Manufacturing refers to all the processes that are used to convert raw materials or scrap into useful products by adding substantial value. It must be noted that Manufacturing is not any single process; instead, it is the term that represents a number of processes that are used to convert raw material or scrap into desired product. There exists a large number of manufacturing processes in order to process a wide variety of materials in different ways to satisfy perpetually varying demand. Thus it is convenient to group them depending on their primary objective to use; and hence, three classes arise, as discussed below.
- Primary Manufacturing Processes
- Secondary Manufacturing Processes
- Advanced Manufacturing Processes
In general, primary processes convert raw material or scrap to a basic primary shaped and sized product. Secondary processes further improve the properties, surface quality, dimensional accuracy, tolerance, etc. Advanced processes usually (but not necessarily) manufacture desired products at one step. Advanced processes are beneficial to provide magnificent properties and qualities to the products.
Primary manufacturing processes
These processes are used to convert raw material or scrap to a basic primary shaped and sized product. Such processes cannot provide exactly same product that is desired (unless the required product has very ordinary & simple shape with broad allowance on dimensions). Close dimensional tolerance cannot be achieved by these processes. Achievable surface finish and surface integrity of the products are not very impressive. Appearance of the product is also poor. However, these processes are much useful to give a basic property, shape and size so that it can be further processed in the secondary manufacturing processes. Various primary manufacturing processes are:
- Forming, such as Forging, Rolling, Extrusion, etc.
- Joining, such as Welding, Soldering, etc.
Secondary manufacturing processes
These processes are used to further modify the output of primary manufacturing processes in order to improve the material properties, surface quality, surface integrity, appearance and dimensional tolerance. The input material for these processes must have some specific shape and size; otherwise products may not be accommodated within the machine facility. Various secondary manufacturing processes are:
- Surface working, such as Heat Treatment, Coating, etc.
Advanced manufacturing processes
(This classification is ambiguous, but widely accepted!) With the advancement of technology, a number of new methods and technical systems have been developed that can directly convert raw material or scrap into products having close tolerance and dimension, superb surface quality, desired properties and magnificent appearance. Thus these processes eliminate the need to pass a product through a number of primary and secondary processes; and therefore, production time and cost can be reduced. Some of these processes are unique and completely different from above two groups; however, others are the developed version of processes from above two groups. Most of these processes use efficient, costlier and precision machines inbuilt with computer control system. The concept of Additive and Subtractive Manufacturing is associated with advanced manufacturing system. Various advanced manufacturing processes are:
- Powder Metallurgy (PM)
- Rapid Prototyping (RP) or 3-D Printing
- CNC machines, machining centers, etc.
- Dye Casting, etc.