The second is entrapment porosity, unrelated to the molten aluminium itself. This primarily arises from air entrained within the casting during filling due to turbulence, or from moisture present in the coating or mould cavity that has not fully dried. Entrapped porosity is closely linked to the rationality of the gating system; where it arises solely from coatings or water, it is purely due to improper operation. As for its occurrence after shot blasting, this is likely closely associated with the positioning of the high-speed transition point.

Selecting the appropriate casting process is crucial, as the quality of the casting process directly impacts both the quality of the castings and the production yield. Some domestic mould manufacturers have begun employing solidification simulation to assist in casting process design. Through computer modelling of the filling and solidification processes, they identify hot spots prone to casting defects and take measures to overcome them. This approach is highly significant and effective in enhancing the reliability of casting process design and preventing unnecessary rework during mould debugging.

Aluminium castings offer low cost, excellent workability, and resource-saving remelting for recycling, ensuring enduring application and development. Sand casting is the preferred method for aluminium castings, primarily due to its lower cost, simpler production process, and shorter production cycle compared to other casting techniques. Aluminium castings are produced by preparing pure aluminium or aluminium alloy ingots according to standard composition ratios. These are then heated manually to transform them into liquid or molten aluminium alloy. This molten material is subsequently poured into cavities using specialised moulds or corresponding processes. Upon cooling, the desired shape of the aluminium component is formed. Common aluminium casting methods include: sand casting, die casting, low-pressure casting, mould casting, and lost foam casting. Aluminium castings exhibit excellent mechanical and physical properties, offering a wide range of strength, hardness, and toughness combinations. They may also incorporate one or more specialised characteristics, such as wear resistance, high/low temperature tolerance, and corrosion resistance. Die-casting manufacturers

Aluminium casting frequently encounters oxidised inclusions, the majority of which are dispersed across the surface of the castings. Some occur in areas inaccessible to simultaneous machining, appearing yellow or greyish-white due to the abundance of ports. This phenomenon becomes apparent during machining and can be traced to causes identified during acid or alkaline pickling processes:

Every component undergoes design prior to moulding, and aluminium castings are no exception. During the design process, three key elements must be mastered: the mould, the process parameters, and the casting's structure. Only thus can the quality of aluminium castings be assured while simultaneously extending the service life of the mould.