Mixing
Different additives are combined with elastomers, for example, antioxidants, re-enforcing elements, pigments, processing aids, softeners, and curing agents. Dispersion kneader aids the combination since it mixes all components under high pressure, controlled heat, and stipulated mixing durations (Barbera et al. 710). The mixture generates compound lumps that are obtained from the dispersion kneader. The clumps are allowed to cool then stored for a few days to enhance the quality of the product.
Extrusion
During the extrusion stage, the rubber complex sheet is introduced into the extruder, which comprises a revolving screw within a tight-fitting hot cask. The objective of feeding the rubber into the extruder is to pressurize, mix, and soften it since it is continually channeled to a shaping die at the outlet of the extruder (Yu et al. 4). The generated product has a consistent cross-section along the span of the formed items. Characteristic produced rubber items encompass seals and gasket profiles, weather stripping, and tubing.
Calendering
In the calendaring phase, a plastic or rubber product moves across a chain of rollers in an effort of smoothing, flattening, or coalescing two or more elements. Calendered pieces may have numerous layers of polymer and elastomeric compressed together. In line with the intended application and needed appearance or texture, pieces of plastic or rubber may be polished, smoothened, refined, and made to have a raised surface or wavelike pattern (Barbera et al. 712). The final surface features rely on the pressure applied by rollers, the degree of heat, composition, surface plan, and the form of cover on the product that is calendered.
Compression Molding
Compression molding is a stage where the compound is compressed in a hot mold to assume the shape of its cavity and undergo curing attributable to the high temperature and pressure employed on the material. It is a considerable progression to generate flat sheets and fabrics with rubber coating as cured or uncured product segments (Yu et al. 4). The compound taken into the compression molding process could be in pre-shaped blanks or putty-like substances. The pressure is applied to the compound before it is forced to fill the mold cavity with a heating system that ensures effective curing.
Injection Molding
This is the phase where the compound is compressed onto a mold cavity via an opening. Rubber products in strip form are introduced into injection molding machines. The products are then pushed forth by a feeding screw and taken into a split mold, entering its cavity through a runner system. The injection molding machine resembles an extruder with the major difference between them being in the screw action (Yu et al. 4). In the extruder, the screw turns continually to create a continuously long product, for example, a rod or pipe. However, in the injection molding, the screw does not just only keep rotating but also moves back and forth consistent with the progress of the molding cycle.
Vulcanization
This process results in valuable rubber products such as mechanical items and tires. Unvulgarized rubber is taken into the vulcanization process to make it less sticky and enable it to retract to its initial shape following deformation. Rubber and sulfur, together with other elements, are heated to over 300 degrees Fahrenheit in a pressurized mold (Barbera et al. 715). Heat and chemicals introduced in the vulcanization process harden the rubber and enable it to retract easily.
Curing Machines
In curing machines, rubber extrudate is refined to sustain its shape and obtain essential physical characteristics. This is achieved by a chemical reaction (the joining of molecules) from sulfur curing components (Barbera et al. 713). Curing starts when extrudate temperature is increased by feeding it into media such as microwave or hot air system. The size of the rubber changes slightly in the curing process and this should be considered in the die design.
Works Cited
Barbera, Vincenzina, et al. “Serinol Derivatives for the Sustainable Vulcanization of Diene Elastomers.” Rubber Chemistry and Technology, vol. 91, no. 4, 2018, pp. 701-718.
Yu, Kunhao, et al. “Additive Manufacturing of Self-Healing Elastomers.” NPG Asia Materials, vol. 11, no. 1, 2019, pp. 1-11.