Manufacturing as we know basically refers to the processes and techniques of converting raw materials into finished goods fit for different uses in domestic and industrial sectors. The main processes used for the same are listed as follows:
Casting is perhaps one of the oldest techniques of manufacturing and basically it refers to the process of using molten metal and letting it solidify inside a mould or container which is of the shape of the required part. Obviously the logic behind using this technique is that it is easier to give shape to certain elements like sand, plaster etc as compared to solid metals. So when the shape is set in the softer element the metal is melted and poured inside which then solidifies in the desired shape, after which some sort of machining etc might be required to properly finish the product. Of course casting is again of different sub-types such as investment casting, permanent mould casting, sand casting and so forth although the detailed discussion of each of these is beyond the scope of this article.
Forming refers to the particular set of manufacturing processes which involve changing the shape or geometry of materials with the application of heat, pressure etc without using any sort of cutting or metal removal. In one way even casting can be said to be a subset of forming and more popularly it covers techniques such as forging, rolling, bending and so on. Each of these processes in turn have several sub-divisions for example forging can be either hot forging or cold forging.
Opposite to the definition of forming, machining refers to the manufacture of products using metal removal techniques such as turning, drilling, milling, planing, honing etc. done with the help of powerful machine tools and strong cutting tools.
As the name itself suggests, joining refers to the manufacture of materials by various joining processes including but not limited to welding, soldering, brazing, fastening and so forth. The exact technique used depends on the type of materials to be joined and the strength of the joint required. For example soldering might be a good choice for joining electronic components to a PCB (Printed Circuit Board), but welding would be feasible for structural parts of a building.
The above list cannot be said to be exhaustive in any manner and new developments in science and technology also pave way for new and more efficient techniques of manufacturing, some of which might be of very specialized use such as spacecrafts and so forth. Some of the non-conventional techniques which are also gaining in popularity currently include some of the following as well.