Process classes in the database

Additive Manufacturing

This includes a number of rapidly evolving techniques for making prototypes and models quickly therefore allowing designers to check their designs and make any necessary changes before investing in expensive tooling. A CAD model of the part is required and the model is usually built layer by layer.

Casting

Casting involves pouring molten material into a mold, where it solidifies, taking the shape of the cavity. This can be achieved under the self-weight of the metal (gravity casting) or under pressure. The mold can be made from a collapsible material, such as sand, in which case a new mold is made for each casting, or the mold can be made of a metal and therefore can be used repeatedly. Internal details in a casting are achieved using 'cores'. Castings of very complicated shapes can be produced, and most materials which can be melted can be cast. Castings can vary in mass from fractions of a gram to many tonnes.

Composite Forming

Composite forming methods vary depending on the form of the fibers used. Chopped fibers are mixed with resin and shaped by polymer molding techniques, resin-impregnated mats of fibers are laid in a mold or pressed together and then allowed to cure, and continuous fibers coated with resin are wound on a mandrel to make spherical, cylindrical and other shapes.

Deformation

Deformation is forming the solid material into shape by applying forces to it. Because the material is in the solid state, the forces required are high. For this reason, metals with very high yield stresses are deformed hot. However, many commonly used metals can be deformed at room temperature therefore eliminating the need for expensive heating equipment. The most well known deformation processes are forging, rolling and extrusion which can produce components of a variety of shapes. Forming sheets into various shapes is also a type of deformation processes. Cold forming gives a better surface finish than hot forming, and cold-formed parts generally have a higher yield strength than those which are hot-formed because the work hardening is retained.

Deposition

Deposition includes processes in which the desired shape is built up atom by atom, as in electroforming and chemical vapor deposition (CVD). A mold or a mandrel, onto which the material is deposited, creates the internal details of the component. CVD is mainly used as an additional process to deposit surface layers (to improve wear and corrosion resistance) on manufactured components.

Joining

A number of techniques allow a part to be assembled from smaller components. Welding, adhesive bonding and fastening by the use of bolts and rivets are the most widely used examples. Microfabrication refers to processes which are used to make micro components used in microelectronics and microdynamical systems.

Machining

This is the group of processes in which a shape is generated by removing unwanted material. Machining can be used to make a component from stock material but more often it is used as a secondary process to impart a shape or a level of precision to a manufactured component which cannot be achieved otherwise. Shape restrictions exist for some machining processes. For example turning can only produce axisymmetric shapes.

Molding

Molding resembles casting in that the material solidifies in a die. However, the term mainly refers to processes involving polymers or glasses. The method of introducing the polymer into the die varies depending on whether the polymer is thermoplastic or thermoset. Both polymers and glasses can also be blown into shape (blow-molding) or made into a foam. Complicated components with intricate internal details can be made in masses ranging from very tiny parts to 25 kg.

Powder Methods

As the name implies, these methods involve the use of powders which are normally pressed together and then sintered to form the desired shape. Small, intricate parts of high precision can be made. The processes are also used for forming materials which are difficult to manufacture otherwise. Also, powders of two metals can be combined together to give products with combined properties. In die pressing, the powder is placed in an open die and compressed by forcing axial plungers into it. In hot isostatic pressing (HIPing) the powder is placed in a thin-walled preform and compressed using hydrostatic pressure.