Sand Casting
NGR delivers top-notch sand casting parts and components to a variety of industries, including automotive, transportation, mining, petrochemical, electrical, and energy sectors. Our sand casting capabilities extend to parts weighing up to 10 metric tons, with materials ranging from aluminum alloy and ductile iron to brass alloy and gray iron. We provide precision CNC machining and other secondary operations, along with rapid prototyping services. Whether you require low or high-volume production, NGR welcomes all your sand casting needs.
What Is Sand Casting?
Sand casting, alternatively referred to as sand molded casting, is a manufacturing process that employs non-reusable sand molds to shape metal castings. It serves as a widely adopted production technique for manufacturing various metal components, ranging from a few ounces to several tons in size. The versatility of sand casting extends not only to accommodating a diverse range of product sizes but also to its ability to create intricate and highly detailed castings, with the capability to cast nearly any type of metal alloy.
What does the Sand Casting process entail?
Mold-Making: The initial phase of the sand casting process involves creating a mold, an essential requirement for each casting. To form a sand mold, sand is placed into each half of the mold. The sand is meticulously packed around a pattern, which replicates the shape of the intended casting. Upon removal of the pattern, it leaves behind a cavity that defines the casting's shape. Any internal features of the castings that cannot be created by the pattern are shaped using separate sand cores before mold formation. The time taken for mold-making encompasses tasks such as pattern placement, sand compaction, and pattern removal. The duration of mold manufacturing is influenced by factors such as component size, core count, and sand characteristics. Lubricant is typically applied to the mold cavity's surface to aid in casting removal. The selection of the lubricant depends on the sand and molten metal temperatures.
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Pouring: Following mold creation, preparations are made for pouring the molten metal. Firstly, the cavity's surface is lubricated to ease the removal of the castings. Subsequently, the core is positioned, and the mold halves are securely closed and tightly clamped together. Maintaining a sealed mold is crucial to prevent material loss. The molten metal is maintained at the required temperature in the furnace. Once the mold is sealed, molten metal is poured from the furnace's holding vessel into the mold. Pouring can be done manually or by automated machines. Sufficient molten metal must be poured to fill the entire cavity and all mold channels. The filling process occurs rapidly to prevent premature solidification of any metal portion.
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Cooling: As soon as the molten metal is poured into the mold, it begins to cool and solidify. The final shape of the casting takes form as the entire cavity fills and the metal solidifies. The mold can be opened once the cooling process is complete. Estimating the required cooling time depends on factors such as the casting's wall thickness and the metal's temperature. Most potential defects arise during the solidification process, including shrinkage, cracking, or incomplete solidification. Careful design considerations can mitigate these issues during part and mold design.
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Removal: After a predetermined period, the sand mold is broken, and the castings are extracted. This step, often referred to as "shakeout," typically involves the use of a vibrating machine or burning out any sand residue. Upon removal, the castings may retain some sand and oxide on their surfaces. In some cases, blasting is employed to eliminate residual sand, especially from inner surfaces, and enhance surface smoothness.
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Trimming: During the cooling process, material from the mold channels solidifies on the castings. This excess material must be manually trimmed through cutting, sawing, or the use of a trimming machine. The time required for trimming correlates with the casting's size, with larger castings demanding longer trimming durations. Waste generated during this trimming can be discarded or recycled within the sand casting process. However, it may be necessary to treat the waste with appropriate chemicals before reuse, especially when working with non-recycled metals.
Advantages of Sand Casting
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Sand casting can accommodate a wide range of both ferrous and non-ferrous metals.
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The size, weight, and shape of parts can vary significantly, ranging from ounces to hundreds of tons.
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Compared to other processes, the tooling costs are relatively low.
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It can be used for both small and large quantities of parts.
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The cost remains relatively low, even for high-volume production of parts.
