Polyurethane (PU)

What is polyurethane (PU)?

Polyurethane (PU) is an extremely versatile plastic that can be used as a foam, elastomer or rigid plastic. In technical applications, PU stands for highly abrasion-resistant, mechanically resilient and chemical-resistant materials that can be used in Rubber-metal composite parts can also be used as stand-alone components. Through targeted adaptation of the formulation Hardness, elasticity, density and surface properties precisely to the application.

Properties of PU

PU consists of the chemical reaction of a polyol with an isocyanate - this variety of base materials allows the production of very different types of PU: from soft foam to high-strength technical moulded parts. Relevant for industrial applications are moulded or injection moulded PU elastomers.

Typical properties:

Very high Abrasion resistance - Ideal for wearing parts
Superior tear strength and tear‑propagation resistance
Very good elasticity and Rebound properties
Resistant to Oils, greases, solvents and ozone
Cushioning, Vibration-absorbing and noise-reducing

The temperature resistance is usually between -30 °C and +90 °C, but can be extended with special formulations. PU can be easily mechanically reworked, coloured and formed into a wide variety of shapes.

Compared to classic elastomers such as NBR or EPDM PU offers significantly higher wear and tear resistance - but is less flexible in cold conditions and requires careful moulding, as postforming is hardly possible.

PU applications

Polyurethane can be found in almost all industrial sectors - in the form of:

Rollers and wheels for conveyor technology, pallet trucks, printing systems
suspension elements, Dampers, baffles or Shock absorbers
Seals and abrasion-resistant sliding components
Coatings for tools, containers or hoses
Rubber-metal composite parts, in which PU is combined with metals as an elastic functional material

PU is also used as a second, flexible component in rubber-plastic composite parts or in 2K overmoulding - especially when high durability, chemical resistance and mechanical stress are required.

Further entries

FVMQ: Fluorosilicone

FVMQ is a cold-flexible, fuel- and weather-resistant fluorosilicone elastomer that is primarily used in the aviation and automotive industries for demanding sealing applications.

Outgassing

Outgassing is the escape of volatile substances from materials and can lead to malfunctions, contamination or optical faults in sensitive applications.

Shaft seal

A shaft seal is a sealing element that seals between a rotating shaft and a housing. It prevents lubricants from escaping and at the same time protects against dirt, dust and moisture.

Azo and urea compounds

Azo and urea compounds are speciality chemicals that are used as blowing or cross-linking agents in rubber processing - especially for foams and friction-active components.

PPA: Polyphthalamide

Polyphthalamide (PPA) is a dimensionally stable, chemical and temperature-resistant high-performance plastic that is used in particular for precise, media-resistant components and rubber-plastic composite solutions.

Anti-ageing agent

Anti-ageing agents are functional additives that protect elastomers and plastics from damaging influences such as oxygen, ozone, UV radiation or heat, thereby significantly extending their service life.

Protective housing

A protective housing encapsulates sensitive components and prevents damage caused by dirt, water or impact.

Silane crosslinking

Silane crosslinking is a moisture-controlled crosslinking process for plastics and elastomers that enables mechanical stability at moderate processing temperatures.

DIN ISO 3302-1

DIN ISO 3302-1 defines the general tolerances for moulded rubber parts and is an international standard for ensuring dimensional accuracy in elastomer processing.

Seals

Seals prevent leaks in pipework, motor and system components. They also compensate for manufacturing tolerances and protect processes against pressure, temperature and media stress.

Vibration dampers

Vibration dampers reduce vibrations and noise in machines and vehicles.

Housing and cover with integrated seal

Housings and covers with integrated seals are components in which the sealing function is embedded directly in the plastic or metal part. The sealing function is usually realised as an overmoulded or pressed-in rubber sealing lip. They enable reliable sealing without a separate sealing component and are often used for compact, easy-to-install assemblies.

Rubber recycling

Rubber recycling includes mechanical, thermal and chemical processes for the reuse of vulcanised rubber products as raw materials or additives in new applications.

GRP: Glass fibre reinforced plastic

GRP (glass fibre reinforced plastic) is a robust, lightweight composite material made from glass fibres and a plastic matrix that is used in a wide range of applications in industry, construction and mobility.

Oil resistance

Oil-resistant materials permanently withstand aggressive oils and are used in seals, hoses and technical components.

Rapid tooling

Rapid tooling is the accelerated production of functional tools for the rapid production of prototypes or small series under near-series conditions.

Vacuum cups

Suction cups are suction cups made of elastomer or plastic that cling elastically to the surface and trap the resulting vacuum. Suction cups create an adhesive connection between the gripper and the workpiece by means of negative pressure.

Titanium

Titanium is an extremely corrosion-resistant, lightweight and high-strength material that is used in aviation, medical technology and for rubber-metal composite parts in aggressive environments.

Inserts

Inserts are solid components that are embedded in rubber components during processing in order to specifically extend their functionality, stability or fastening options.

PES: Polyester

Polyester (PES) is a robust, chemical-resistant thermoplastic that is used both as an engineering plastic and as a fabric reinforcement in rubber composite parts.

Stress cracking

Stress cracking is the gradual formation of cracks in plastics due to the interaction of stress and chemical media - often with critical consequences for component safety.

Engine damper

Engine dampers are elastic elements that absorb vibrations and shocks between the engine and the vehicle or machine frame. They reduce vibrations, protect adjacent components from stress and improve the noise and running behaviour of the entire system.

Express Services

Express production refers to the particularly fast production of prototypes, tools or small batches and accelerated development projects with drastically reduced delivery times.

Sealing lips

Sealing lips are flexible sealing elements that securely enclose media and remain reliably functional even in the event of rotation or pressure fluctuations.

Aluminium

Aluminium is a lightweight, corrosion-resistant material with high thermal conductivity that is used in a variety of ways as a construction material and support element in technical components.

NR: Natural rubber

Natural rubber (NR) is a highly elastic, tear-resistant elastomer made from renewable raw materials that is primarily used in dynamically stressed components such as tyres, dampers and conveyor belts.

Tool cleaning

Tool cleaning ensures reliable, clean moulding, protects against burr formation and extends the service life of tools in series production.

PC: Polycarbonate

Polycarbonate (PC) is a transparent, impact-resistant plastic that is used for high-quality housings, visible parts and functional composite components.

Vulcanisation

Vulcanisation is the process in which raw rubber is converted into a permanently elastic, dimensionally stable and durable rubber state through chemical cross-linking.

Rubber-Metal Composite Parts

Rubber-metal composite parts are mechanically stable components in which elastomer and metal are inseparably combined - ideal for bearings, dampers and technical sealing systems.

Extrusion of rubber

Rubber extrusion is a continuous manufacturing process for rubber-elastic profiles, hoses and seals in which the material is pressed through a moulding die and then vulcanised.

PU: Polyurethane elastomer

PU elastomers are dimensionally stable, abrasion-resistant plastics with high mechanical strength that are ideal for rollers, seals and shock absorbers in heavy-duty industrial applications.

Stainless steel

Stainless steel is a corrosion and temperature-resistant material that is used for durable, hygienic and mechanically resilient components in demanding technical applications.

Structural steel: S235 and S355

Structural steel (S235, S355) is a robust, easily weldable construction steel that is used as a stable carrier material in load-bearing structures, machine components and rubber-metal composite parts.

Sulphur crosslinking

Sulphur crosslinking is a proven vulcanisation process in which rubber is crosslinked with the aid of sulphur to form an elastic, dimensionally stable and mechanically resilient material.

Heat resistance

Heat-resistant materials retain their properties at high temperatures and are ideal for industrial and technical applications.

Bearing bolt

A bearing pin is a cylindrical connecting element that serves as a pivot or swivel axis for moving components. It transmits forces, guides movements and secures the position of components within a bearing or a joint connection.

Compound

A compound is a customised material mixture of polymer and additives that is specifically tailored to the requirements of a particular technical application.

Caoutchouc vs. rubber vs. elastomer

Rubber is the raw material, rubber is the end product created by vulcanisation, and elastomer is the superordinate material class of elastic polymers.

Medical device regulation (MDR)

The Medical Device Regulation (MDR) is the central EU regulation for medical devices, which places high demands on safety, documentation and market surveillance.

Adhesion

Adhesion is the physical holding force between two different materials at their interface and is a key factor for strong, durable connections in technology and industry.

ISO 14001

ISO 14001 explained: an overview of the requirements, areas of application and benefits of the international standard for environmental management systems.

Grommets

Grommets are ring- or disc-shaped protective inserts that are inserted into openings or edges to allow cables to pass through safely. Grommets protect cables and hoses from sharp edges, seal feed-throughs and can be quickly inserted into holes or gaps.

Freeze deburring

Freeze deburring is a process for removing burrs, particularly on rubber parts, by cooling and mechanical blasting.

ISO 13485

ISO 13485 explained: an overview of the requirements, areas of application and benefits of certification for medical technology.

Aramid / Kevlar

Aramid / Kevlar is an extremely tensile, lightweight and heat-resistant fibre that is used as reinforcement in rubber composite parts, sealing systems and protective applications.

Valves

Valves control, throttle or shut off liquids and gases in pipework, motors and hydraulic systems. They are crucial for process reliability and efficiency.

IIR: Butyl rubber

Butyl rubber (IIR) is a particularly gas-tight, weather- and chemical-resistant elastomer that is mainly used in tyres, seals and membranes.

CAD modelling

CAD modelling is the digital design of technical components and tools that serves as the basis for production, simulation and prototype development in industry.

Abrasion

Abrasion is the mechanically induced surface wear of a material caused by friction and has a decisive influence on the service life and usability of technical components.

Keyboard and switch covers

Keyboard and switch covers are elastic protective components that protect keys and operating elements from dust, moisture and dirt. At the same time, they maintain the operating function by transmitting the actuation feel and enabling reliable sealing.

Deburring

Deburring is the process of removing burrs from components to ensure the function, appearance and safety of technical products.

Rubber

Rubber is an elastic material of natural or synthetic origin that is vulcanised into durable components for sealing, damping and technical applications.

Elastomer rollers

Rubber rollers transmit forces, dampen vibrations and protect surfaces in printing machines, conveyor systems and packaging lines.

Cycle time

The cycle time describes the complete duration of a production run during injection moulding or pressing and is a key parameter for efficiency and output.

Elongation at break

The elongation at break indicates how much a material can stretch under tensile load before it tears.

EPDM: Ethylene propylene diene rubber

EPDM is a weather, UV and chemical-resistant elastomer with high thermal stability that is used in particular for durable seals, hoses and outdoor applications in industry and construction.

Fillers

Fillers are functional additives in rubber or plastic compounds that specifically influence mechanical properties, processability or cost structure.

Special alloys

Speciality alloys are highly developed metal mixtures for extreme requirements in technology, medicine and industry - especially where corrosion, temperature or load limits of standard materials are exceeded.

Transfer moulding

Transfer moulding is a rubber moulding process in which the material is pressed from a heated chamber into a closed mould where it is cross-linked under pressure and temperature - ideal for precise components with inserts.

FKM: Fluororubber

FKM is a heat- and chemical-resistant high-performance elastomer for seals and components in extremely demanding industrial applications.

ABS: Acrylonitrile butadiene styrene

Acrylonitrile butadiene styrene (ABS) is a robust, impact-resistant and easy-to-process plastic that is used for housings, interior parts and rubber-plastic composite components with high surface and dimensional stability requirements.

Vibratory finishing (barrel finishing)

Mass finishing or barrel finishing is a mechanical mass finishing process in which surfaces are machined and burrs removed using abrasive media and movement.

Crosslinking chemicals

Cross-linking chemicals ensure the permanent elasticity and dimensional stability of rubber through chemical reaction - a key component in the production of functional rubber parts.

HTV silicone: High-temperature curing solid silicone

HTV silicone is a high-temperature curing solid silicone rubber that becomes a permanently elastic material when heated. It combines high mechanical strength with excellent resistance to temperature, ageing and chemicals.

Suction pad

Suction cups are cup-shaped suction cups made of elastomer or plastic that cling elastically to the surface and trap the resulting vacuum. Suction cups create an adhesive connection between the gripper and the workpiece by means of negative pressure.

PA: Polyamide

Polyamide (PA) is a robust, wear-resistant plastic with very good strength and chemical resistance, which is used in particular in technical components and rubber-plastic composite systems.

Burr formation

Burr formation occurs in primary forming processes due to material escaping from mould parting surfaces and joints during forming and requires targeted reworking to ensure component quality.

Peroxide crosslinking

Peroxides are reactive cross-linking chemicals that produce stable, temperature- and chemical-resistant elastomer structures without sulphur bridges in rubber processing.

Rubber blank

A rubber blank is a non-crosslinked, mouldable elastomer precursor that is processed in moulding tools to produce elastic rubber parts.

Injection moulding

Injection moulding is a precise moulding process for manufacturing complex plastic and rubber parts in which the material is injected into a mould under pressure and cured there.

Compression moulding

Compression moulding is a process for manufacturing moulded rubber parts in which a rubber compound is compressed under pressure and heat in a closed mould and vulcanised directly.

LSR: Liquid silicone

LSR is a liquid silicone rubber produced on a VMQ or FVMQ basis and processed by injection moulding. The material combines high elasticity, purity and temperature resistance.

Plasticiser

Plasticisers are additives that make rubber and plastics more elastic and easier to process and are mainly used in flexible sealing and moulded parts.

LABS (paint wetting impairment substances)

LABS are substances that interfere with the wetting of paints and must therefore be strictly avoided or tested in paint-critical applications.

Degreasing

Degreasing is an essential cleaning step for removing residues from components to ensure optimum adhesion during vulcanisation, bonding or coating.

PPS: Polyphenylene sulphide

Polyphenylene sulphide (PPS) is a high-temperature and chemical-resistant precision plastic that is used in media-exposed and dimensionally critical components, especially in hybrid solutions.

RoHS

RoHS restricts the use of certain hazardous substances in electrical and electronic equipment in order to reduce environmental and health risks. Products may only be sold in the EU if all components comply with the specified limits for listed hazardous substances.

TPE: Thermoplastic elastomers

TPEs are elastic, malleable materials with rubber-like behaviour that can be thermally processed and recycled like plastics - ideal for flexible seals, handles and hybrid parts.

Rubber-Plastic Composite Parts

Rubber-plastic composite parts are hybrid components in which elastic and thermoplastic components are functionally combined - ideal for seals, housings and flexible technical solutions.

Pressure resistance

Pressure resistance is the resistance of a material to compressive stress and is a decisive factor for the function and service life of technical components under mechanical stress.

Series production

Series production refers to the repeated, economical manufacture of similar components in large quantities.

Glass transition temperature

The glass transition temperature (Tg) is the temperature range in which a polymer changes from elastic to glassy and largely determines its low-temperature flexibility.

Ageing

Ageing describes the gradual change in material properties due to external influences such as heat, UV radiation or media, which can lead to long-term impairment of function and service life.

Synthetic rubber

Synthetic rubber is an industrially manufactured elastomer material that is categorised into main chemical groups and whose properties can be specifically adapted to technical requirements.

Mould cavity / cavity

Mould cavities are the cavities in a mould that give the component its final geometry during the moulding process.

Elasticity

Elasticity is the ability of a material to deform under load and then return completely to its original shape - essential for flexible technical components.

HNBR: Hydrogenated NBR

HNBR is a particularly heat-, oil- and ageing-resistant elastomer that is ideal for durable seals and technical components in dynamically stressed applications.

Cold resistance

Cold resistance describes the ability of a material to remain functional and elastic at low temperatures - crucial for seals and elastomer components in outdoor or cold applications.

Bellows

A bellows is an elastic component with a corrugated, accordion-like geometry that absorbs movements, changes in length or swivelling movements without losing its protective or sealing function. It protects sensitive components such as joints, shafts or guides from dirt and moisture and at the same time enables a flexible, permanently movable connection.

Copolymerisation

Copolymerisation is the simultaneous polymerisation of different monomers to produce polymers with specifically adjustable properties for technical and industrial applications.

Rubber buffers

Rubber buffers are elastic elements that absorb and dampen shocks, oscillations and vibrations. They protect machines, devices and assemblies from mechanical loads, compensate for movements and reduce noise in technical applications.

Autoclaves

An autoclave is a heatable pressure vessel for the thermal treatment of materials - e.g. for the post-vulcanisation of elastomers or for sterilisation in medicine and technology.

Tensile strength

The tensile strength is the maximum stress that a material can withstand under tensile load and is a key parameter for the mechanical strength of elastomers.

ISO 9001

ISO 9001 is the world's most important standard for quality management. It defines how companies manage their processes so that products and services deliver consistently high quality and fulfil customer requirements.

Metal oxide crosslinking

Metal oxide crosslinking is a crosslinking process that is mainly used for chloroprene rubber and produces particularly durable, ageing and flame-resistant rubber parts.

Shore hardness

The Shore hardness measures how deeply a test pin penetrates a material and thus provides information about its degree of hardness - a decisive factor in the selection of elastic and technical materials.

VMQ: Silicone rubber

Silicone rubber (VMQ) is a heat-, cold- and UV-resistant elastomer with very good insulation and media resistance, which is frequently used in medical, food and automotive technology.

Biocompatibility

The proof of biocompatibility proves through standardised tests that a medical device or material does not cause any harmful reactions in the human body.

SBR: styrene-butadiene rubber

SBR is a cost-effective, abrasion-resistant elastomer with good mechanical properties that is mainly used in tyres, seals and general moulded rubber parts.

Polyurethane (PU)

Polyurethane (PU) is a robust, abrasion-resistant plastic with high elasticity and chemical resistance, which is primarily used in heavily loaded technical components, dampers and composite solutions.

Tempering

Annealing is a thermal post-treatment that reduces residual stresses, stabilises material properties and improves the functionality of technical components.

Primer

Primers are adhesion-promoting primers that improve the adhesion between rubber, plastic or metal and ensure a permanent bond in composite and coating applications.

PP: Polypropylene

Polypropylene (PP) is a lightweight, chemical-resistant thermoplastic with a wide range of applications that is ideal for technical plastic parts and rubber-plastic composite solutions.

Adhesion promoter

Adhesion promoters are chemical bonding agents that permanently bond rubber with other materials and thus form the basis for resilient rubber composite parts.

Rebound resilience

Rebound resilience describes the ability of a material to return energy after rapid deformation - crucial for dynamic applications such as spring elements or dampers.

Polymerisation

Polymerisation is the chemical reaction in which many monomers are combined to form long polymer chains - the basis for plastics and rubber elastomers.

Rubber expansion joints

Rubber expansion joints are flexible connecting elements that compensate for movements, vibrations and pressure surges in pipework. Thanks to their elastic structure, they can absorb changes in length, lateral displacements and angular movements and thus protect connected system components from mechanical stress, vibrations and tension in the pipework system.

Residual materials

Residual materials are recyclable material residues from production that can be specifically collected and fed back into the production cycle to conserve resources.

Assembly Services

Component assembly comprises the assembly of individual components into a functional unit as an assembly.

Calendering

Calendering is a rolling process in which rubber or plastic compounds are rolled between heated rollers. In addition to the manufacture of finished products such as rubber mats, it is primarily used in the production of rubber blanks.

FDA conformity

FDA compliance means that a material or product meets the requirements of the U.S. Food and Drug Administration and is safe for contact with food, drinking water or pharmaceutical applications. Only approved ingredients may be used and the material must not release any substances of concern into the medium.

RTV silicone: Room temperature curing solid silicone

RTV silicone is a room temperature curing silicone rubber that cures without heat or pressure. It is particularly suitable for sealing, bonding, potting and mould making and is less strong and temperature-resistant than HTV and LSR.

Tool costs

Tool costs are the expenses for the manufacture of tools and have a significant influence on the profitability of series production.

Rubber caps

Rubber caps reliably protect components from dust, moisture and mechanical impact.

Molded Rubber Parts

Moulded rubber parts are elastic components made from vulcanised rubber by pressing, transfer moulding or injection moulding. They are manufactured according to drawings and are used as sealing, damping or functional elements in technical applications.

CFRP: Carbon fibre reinforced plastic

CFRP (carbon fibre reinforced plastic) is an ultra-light, extremely strong composite material made of carbon fibres and a plastic matrix that is used in highly stressed lightweight construction applications.

brass

Brass is an easily machinable, corrosion-resistant copper-zinc alloy that is widely used as a functional and decorative metal - including in rubber-metal composite parts, fittings and electrical components.

EN 9100

EN 9100 explained: an overview of the requirements, areas of application and benefits of certification for the aviation, aerospace and defence industries.

Rubber-fabric composite parts

Rubber-fabric composite parts are elastic components with integrated fabric inserts that ensure high tensile strength, dimensional stability and dynamic load-bearing capacity - for example in membranes, seals or conveyor belts.

REACH

REACH is an EU regulation for the registration, evaluation and regulation of chemical substances in order to better protect people and the environment. Companies must prove the safety of the raw materials they use and inform customers if their products contain substances of concern.

Toolmaking

In elastomer production, toolmaking refers to the development and manufacture of high-precision tools that are used in the production of rubber, plastic and composite parts for moulding.

Profile seal

A profile seal is a seal with a defined cross-sectional shape (round, rectangular, hollow or with a complex profile) that ensures a seal between two components. It is made from elastomers and is used wherever gaps, movements or unevenness need to be compensated for.

Saturated and unsaturated polymers

Saturated polymers have only single bonds in the main chain and are resistant to ageing, while unsaturated polymers contain double bonds in the main chain and are easier to crosslink; EPDM is a speciality because its double bond is in the side chain.

CR: Chloroprene rubber

Chloroprene rubber (CR) is a versatile, weather- and flame-resistant elastomer that is often used for seals, hoses and technical components for indoor and outdoor use and is also known as neoprene.

IRHD hardness (International Rubber Hardness Degree / ball indentation hardness)

IRHD hardness is an internationally standardised method for measuring rubber hardness using ball pressure and is particularly suitable for small or sensitive elastomer components.

Sealed seats

Sealing seats are machined contact surfaces that accommodate seals in a form-fit and force-fit manner, thus ensuring permanent media separation protection.

Valve seal

A valve seal is an elastic component that reliably seals the flow of gases or liquids in a valve. The seal prevents leaks, compensates for pressure and temperature changes and ensures that the valve fulfils its switching, control or shut-off function reliably and permanently.