Characteristics and inspection of elastomers
One of the most often named properties regarding Polymer materials is hardness. Even so the values can be quite misleading. Hardness is the resistance of a body against penetration of an even harder body – of a standard shape defined pressure. There are two procedures for hardness tests regarding test samples and finished parts made out of elastomer material:
1. Shore A/D according to ISO 48 / DIN 53 505 / ASTM D 2240 Measurement for test samples
2. Durometer IRHD (International Rubber Hardness Degree) according to ISO 48 / DIN 53 519-1 and -2 / ASTM 1414 and 1415
Measurement of test samples and finished parts
The hardness scale has a range of 0 (softest) to 100 (hardest). The measured values depend on the elastic qualities of the elastomers, especially on the tensile strength. The test should be carried out at temperatures of 23 ±2 °C – not earlier than 16 hours after the last vulcanisation process (manufacturing stage). If other temperatures are being used this should be mentioned in the test report. Tests should only be carried out with samples which have not been previously stressed mechanically.


Silicone rubber is an elastomer (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 are often one- or two-part polymers, and may contain fillers to improve properties or reduce cost. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures from -67 °F to 572 °F (-55 °C to 300 °C) while still maintaining its useful properties. Due to these properties and its ease of manufacturing and shaping, silicone rubber can be found in a wide variety of products, including: voltage line insulators, automotive applications; cooking, baking, and food storage products; apparel such as undergarments, sportswear, and footwear; electronics; medical devices and implants; and in home repair and hardware with products such as silicone sealants.
Common Name: Silicone
ASTM D-2000 Classification: FC, FE, GE
Chemical Definition: Polysiloxane
Temperature Range
Low Temperature Usage: -60° to -150° F | -50°C to -100°C
High Temperature Usage: Up to 480° F | Up to 250°C
Industrial Classifications
Liquid Silicone Rubbers (LSR) - also called heat curable liquid materials. Processed on specially designed injection molding and extrusion equipment.
High Temperature Vulcanizing (HTV) - also called heat curable silicone, these materials usually are in a semi-solid gum form while in the uncured state. Rubber-type processing is required to produce finished items.
Room Temperature Vulcanizing (RTV) - usually comes in the form of a flowable liquid. Commonly used for sealants, mold making, encapsulation and potting. RTV materials are generally not used as conventional rubbers.

About Liquid Silicone Rubber (LSR)

Liquid silicone rubber (LSR) and silicone rubber are extraordinary manufactured materials. By combining the appropriate additives, in the correct amounts, silicone is transformed into a highly specific material.
It can insulate. Or it can be conductive.
Silicone can withstand freezing temperatures. And it can stand up to high heat.
It can be translucent. It can also be almost any color - even glow-in-the-dark green.
Silicone resists fungus. At the same time, it is non-toxic.
From the cleanroom to the operating room, from the dashboard to the circuit board, silicone rubber exhibits such a wide range of properties, it is used in many applications where organic rubber cannot perform.

Silicone Compounds

Silicone rubber material can be compounded in different ways to meet any number of applications. Silicone fillers can also improve the tensile strength to be in the area of 1500 PSA and tear resistance up to 200lbs. Flame retardant additives can be added to increase fire resistant properties. Carbon black additive will also increase the silicone's electrical conductivity. Silicone is a very clean rubber with low odor and taste. In addition to temperature resistance, other advantages of silicone rubber include insulation from electricity, compression set resistance, and the ability to repel water. Because of these advantages, silicone rubber is a versatile material for many industries Custom silicone rubber parts can be used in the production of: Extruded rubber products
Rubber seals and tubing
Rubber gaskets
Molded rubber products


FKM (by ASTM D1418 standard) (equivalent to FPM by ISO/DIN 1629 standard) is the designation for about 80% of fluoroelastomers as defined in ASTM D1418. All FKMs contain vinylidene fluoride as a monomer.  Fluoroelastomers are more expensive than neoprene or nitrile rubber elastomers. They provide additional heat and chemical resistance. FKMs can be divided into different classes on the basis of either their chemical composition, their fluorine content or their crosslinking mechanism.
On the basis of their chemical composition FKMs can be divided into the following types:
Type 1 FKMs are composed of vinylidene fluoride (VDF) and hexafluoropropylene (HFP). Copolymers are the standard type of FKMs showing a good overall performance. Their fluorine content typically ranges around 66 weight percent.
Type 2 FKMs are composed of VDF, HFP, and tetrafluoroethylene (TFE). Terpolymers have a higher fluorine content compared to copolymers (typically between 68 and 69 weight percent fluorine), which results in better chemical and heat resistance. Compression set and low temperature flexibility may be affected negatively.
Type 3 FKMs are composed of VDF, TFE, and perfluoromethylvinylether (PMVE). The addition of PMVE provides better low temperature flexibility compared to copolymers and terpolymers. Typically the fluorine content of type 3 FKMs ranges from 62 to 68 weight percent.
Type 4 FKMs are composed of propylene, TFE, and VDF. While base resistance is increased in type 4 FKMs, their swelling properties especially in hydrocarbons are worsened. Typically they have a fluorine content of about 67 weight percent.
Type 5 FKMs are composed of VDF, HFP, TFE, PMVE, and Ethylene. Type 5 FKM is known for base resistance and high temperature hydrogen sulfide resistance.

FKM advantages

Excellent temperature resistance
High chemical stability
Good weather, aging and oxygen stability
Excellent resistance in mineral oils and fats
Low gas permeability
Very good resistance in non-polar media
Temperature range from –40 °C to +225 °C

Chemical Resistance and Stability

The chemical resistance and high temperature stability is due to the bulkiness of the fluorine atoms, shielding the polymer backbone and carbon-fluor bond from attack, and the high bonding energy of the carbon-fluor bond, as illustrated in the following figures.

Fkm temperature range

The typical service temperature of FKMs is between -20°C (-5°F) and +230°C (+445°F). They can, however, withstand temperatures up to 300°C for a short period of time.
Hardness (Shore A): 55 to 90.

FKM Applications

FKM provides premium, long-term reliability even in harsh environments. A list of its applications is given below:
Aerospace: O-ring seals in fuels, lubricants, Valve stem seals, Fuel hoses, Fuel Injector O-rings, In tank and quick connect, Flue duct exp. Joints, Valve liners, Roll covers, Sheet stock/cut gaskets etc.
Automotive: Shaft seals, Check valve balls, Diaphragms, Military flare binders, Electrical connectors, Tire valve stem seals, Clips for jet engines, Lathe cut gaskets etc.
Industrial: Hydraulic o-ring seals and hydraulic systems, Manifold gaskets, Fuel tank bladders, Firewall seals, Engine lube siphon hose fuel system seals, Gaskets (valve & manifold) etc.

Fkm products manufactured by us

1. o-rings
2. seals
3. gaskets
4. quad ring seals
Any customized products


We at horiaki india pvt ltd , have vast expertise and experience in manufacturing thermoplastic polyurethanes i.e., TPU as elastomers for products like polyurethane dampers and bearings and bushes.
WHAT are polyurethanes?
Polyurethanes are formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. Because a variety of diisocyanates and a wide range of polyols can be used to produce polyurethane, a broad spectrum of materials can be produced to meet the needs of specific applications.

Types of Polyurethane:

Flexible Polyurethane Foam
Flexible polyurethane foam is used as cushioning for a variety of consumer and commercial products, including bedding, furniture, automotive interiors, carpet underlay and packaging. Flexible foam can be created in almost any variety of shapes and firmness. It is light, durable, supportive and comfortable.
Flexible polyurethane foam accounts for about 30 percent of the entire North American polyurethane market, and is used largely for bedding, furniture and in the automotive industry.
Rigid Polyurethane Foam
Rigid polyurethane and polyisocyanurate (polyiso) foams create one of the world's most popular, energy-efficient and versatile insulations. These foams can significantly cut energy costs while making commercial and residential properties more efficient and comfortable.
According to the U.S. Department of Energy, heating and cooling account for about 56 percent of the energy use in a typical U.S. home, making it the largest energy expense for most homes. To maintain uniform temperature and lower noise levels in homes and commercial properties, builders turn to rigid polyurethane and polyisocyanurate foam. These foams are effective insulation materials that can be used in roof and wall insulation, insulated windows, doors and air barrier sealants.

Coatings, Adhesives, Sealants and Elastomers (CASE)

The uses of polyurethanes in the coatings, adhesives, sealants and elastomers (CASE) market offer a broad and growing spectrum of applications and benefits. Polyurethane coatings can enhance a product’s appearance and lengthen its lifespan. Polyurethane adhesives can provide strong bonding advantages, while polyurethane sealants provide tighter seals. Polyurethane elastomers can be molded into almost any shape, are lighter than metal, offer superior stress recovery and can be resistant to many environmental factors.

Thermoplastic polyurethane (TPU)

Thermoplastic polyurethane (TPU) offers a myriad of physical property combinations and processing applications. It is highly elastic, flexible and resistant to abrasion, impact and weather. TPUs can be colored or fabricated in a wide variety of methods and their use can increase a product's overall durability.
TPU is an elastomer that is fully thermoplastic. Like all thermoplastic elastomers, TPU is elastic and melt-processable. In addition, it can be processed on extrusion, injection, blow and compression molding equipment. It can be vacuum-formed or solution-coated and is well suited for a wide variety of fabrication methodologies. TPU can provide a considerable number of physical property combinations, making it an extremely flexible material adaptable to dozens of uses such as construction, automotive and footwear.

Reaction Injection Molding (RIM)

Car bumpers, electrical housing panels and computer and telecommunication equipment enclosures are some of the parts produced with polyurethanes using reaction injection molding (RIM). Adding design flexibility, the polyurethane RIM process produces parts that are usually not achievable using typical injection molding processes, such as thick- and thin-walled parts, encapsulated inners and foamed cores. In addition to high strength and low weight, polyurethane RIM parts can exhibit heat resistance, thermal insulation, dimensional stability and a high level of dynamic properties. Automotive, construction, appliance, furniture and recreation and sporting goods are a few of the markets and applications using RIM technology.


Polyurethane binders are used to adhere numerous types of particles and fibers to each other. Their primary areas of use are in the manufacturing of wood panels, rubber or elastomeric flooring surfaces and sand casting for the foundry industry. The highest volume application for polyurethane binders is in the manufacture of Oriented Strand Board (OSB). These wood panels are used in structural sheathing and flooring, manufactured housing, joists and beams and shop panels. Rebond carpet underlay uses polyurethane binders to adhere scrap pieces of foam, which are often flexible polyurethane foam, together in its production.

Waterborne Polyurethane Dispersions (PUDs)

Waterborne polyurethane dispersions (PUDs) are coatings and adhesives that use water as the primary solvent. With increasing federal regulation on the amount of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) that can be emitted into the atmosphere, PUDs are being used in more industrial and commercial applications.


Vibration damping is an important part of building machines or working factories. When you’re talking about situations in which there are lots of moving parts and lots of friction, you definitely need to be able to control vibrations. Excess vibrations can create unnecessary noise, break a machine’s moving parts down more quickly, or even cause the machine to come apart of stop working sooner rather than later.
There are many different ways to control vibration. One is to simply absorb it. This is a process known as vibration damping.


What is FFKM?
FFKM, or perfluoroelastomer, contains higher amounts of fluorine than standard FKM, and features higher temperature ratings, up to approximately 325°C. FFKM also has improved chemical resistance, with nearly universal chemical compatibility. This combination of high-performance capabilities makes FFKM seals the premium choice for the most challenging applications.
The first commercially available FFKM seal was produced in the late 1960s. However, widespread manufacturing of FFKM materials did not occur until the late 1980s due to patent restrictions.
FFKM is used in o-rings and seals in environments with high temperatures and/or harsh chemicals in the aerospace, semiconductor, energy, pharmaceutical and industrial industries.
FFKMs (by ASTM 1418 standard) (equivalent to FFPMs by ISO/DIN 1629 standard) are perfluoroelastomeric compounds containing an even higher amount of fluorine than FKM. They have further improved resistance to high temperatures[1] and chemicals and even withstand environments where Oxygen-Plasma are present for many hours. Certain grades have a maximum continuous service temperature of 327 °C (621 °F). They are commonly used to make O-rings and gaskets that are used in applications that involve contact with hydrocarbons or highly corrosive fluids, or when a wide range of temperatures is encountered.
For vacuum applications, demanding very low contamination (out-gassing and particle emission) as well as high temperature operation (200 - 300 °C) for prolonged out-baking or processing times and where a copper or metal sealing is not possible or very inconvenient/expensive, a custom-made, clean-room manufactured, sealing such as Kalrez® 9100, SCVBR or Perlast can be used. After manufacturing, they are O-plasma vacuum cleaned (and/or vacuum baked) to reach out-gassing performance similar to Teflon while reaching vacuum leak tightness (permeability rates) similar to FKM (Viton) compounds. This combination of properties allows FFKM seals to reach well into UHV pressures without the use of metal sealing. However, they are significantly more expensive than standard FKM O-rings.

What is FKM?

FKM is the ASTM designation for a class of fluorinated, carbon-based synthetic rubber, commonly known as fluoroelastomer. FKM has impressive heat resistance, allowing FKM seals to withstand temperatures greater than 200°C. FKM also exhibits extraordinary levels of resistance to high pressures, chemicals and other fluids (including several fuels).
FKM was originally developed in the late 1950s in response to demand for high performance seals in the aerospace industry. Development of FKMs continued through the 1980s, with advancements including greater thermal stability and improved heat, solvent, and compression resistance.
Today, FKM materials are commonly used to manufacture o-rings, seals, and gaskets for a variety of high-performance applications in the automotive, aerospace, energy, semiconductor, and industrial industries.

Why do we prefer FFKM over other material standards?

FKM vs. FFKM Comparison
See a comparison chart for other material compounds here.
FKM and FFKM Solutions by Greene, Tweed
Greene, Tweed offers a broad range of FKM and FFKM sealing solutions to meet the specific demands of the industries and applications we serve.
Greene, Tweed’s proprietary FFKM material, Chemraz®, has the broadest chemical resistance of any elastomeric material, combining the resilience and sealing force of an elastomer with chemical resistance approaching that of PTFE.
Chemraz® Perfluoroelastomers (FFKM)
Fluoroelastomers (FKM)


Estimated temperature range (°C/°F) -20 - 250 (-4 to 482) -40 - 325 (-40 to 617)
Heat resistance (ASTM D2000) (°C/°F) 225/437 (Type G) 250/462 (Type H)
Elongation @ break, % (ranges) 70 – 300 100 – 300
Compression set 15-25% (on 214 o-ring after 70 hr @ 200°C) 15-25% (on o-ring after 70 hr @ 200°C)
better at higher temperatures: 15-30%
(on o-ring after 70 hr @ 300°C)
Hardness range (Shore A) 60 to 95 65 to 95
Tensile strength range (psi/MPa) 1,500/1.03 to 4,500/3.10 1,250/8.61 to 3,600/24.8
Specific gravity 1.8 to 2.0 1.9 to 2.2
Fluorine content of polymer (%) 66 - 70% 71 - 73%
Chemical resistance Broad range of chemicals: ga-soline, alcohol, fuel additives, acids, hydrocarbons, water, oils, oxidation, ozone, radiation Broadest range of chemical resistance
Industry applications Aerospace
Semiconductor (dominant market)
Features Good wear resistance
Excellent compression set
Great heat resistance
Superior swell resistance in high octane and oxygenated fuels
Excellent thermal resistance
Excellent plasma resistance
Excellent chemical resistance
Superior compression set at elevated temperatures
Outstanding chemical compatibility
Not recommended for Ketones (MEK)
Low molecular weight esters and ethers
Nitro hydrocarbons
Hot hydrofluoric
Molten metals
Gaseous alkali metals
Halogenated freons/fluids
Uranium hexafluoride

Fluorosilicone (FVMQ/FVQM)

What is fluoro silicone?
The Fluorosilicone (FVMQ) is an elastomer whose characteristics are higher than those of the traditional silicone because some flour(in % respect to the polymer) is inside the mixture. Therefore it’s possible to enlarge considerably the fields of application of the moulded or extruded items to use them in variuos industrial sectors:
– Automotive
– Electric, electronical
– Oil, chemical
– Aviation and naval
Fluorosilicone O-Rings Features and Resistances:
Excellent flexibility and resistance to compression set
Excellent resistance to aging and weather-sunlight
Resistance to oxidizing chemicals, animal and vegetable oils, fuels, aromatic and chlorinated solvents
Resistant to diluted alkalies, diester oils, aliphatic and aromatic fluorocarbons, silicone oil, toluene, benzene, ozone and oxidative environments.
Fluorosilicone exhibits great resistance to oil and other hydrocarbons;
Fluorosilicone vs. Silicone
Fluorosilicone exhibits mechanical and physical characteristics very similar to silicone. Fluorosilicone offers greater fuel and oil resistance than silicone, but lower hot air resistance.

Fluorosilicone, Flourosilicone, Florosilicone? Fluorosilicone Rubber?

Occasionally flourosilicone or florosilicone is mistakenly used to specify fluorosilicone products. Fluorosilicone is the correct term and spelling. Fluorinated silicone rubber is a more technical term for fluorosilicone. Fluorosilicone rubber is a common term for fluorosilicone, which is a synthetic material, not made from natural rubber
Thermal Properties
Low Temperature Range - 85º F to - 70º F
Minimum for Continuous Use (Static) - 80º F
Brittle Point - 85º F
High Temperature Range + 400º F to + 450º F
Maximum for Continuous Use (Static) + 450º F


Fluorosilicone O rings are widely used elastomer seals that can meet a wide range of applications. The mechanical and physical properties are very similar to silicone rubber.
Fluorosilicone o rings offer improved fuels and mineral oil resistance but poor hot air resistance when compared with silicone. fluorosilicone o rings are commonly referred to as FVMQ orings. Fluorosilicone seals are widely used in semiconductor Ashing equipment for their resistance to oxygen plasma.


Fluorosilicone seals are often used in aerospace applications for fuel systems and systems requiring resistance to diester base lubricants to 175°C. Due to their poor physical characteristics they are normally only recommended for static applications.
fluorosilicone adhesives, sealants, gasketing, potting compounds protect against erosion/corrosion and withstand exposure to oils, fuels, solvents and other aggressive fluids. These products have good mechanical strength properties and bond well to many similar and dissimilar substrates. These include glass, silicone rubbers, stainless steel, titanium, aluminum and many plastics. Fluorosilicone elastomers feature enhanced performance capabilities. They also resist outdoor weathering, rigorous thermal cycling, have high elongation upon cure and exceptional high/low temperature serviceability.
Our products:
seals gaskets
quad rings
any customized products

Nitrile (Buna-N) Rubber Compound

Acrylonitrile Butadiene Rubber (NBR) or Nitrile rubber is one of the most popular compounds for automotive applications. It also is well known as Buna-N. This name came from one of the first base polymers patented in 1934, therefore people commonly use this name for all classes for Nitrile to this day.
NBR is the polymerization of Acrylonitrile (CH2=CHCN) and Butadiene (CH2CH-CH=CH2) into one large multiple-unit chains. The amount of Acrylonitrile is varied to provide different range of oil resistance the base polymer will have. Typical ranges are between 14 to 50 percent acrylonitrile.  As the Acrylonitrile increase the polymer will have greater oil and fuel resistance.  However, the rubber will have less flex at lower temperature.  The final compound will have a higher glass transition temperature.

The Pros And Cons Of Nitrile Rubber, NBR Or Buna-N

Nitrile, Buna-N or NBR rubber is a widely used elastomer, thanks in large part to its highly oil & fuel resistant properties and tensile strength. In this article, Martin’s Rubber Company explains more about the properties, applications, pros and cons of this versatile rubber material.   Nitrile rubber is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene that you may know better under trade names like Nipol, Krynac and Europrene N

NBR rubber properties

Nitrile is a family of unsaturated copolymers of 2-propenenitrile and butadiene monomers (1,2-butadiene and 1,3-butadiene). Its physical and chemical properties vary depending on the polymer’s composition of nitrile. The more nitrile there is within the polymer, the higher its resistance to oils but the lower its flexibility. Nitrile rubber is more resistant than natural rubber to oils and acids, and has superior strength, but suffers from inferior flexibility.

Where is nitrile used?

Nitrile rubber is used in a wide variety of applications, such as O-rings, gaskets, oil seals, automotive transmission belts, hoses, V belts, synthetic leather, disposable non-latex gloves, printer’s form rollers and cable jacketing. NBR latex can also be used in the preparation of adhesives or as a pigment binder.

Pros and cons of Buna-N

Nitrile offers the following advantages:
Excellent abrasion resistance.
Good rebound.
Good tear resistance.
Good non-polar solvent resistance.
Good water resistance.
Good oil resistance.
Cheaper than fluoroelastomers

Nitrile suffers from the following disadvantages:

Poor ozone, sunlight, and weather resistance.
Limited high temperature resistance.
Poor flame resistance.


Hydrogenated acrylonitrile butadiene rubber (HNBR) is a unique elastomer. It can be produced from conventional nitrile rubber by hydrogenation of the unsaturated bonds in the butadiene units of the polymer. The properties of hydrogenated nitrile rubber (HNBR) depend upon the acrylonitrile content and the degree of hydrogenation of the butadiene copolymer. HNBRs have better oil and chemical resistance than nitrile rubbers and can also withstand much higher temperatures. Like NBR, this type of elastomer has excellent resistance to oils and fuels but it also has excellent resistance to many chemicals, heat (steam / hot water) and ozone. The mechanical properties like tensile and tear strength, elongation, and abrasion resistance are also excellent. Furthermore, HNBRs have good dynamic behavior at elevated temperatures.


HNBR elastomers offer an excellent range of performance at a cost between nitrile rubber (NBRs) and (per)fluoroelastomers (FMKs). They fill the gap between these two elastomers in many areas of application where resistance to heat and aggressive media are required simultaneously. They are an excellent choice for applications where resistance to ozone and weathering, industrial lubricants, amine based corrosion inhibitors, sour gases (H2S), and  hot water / steam up to 150°C is required.
Typical applications include gaskets and seals, especially for the oil and gas industry, and accumulator bladders, and diaphragms.
The typical working temperature range is -25°C to +160°C

Automotive Industrial Specialised
A/C Seals and hoses Blow-out preventors High performance shoe soles
Engine seals, grommets and gaskets Chevron seals, also called Vee packing  
Fuel system seals and hoses Heat Exchanger gaskets  
Serpintine (multi-V) belts Oil field packers  
Suspension seals Paper mill rolls  
Synchronous (timing) belts Rotary shaft seals  
Transmission system bonded piston seals Steel mill rolls  

Our Products