Glossary of Rubber Terminology
Whilst we try to be as straight-forward as possible, using language and phrases that most people will be able to understand, there is no getting away from some important terms within the industry.
Here we do our best to outline some of the more often used phrases, explaining their actual meaning and uses as far as possible. Our glossary of rubber terminology helps remove some of the questions, queries and unclear words, allowing you to more fully understand the applications, attributes and specifications of our range of rubber products; including rubber extrusion, rubber gaskets, rubber sheet, tube and matting.
Abrasion resistance is the ability of certain materials to withstand rubbing, wearing, scraping etc.
Selecting a material with a high abrasion resistance is often vital for situations in which the product is going to be under constant moving/mechanical contact. Allowing the piece to maintain it's shape, size and structural integrity, without the need for frequent replacement.
An autoclave is - for all intents and purposes - an industrial, pressurised oven.
It's used as part of the curing process, in particular for our extrusion products, to finalise the curing and hardening of the extruded profiles.
A compound - in the rubber trade - is simply a combination of different ingredients to make a raw material. They're often created with a view to adding specific properties (such as strength, flexibility and improved resistance to gases/oils etc.) to a rubber material, ahead of processing into products.
A CE (or 'Conformité Européene', which literally translates as European Conformity) marking is essentially the approval of a product that has been manufactured within the European Economic Area. In order to achieve this certification mark, the products - and manufacturing processes - must have conformed with a number of health, safety and environmental protection standards.
The term 'closed-cell' typically refers to foam products. In a closed-cell foam, for instance, the bubbles throughout the product are much smaller and tighter knit, resulting in a denser, more stable material. The result is improved insulation and a harder wearing product, than that of an open-cell alternative.
*See 'Open-Cell' for further detail of this.
CNC stands for 'Computer Numerical Control'. Our engineers use CNC to translate drawings from a computer, into directions that our cutting machines are then able to follow - like plotting points on a map - in order to produce intricate and accurate gaskets, pads, washers etc.
Curing is the process of stabilising materials, after they've been processed. For instance, in extrusion, once the material has been fed through our extruder and has been manipulated into the correct profile shape, it is still very malleable; often not suitable for it's desired used.
After curing however, the material becomes firmer and it is then able to be cut and used as appropriate i.e for boat fendering, bumpers etc.
The density is essentially how compactly structured a material is. For instance, an open-cell foam is a much less dense material, than a solid nitrile sheet.
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber and used across an array of applications, thanks to the desirable attributes and characteristics it holds.
Available in a range of different hardnesses (see 'Shore' for more information on understanding the hardness of rubber), EPDM has excellent resistance to heat, ozone, steam, weather and is an electrical insulator.
The extrudate is just the original/raw material that is forced through the extruder during production.
To extrude is the process of forcing a raw material, heated to a high-temperature, and then forced under pressure through a machined die/tool. The end result of the material being extruded, is that it has now formed a new shape/profile, suitable for the application in which is what designed.
The U.S. FDA (Food and Drug Administration) tests, and approves a wide range of items for - in our instance - medical appliances. This means that, should you require any of our products for use in medical equipment etc. selecting an FDA approved material, would be the most suitable option.
Hardness, when referred to in the context of rubber, is literally how firm or how soft the material is. Please see 'Shore' for a more detailed explanation on the measuring of rubber hardness.
Insertion rubber is an industrial strength rubber sheet, that is then combined with a cloth reinforcement material; improving strength and tear resistance qualities, creating a more hard-wearing sheet.
Natural Rubber (NR)
Natural rubber is the most organic of all rubber variants, though it is not used extensively within industrial applications, as it lacks a number of typically required properties, properties that are offered by alternative materials such as EPDM, nitrile and neoprene.
Neoprene (also polychloroprene or pc-rubber) is a family of synthetic rubbers that are produced by polymerization of chloroprene. From a material perspective however, neoprene exhibits good chemical stability and maintains flexibility over a wide temperature range, meaning this is an excellent rubber choice for fan belts, membranes and electrical insulation.
Nitrile or 'Nitrile Butadiene Rubber' is often used in automotive and aeronautical applications, due to it's excellent resistance to oils and fuels. Nitrile is also used in a number of goods, including footwear, adhesives, sealants, sponges, expanded foams, floor mats and a range of other products.
If you require rubber for oil hoses, grease guns, gaskets for oil pipelines, automotive pipes/gaskets etc. then you need to choose a rubber with excellent oil resistance. Natural rubber offers poor oil resistance and will warp, bloat and disintegrate in a short period of time, when in contact with oil. Materials such as neoprene, silicone and nitrile offer much greater oil resistance and are, therefore, more suitable in oil contact applications.
Open-cell, most typically used in relation to foam, results in the material having a less dense profile than that of closed-cell products. This lighter profile creates softer, more breathable, foams for use in cushions, mattresses and in acoustic/soundproofing environments.
PAH’s (Polycyclic Aromatic Hydrocarbons) are proven to have a carcinogenic effect and therefore deemed extremely dangerous. There are a number of EU regulations and legislations in place, to restrict and limit the use of PAH's in rubber products.
Plasticisers, often used in the form of liquids, are additives that increase the plasticity or decrease the viscosity of a material. These are the substances which are added in order to alter their physical properties of materials.
Some materials, such as silicone for example, may require what is known as a 'post cure'. This is often another period of reheating at a high-temperature. This post cure period is implemented after the initial cure has taken place and serves to further stabilise the rubber, ensuring a stronger product for customers.
The processing of materials that we take part in here, is the processing of rubber via extrusion and curing, taking a raw material and creating products for businesses and individuals to use as required.
PUs (Polyurethanes) are a family of elastomers that make up an array of artificial rubbers, with a wide array of hardnesses and applications.
Registration, Evaluation, Authorisation and Restriction of Chemicals is a European Union regulation dating from 18 December 2006. REACH addresses the production and use of chemical substances, and their potential impacts on both human health and the environment.
RoHS stands for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products. All applicable products in the EU market after July 1, 2006 must pass RoHS compliance.
Styrene-Butadiene Rubber (SBR)
Styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene. These materials have good abrasion resistance and good aging stability when protected by additives. Their applications stem to car tyres, footwear, hoses, conveyor belts and many other.
The Shore Scale, is the preferred method for measuring the hardness of rubbers/elastomers and is also commonly used for 'softer' plastics such as polyolefins, fluoropolymers, and vinyls. The Shore A scale is used for 'softer' rubbers while the Shore D scale is used for 'harder' ones. More information regarding the scale is available here.
A big problem that must be faced when manufacturing rubber products is prospective shrinkage. This basically means that when the rubber has been moulded etc. the parts come out slightly smaller than the mould. In order to combat this, the moulds must be designed with knowledge of the materials rate of shrinkage and must be adapted before manufacturing.
Silicone rubber is a rubber-like material composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers often contain fillers to improve properties and/or reduce cost.
A synthetic rubber is any artificial elastomer, the opposite of natural rubber. These are man-made materials, developed to fulfil the specifications and needs of any desired applications. Around 2/3rd of rubber produced is now synthetic in its nature.
Tensile strength is a measurement of the force required to pull something, such as sheet, hose or tube, to the point where it breaks. The tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example tearing or snapping.