JÄGER Wiki
In our JÄGER Wiki we have summarized some basic terms of rubber and plastics processing. In addition to a selection of different materials, you will also find a short description of recognised manufacturing and testing methods.
Acrylate Rubber (ACM) / Ethylene Acrylate Rubber (AEM)
Acrylonitrile Butadiene Rubber (NBR)
The demand for an oil, grease and fuel resistant rubber led to the development of acrylonitrile butadiene rubber, colloquially known as nitrile rubber (NBR), in the 1930s. Due to the proportion of acrylonitrile units along the polymer chain, NBR has good to excellent resistance to mineral oils, fuels and solvents. At the same time, reinforced NBR vulcanizates show good mechanical properties.
Products made of NBR are always interesting when good resistance to oils, greases and fuels is required. This can be in the food sector, but also in technical areas or the automotive industry. The products range from hoses, O-rings, balls and flat seals to complex molded parts.
Butadiene Rubber (BR)
Butadiene rubber is mainly used in the tire industry as a blending component. The addition to natural rubber or styrene-butadiene rubber makes it possible to significantly improve the abrasion and rolling resistance of a tread compound. In technical rubber goods BR is used to improve the elasticity of other rubbers in conveyor belts, shoe soles, roller covers or bearing elements. Pure BR compounds are generally not used due to their difficult processability.
Butyl-Rubber (IIR)
A large part of the IIR rubber production is used in tire construction. As a so-called innerliner, the particularly low gas permeability is used to produce a tubeless tire. IIR is also used for bicycle tubes. The high damping capacity allows the use as a buffer spring or damper. IIR is also used to manufacture heat-resistant products such as bellows or boiler seals and for seals in contact with polar solvents. A further field of application is the production of chewing gum masses.
Chloroprene Rubber (CR)
In the course of the developments in the field of synthetic rubbers at the beginning of the 20th century, it was possible to produce chloroprene rubber (CR), a rubber similar to the general-purpose rubbers SBR and BR, which however showed a significant improvement in its aging properties. This special property, coupled with good mechanical behavior, but also significantly better resistance to acids, alkalis and polar chemicals, made chloroprene rubber the most important special-purpose rubber for many years. CR is also resistant to oils and greases and, to a limited extent, fuels.
CR-based compounds are used in many technical rubber products. The good aging properties and increased media resistance at a physical value level comparable to that of general-purpose rubbers make CR products interesting for stressed parts in outdoor applications and in contact with many different media. This includes bellows, cable sheathing, hoses, stop buffers and conveyor belts. CR is also used in the production of sports articles and clothing in contact with seawater. Here often as a foamed version. In dissolved form CR is a main component of many adhesives.
Compression molding process (CM)
Compression molding (CM) describes a discontinuous process for the production of rubber moldings. In this process, the raw compound is placed directly or in the form of a preformed blank in a preheated cavity or a cavity of the mold. By pressing the tool halves under high pressure the mixture is brought into the desired shape and vulcanized. The vulcanized molded part is then removed hot. Compared to transfer and injection molding, the heating time is longer, as the heat transfer is only effected via the wall of the cavity. Due to the simple design, the mold costs are very low in comparison. Compression molding is particularly suitable for large-volume parts or small quantities.
Elastomers
The various elastomers or the underlying rubbers are classified into general-purpose rubbers, special-purpose rubbers and high-performance rubbers.
- All-purpose rubbers are used especially in tire construction or for increased mechanical requirements.
- Special-purpose rubbers also have special chemical or thermal resistances.
- High-performance rubbers are those that are adapted to extreme chemical or environmental influences.
Epichlorohydrin (ECO)
The properties of ECO are low gas permeability, excellent ozone and weathering resistance, good compression set and good heat resistance (up to 120°C).
Ethylene-Propylene-Diene-Rubber (EPDM)
The good resistance of EPDM to weathering of various kinds makes EPDM particularly popular for outdoor applications and as an inexpensive yet long-term resistant material in various sealing applications. Be it as a profile for sealing in the automotive sector or as an O-ring in drinking water applications for sealing taps and pipe connections. Peroxide cross-linked EPDM compounds can also be used at temperatures up to 150 °C. The resistance to greases and oils, however, is poor with EPDM.
Extrusion
Fluorosilicone-Rubber (FVMQ)
Fluororubbers (FKM/FPM)
Fluororubbers are used wherever high chemical resistance and/or high temperature resistance is required. This includes many seals and hoses in the automotive sector, but FKM is also frequently used in technical equipment.
Hydrogenated Nitrile Rubber (HNBR)
Products made of HNBR are used where an NBR reaches its limits. Here, the significantly improved high temperature range is particularly noteworthy. Similar to NBR, HNBR becomes interesting whenever good resistance to oils, greases and fuels is required. Especially in the engine compartment of modern motor vehicles HNBR is used in high temperature resistant seals and hoses.
Injection molding process (IM)
Injection molding (IM) describes a discontinuous process for the production of rubber moldings. In this process, the raw compound is first fed into a screw unit and plasticized, possibly homogenized and preheated by active heating elements and mechanically by the shear forces acting on it. A piston then presses the mixture via a distribution system into the cavities or cavities of the mold. Here, vulcanization takes place in a similar way to the TM or CM process, whereby preheating the compound significantly reduces the heating times. Injection molding is suitable for high quantities or high tolerance requirements. The tool costs are significantly higher compared to the CM process.
Kautschuk
Natural Rubber (NR)
The main area of application for natural rubber is in the field of tire construction. The low heat build-up under dynamic load and the high tear resistance due to the formation of self-reinforcing crystallites (strain crystallization), which occurs at high elongation, are the basis for use in tire tread compounds, especially for truck tires. Due to their high elasticity, other areas of application for natural rubber are in the field of (vibration) dampers and as bearings and clutches for moving parts in the automotive and mechanical engineering industries.
Due to its high tensile strength, natural rubber is used in the agricultural sector, especially for belts and tapes, but also in a variety of moulded parts and roller coatings. Natural rubber is also used in rubber-metal spring elements and buffers.
Polycarbonat (PC)
Polycarbonate (PC) is classified in the group of thermoplastics. It is especially known for its water-clear, glass-like appearance.
The material shows its strengths in insulation against electric current and has high strength, impact resistance and hardness. Due to its transparent “color” and special strength, the material is also used as an alternative to glass (e.g. burglar-resistant glazing, safety helmets and visors).
Polymer
The chemical properties such as resistance to media and ageing, but also temperature resistance are determined by the monomers, while the mechanical properties and processing behavior are determined by the chain length and the arrangement of the chains in relation to each other.
Polymerization
Rubber
Silicone Rubber (VMQ)
Silicones are also physiologically harmless and inherently flame retardant. Silicones are used in particular in seals and hoses in high-temperature and low-temperature applications, but silicones are also widely used in the medical sector or for thermal and electrical insulation of electronic components.
Styrene Butadiene Rubber (SBR)
With the development of modern synthesis processes, SBR has become the most commonly produced synthetic rubber and, in particular due to its excellent wet grip properties, it is impossible to imagine car tires without it. However, SBR also plays an important role in highly stressed technical goods, such as conveyor belts in mining, because of its special mechanical strength.
Synthetic Rubbers
Synthetic rubbers differ from one another in the structure of the polymer chains (microstructure), which leads to a large variety of types.
Transfer Molding
Transfer molding (TM) describes a discontinuous process for the production of rubber moldings. Analogous to classical compression molding, the raw compound is brought into the corresponding mold in a cavity in the mold, a so-called cavity. For this purpose, the raw mix is placed in a storage pot, which is connected to the cavity via fine channels. When the tool is moved together, a punch presses the mixture through the channels into the cavity. The mixture is preheated so that the heating time can be reduced compared to the CM process. Transfer molding is suitable for medium to high volumes. The tooling costs are significantly higher compared to the CM process.