In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.
Injection moulding is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals, glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and injected into a mould cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection moulding of some lower-temperature thermoplastics, can be used for some simple injection moulds.
Fibre-reinforced plastic is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass, carbon, aramid, or basalt. Rarely, other fibres such as paper, wood, boron, or asbestos have been used. The polymer is usually an epoxy, vinyl ester, or polyester thermosetting plastic, though phenol formaldehyde resins are still in use.
Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand — known as casting sand — as the mold 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. In 2003, over 60% of all metal castings were produced via sand casting.
Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The sheet, or "film" when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature that permits it to be stretched into or onto a mold and cooled to a finished shape. Its simplified version is vacuum forming.
Vacuum forming is a simplified version of thermoforming, where a sheet of plastic is heated to a forming temperature, stretched onto a single-surface mould, and forced against the mould by a vacuum. This process can be used to form plastic into permanent objects such as turnpike signs and protective covers. Normally draft angles are present in the design of the mould to ease removal of the formed plastic part from the mould.
Compression molding is a method of molding in which the molding material, generally preheated, is first placed in an open, heated mold cavity. The mold is closed with a top force or plug member, pressure is applied to force the material into contact with all mold areas, while heat and pressure are maintained until the molding material has cured; this process is known as compression molding method and in case of rubber it is also known as 'Vulcanisation'. The process employs thermosetting resins in a partially cured stage, either in the form of granules, putty-like masses, or preforms.
Blow molding is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes.
Rotational molding involves a heated mold which is filled with a charge or shot weight of the material. It is then slowly rotated, causing the softened material to disperse and stick to the walls of the mold forming a hollow part. In order to form an even thickness throughout the part, the mold rotates at all times during the heating phase, and then continues to rotate during the cooling phase to avoid sagging or deformation. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.
Lifecasting is the process of creating a three-dimensional copy of a living human body, through the use of molding and casting techniques. In rare cases lifecasting is also practiced on living animals. The most common lifecasts are 3D hand casting, casting of torsoes, pregnant bellies, faces, and genitalia and it is possible for an experienced lifecasting practitioner to copy any part of the body. Lifecasting is usually limited to a section of the body at a time, but full-body lifecasts are achievable too. Compared with other three-dimensional representations of humans, the standout feature of lifecasts is their high level of realism and detail. Lifecasts can replicate details as small as fingerprints and pores.
In-mould labelling is the use of paper or plastic labels during the manufacturing of containers by blow molding, injection molding, or thermoforming processes. The label serves as the integral part of the final product, which is then delivered as pre-decorated item. Combining the decoration process with the moulding process cuts the total cost, but can increase the manufacturing time. The technology was first developed by Owens-Illinois in cooperation with Procter & Gamble to supply pre-labelled bottles that could be filled on the product filling line. This was first applied to Head & Shoulders shampoo bottles.
Fusible core injection molding, also known as lost core injection molding, is a specialized plastic injection molding process used to mold internal cavities or undercuts that are not possible to mold with demoldable cores. Strictly speaking the term "fusible core injection molding" refers to the use of a fusible alloy as the core material; when the core material is made from a soluble plastic the process is known as soluble core injection molding. This process is often used for automotive parts, such as intake manifolds and brake housings, however it is also used for aerospace parts, plumbing parts, bicycle wheels, and footwear.
Precision glass moulding is a replicative process that allows the production of high precision optical components from glass without grinding and polishing. The process is also known as ultra-precision glass pressing. It is used to manufacture precision glass lenses for consumer products such as digital cameras, and high-end products like medical systems. The main advantage over mechanical lens production is that complex lens geometries such as aspheres can be produced cost-efficiently.
Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various time setting materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster and clay. Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods. Heavy equipment like machine tool beds, ships' propellers, etc. can be cast easily in the required size, rather than fabricating by joining several small pieces. Casting is a 7,000-year-old process. The oldest surviving casting is a copper frog from 3200 BC.
Resin casting is a method of plastic casting where a mold is filled with a liquid synthetic resin, which then hardens. It is primarily used for small-scale production like industrial prototypes and dentistry. It can be done by amateur hobbyists with little initial investment, and is used in the production of collectible toys, models and figures, as well as small-scale jewellery production.
Plastic forming machines, or plastic molding machines, were developed on the basis of rubber machinery and metal die-casting machines. After the inception of the polymer injection molding process in the 1870s, plastic-forming machines were rapidly developed up until the 1930s. With the gradual commercialization of plastic molding equipment, injection molding and extrusion molding became the most common industrialized processes. Blow molding is the third-largest plastic molding method after the injection molding and extrusion blow molding methods.
Glass-filled polymer, is a mouldable composite material. It comprises short glass fibers in a matrix of a polymer material. It is used to manufacture a wide range of structural components by injection or compression moulding. It is an ideal glass alternative that offers flexibility in the part, chemical resistance, shatter resistance and overall better durability.
Multi-material injection molding (MMM) is the process of molding two or more different materials into one plastic part at one time. As is the case in traditional injection molding, multi material injection molding uses materials that are at or near their melting point so that the semi-liquidous (viscous) material can fill voids and cavities within a pre-machined mold, thus taking on the desired shape of designed tooling. In general, advantages of MMM over other production techniques include, but are not limited to, creating parts that have an elastic modulus that varies with location on the part, creating a single-structure part with different regional materials, and also creating a single part with multiple independent polymer colors. Applications range from simple household items like a toothbrush to more heavy duty construction of items like power tools.
Transfer molding is a manufacturing process in which casting material is forced into a mold. Transfer molding is different from compression molding in that the mold is enclosed rather than open to the fill plunger resulting in higher dimensional tolerances and less environmental impact. Compared to injection molding, transfer molding uses higher pressures to uniformly fill the mold cavity. This allows thicker reinforcing fiber matrices to be more completely saturated by resin. Furthermore, unlike injection molding the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding process.
