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Types of Metal Casting
2021-11-04 08:33:09

There are many metal casting methods to choose from. What type of casting is most efficient depends on the metals used, the size of the run, and the complexity of the casting.

Sand casting

Sand casting is the most common method of metal casting. The process of its manufacture is at least three thousand years old: the first evidence of clay casting comes from China during the Shang Dynasty (1600 to 1046 BC).

No wonder the process is still so popular: sand is cheap, plentiful, pliable and able to withstand heat.

Cores made from sand are easy to remove: they can be shaken out with a shaker. The runners and sprues for introducing the metal into the mould cavity are cut by hand by experienced moulders or created as part of the model.

The surface finish of sand castings is often rough and the dimensional tolerances are imprecise, making sand casting ideal for the production of large, robust parts, from decorative fences to cast iron pans to automotive engine parts.

Grey Iron Sand Casting Spare Parts

Grey Iron Sand Casting Spare Parts

Centrifugal casting

In true centrifugal casting, a water-cooled mould rotates around its central axis at high speed while liquid metal is injected. The centrifugal force pulls the liquid metal into a uniform layer along the surface of the mould. In order for this method to work, the final casting must have a uniform geometry around the axis of rotation. This form of casting is therefore best suited to moulds that are roughly cylindrical or circular in shape, such as tubes or rings.

Investment casting (lost wax casting)

Sand casting is by far the most common form of metal casting, but there is one aspect of sand casting that makes it unsuitable for certain projects. Sand casting models need to be removed from the moulds they are created in and this can mean complex model construction. Drafting requirements, parting line locations, gates, risers and cores require the mould maker to carefully consider the needs of the model at each stage of the casting process.

Lost wax, investment or precision casting processes are alternatives to sand casting for most grades of metal, even high melting point ferrous alloys, while avoiding some of the mould making challenges associated with sand casting. Investment mould casting offers excellent surface finish and high dimensional accuracy.

OEM Mould Casting Stainless Steel Auto Parts

OEM Mould Casting Stainless Steel Auto Parts

Full mould or foam casting process

The full or foam casting process is a combination of the sand and investment casting processes. A foam polystyrene pattern is used. In fact, the foam model can be finished by means of a gate and runner system and the draft allowance can be eliminated. Sometimes the model is removed before filling, but with some foam, the model can remain in the mould and evaporate as soon as the hot metal is poured in.

This process is ideal for casting one or a few pieces, but sometimes the foundry will produce foam models in large quantities for mass production. There are additional costs associated with the manufacture of equipment that can destroy the foam models, but if the models are very complex, the economics of the whole casting process are usually favourable.

Comparing casting processes

Consultation with the metal casting manufacturer will help to find the most cost effective way of casting the project. In general, ferrous metals will be cast using one-off moulds, while non-ferrous metals have a wider range of possibilities, but there are exceptions to even this simple rule.

Entering the process with a clear understanding of the project requirements will help to select the best casting process. Does the design need to be precisely dimensioned? How thin do the walls need to be? What is the size and weight of the final casting? What is the surface finish? Knowing the answers to all these questions in advance will help savvy designers understand and guide their product through the casting process, finding the best and cheapest process to complete their work.

Baoding Bangsheng came from an integrated metal fabrication manufacture. In order to provide more professional trade service for overseas customer, we establish the special company to supply trade service. At present, our trade service mainly centers around casting, forging, cnc machining and involves sheet metal processing, mechanical assembly etc.. If you want to get more information about the different types of casting, welcome to contact us today or request a quote.


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