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Reforming: Changing the shape of the material by changing the state i.e. turning from a solid to liquid and back to solid.
Metals are commonly reformed as they are originally processed in a liquid state and therefore lend themselves to being melted down and reformed.
Reforming Metals
Reforming Metals
Metal exists in a liquid state when formed so it lends itself particularly well to being moulded again by being melted back into a liquid form.
Sand Casting
Sand Casting
Sand Casting is also known as sand moulded casting. It is a metal casting process characterized by using sand as the mould material. The term ‘sand casting’ can also refer to an object produced via the sand casting process. Sand castings are produced in specialized factories called foundries. Over 70% of all metal castings are produced via a sand casting process.
In addition to the sand, a suitable bonding agent (usually clay) is mixed or occurs with the sand. The mixture is moistened, typically with water, but sometimes with other substances such as petrol, to develop strength and plasticity of the clay, and to make the aggregate suitable for moulding. A common casting sand is known as Petrabond.
The sand is typically contained in a system of frames or mould boxes known as a 'flask'.
The mould 'cavities' and 'gate' system are created by compacting the sand around models, or patterns, or carved directly into the sand.
The sand needs to be broken up to remove the metal object, which in turn needs to be left to cool.
It is quite a slow process.
Link to local companies in Thailand who Sandcast:
www.teamco.com.tw/en/page/Casting-Foundry-in-Thailand/casting-foundry-thailand.html
Die casting
Die casting
Die Casting is a metal casting process where molten metal is forced under high pressure into a mould cavity. The mould cavity is created using two hardened tool steel 'dies' which have been machined into shape, and work similarly to an injection mould during the process. Most die castings are made from non-ferrous metals, specifically Zinc, Copper, Aluminium, Magnesium, Lead, Pewter and Tin-based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.
The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high volume production. Manufacture of parts using die casting is relatively simple, involving only four main steps, which keeps the incremental cost per item low. It is especially suited for a large quantity of small to medium sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency.
There are several different methods which can be used: Gravity Die Casting, Pressure Die Casting, Industrial Die Casting
Gravity Die Casting
Gravity Die Casting
As its name implies, this method uses gravity to force the molten material into the mould due to the weight of the metal.
Pressure Die Casting
Pressure Die Casting
This method uses a Ram to force the molten metal into the former (mould) using either a hot or cold chamber.
The additional pressure ensures better accuracy and detail.
Industrial Die Casting
Industrial Die Casting
This method refers to the use of multi-slide die castings. Traditional die casting uses just two halves of a die to form the shape, making it difficult to produce more complex shapes.
By using four or more slides, complex 3D shapes can be achieved, however these sliding moulds cost more money.
Extrusion
Extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is 'pushed' or 'drawn' through a die of the desired cross-section. The extrusion process can be done with the material hot or cold. Aluminium extrusions are very common and used for window frames and within construction.
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