Technicals

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Chemical Name Nitrile / NBR /
Buna-N
Ethylene  Propylene / EPDM Silicon / VMQ / PVMQ Neoprene Natural Rubber  SBR Fluorocarbon / Viton® Hydrogenated Nitrile / HNBR Isobutylene Isoprene / Butyl Fluorosilicone Urethane / Polyutrethane
ASTM D 1418 NBR EPDM VMQ CR NR SBR FKM HNBR IIR FVMQ AU
ASTM D2000 / SAE J 2000 BF, BG, BK, CH BA, CA, DA FC, FE, GE BC, BE AA AA, BA HK DH AA, BA FK BG
Durometer Range (Shore A) 20-95 30-90 30-90 20-95 20-100 30-100 50-95 50-90 40-90 50-80 35-100
ISO/DIN 1629 NBR EPDM VMQ CR NR SBR FPM HNBR IIR FVMQ AU
Maximum Elongation (%) 600 600 700 600 700 600 300 350 850 300 750
Temperature Range °C -40°C to 121°C -51°C to 149°C -73°C to 232°C -46°C to 121°C -51°C to 79°C -46°C to 107°C -32°C to 204°C -34°C to 166°C -51°C to 121°C -73°C to 202°C -34°C to 79°C
Temperature Range °F -40°F to 250°F -60°F to 300°F -100°F to 450°F -50°F to 250°F -60°F to 175°F -50°F to 225°F -25°F to 400°F -30°F to 330°F -60°F to 250°F -100°F to 395°F -30°F to 175°F
Tensile Strength (PSI) 200-3000 500-3000 200-1500 500-3000 500-3500 500-3000 1450 1500-3500 500-3000 500-800 500-6000
Abrasion Resistance Excellent Good Fair Excellent  Excellent Excellent Very Good Very Good Fair Poor Excellent
Compression Set Good Good Fair Very Good Excellent Good Very Good Very Good Good Very Good Good
Economical Price Low Low Medium High Low Low High High Medium High High
Electrical Resistance Good Very Good Excellent Fair Very Good Good Good Good Excellent Excellent Good
Flame Resistance Poor Poor Good Excellent Poor Poor Very Good Poor Poor Very Good Fair
Heat Resistance Good Excellent Excellent Good Good Good Excellent Very Good Good Excellent Good
Low Temperature Resistance Very Good Excellent Excellent Fair Very Good Fair Very Good Very Good Excellent Excellent Very Good
Metal Adhesion Very Good Fair Good Very Good Excellent Excellent Excellent Very Good Good Fair Good
Oil/Grease Resistance Very Good Poor Fair Excellent Poor Poor Excellent Excellent Fair Good Very Good
Ozone Resistance Fair Excellent Excellent Very Good Poor Poor Excellent Very Good Excellent Excellent Excellent
Permeability to Gases Very Good Very Good Poor Good Fair Good Good Good Excellent Poor Good
Rebound Good Good Good Excellent  Excellent Good Very Good Good Fair Very Good Good
Solvent Resistance Very Good Poor Poor Fair Poor Poor Excellent Poor Fair Fair Poor
Tear Resistance Good Fair Poor Good Excellent Good Good Very Good Good Poor Excellent
Water Resistance Good Excellent Very Good Very Good Good Very Good Poor Excellent Excellent Good Good
Weather/Sunlight Resistance Fair Excellent Excellent Excellent Poor Poor Excellent Very Good Excellent Excellent Excellent
Applications Molded shapes
Rubber-to-metal bonded components
Rubber connectors
Gaskets
Seals
O-rings
Carburetor and fuel pump diaphragms
Fuel systems
Hydraulic hoses
Tubing
Gaskets, bumpers, auto parts, auto brake systems, electrical installation, dust covers, weather stripping and conveyor belts Gaskets, seals, o-rings, and bellows. Refrigeration seals, Freon/air conditioning, motor mounts, engine coolants, petroleum and chemical tank linings, automotive gaskets and seals, and weather stripping. Tires, tubing, gaskets, belts, hoses, seals, shock mounts, rolls, vibration isolators, electrical components, bumpers, and drive wheels. Tire, tubes, gaskets, belts, hoses, seals, shock mounts, skirtboard rubber, lining rubber, and conveyor belt covers - ? Car and airplane seals and hoses
Fire-resistant coverings
Heat-resistant insulators
O-rings, shaft seals
Gaskets, fuel hoses, valve-stem seals 
Vehicle tubing, seals, cables and profiles Seals for vacuum applications, tire inner liners and inner tubes, hydraulics applications where synthetic fluids are used. Seals, o-rings, shock mounts, isolators, and diaphragms. Wearing surfaces of wheels and rollers
• power transmission elements
• seals
• soles
* Viton® are registered trademarks of DuPont.                    
Sr. No.  Nitrile / NBR /
Buna-N
Ethylene / Propylene / EPDM Silicon / VMQ / PVMQ Neoprene Natural Rubber  SBR Fluorocarbon / Viton® Hydrogenated Nitrile / HNBR Isobutylene Isoprene / Butyl Fluorosilicone Urethane / Polyutrethane
1 Excellent solution for sealing applications Exceptionally good resistance to weather aging, ozone, UV exposure.
 Broad temperature range and is generally odorless / non-toxic Good resistance to moderate exposure to ozone, sunlight, oxidation, weather, oils, gasoline, greases, solvents, petroleum oils, animal and vegetable oils, compression set, silicone oil, refrigerants, ammonia, carbon dioxide, water, and steam Excellent tensile, elongation,  resilience, and electrical insulation Superior water resistance, heat resistance, abrasion resistance. Excellent heat and chemical resistance. Outstanding heat and oil resistance.  Butyl should be used when the gases in a system or container cannot be allowed
to pass through the rubber molded part.
Excellent extreme temperature properties Strong resistance to abrasion and capable of sustaining repeated
high load cycles without failure.
2 Good compression set.
Resistance to heat, abrasion, gas pemeability
Water Resistant, Heat Resistant, phosphate ester base hydraulic fluids (Skydrol, Fyrquel, Pydraul), dilute acids, electrical insulation Resistant. Excellent resistance to high temperatures, ozone, oxygen, UV light, moisture, and fungus. Flame resistant and will not support combustion. Excellent compression set. Good electrical insulation, alcohol resistance, oxygenated solvent resistance, and mild acid resistance Excellent oxygen, ozone and weather resistance  Similar to NBR
but with
improved
chemical
resistance and
higher service
temperature
Excellent resistance to oxygenated solvents (ketones and alcohols), alkalis, flexing, and abrasion Excellent compression set resistance Good weather and oil resistance
3 Good rebound. EPDM’s dynamic and mechanical properties are, in general, between natural rubber and SBR Excellent vibration damping and maintains its dielectric strength Resilience and abrasion strength are good Good flexing qualities at low temperatures Successfully bonded to a wide range of materials Good compression set resistance Better wear and abrasion resistance over standard Nitrile. Capable of providing high energy absorption (damping) and thus has excellent electrical isolation performance Very clean, low odor and taste Affordable manufacturing process
4 Cheaper than fluoroelastomers Good low temperature flexibility Low compression set and offers good fatigue resistance, flex resistance, and elongation.  Adhesion to metals and fabrics is very good.  Excellent Tear Resistance Low-temperature flexibility, and heat aging properties Incombustible  Larger temperature range than NBR. Good resistance to sunlight, ozone, heat aging, animal and vegetable oils, oxidizing chemicals, silicone fluids and greases, ammonia, hydrazine, and phosphate ester type hydraulic fluids  Excellent electric, wheather & heat resitance -
* Viton® are registered trademarks of DuPont.                  
Sr. No. Nitrile / NBR /
Buna-N
Ethylene / Propylene / EPDM Silicon / VMQ / PVMQ Neoprene Natural Rubber  SBR Fluorocarbon / Viton® Hydrogenated Nitrile / HNBR Isobutylene Isoprene / Butyl Fluorosilicone Urethane / Polyutrethane
1 Poor Ozone, sunlight & weather resistant EPDM is not recommended for use with petroleum oils, fluids, or solvents because significant swelling would result.  Poor tensile, tear and abrasion resistance, and is not recommended for use in dynamic applications The cost of neoprene is its greatest disadvantage Deteriorates when exposed to oils, fuels, solvents, petroleum derivatives, and hydraulic fluids Poor resistance to oils, fuels, hydraulic fluids, strong acids, greases, fat, and most hydrocarbons. Relatively poor mechanical properties

The tensile strength decreases substantially at elevated temperatures
Attacked by Ozone, ketones,
esters, aldehydes,
chlorinated and
nitro
hydrocarbons 
Difficult to handle during manufacturing because of its tendency to trap air, blister, and creep Not good for dynamic seals due to friction properties and poor abrasion resistance Poor Heat resistance
2 Limited High temperature resistant Poor resistance to aromatic hydrocarbons (e.g., Benzol, Toloul) and aliphatic hydrocarbons (e.g., kerosene, turpentine) Poor resistance to most concentrated solvents, concentrated acids, concentrated alkalines, oils, fuels, hydrocarbons, and steam Poor resistance to strong oxidizing acids, esters, ketones, chlorinated, aromatic, and nitro hydrocarbons.  Poor resistance to sunlight, oxygen, ozone, and high temperatures Without special additives, SBR is vulnerable to ozone, oxygen and sunlight Limited elasticity at low temperatures & High Price  Increased cold flow with hydrogenation
Decreased elasticity at low temperatures with hydrogenation over standard nitrile
Poor cold flow characteristics and flame resistance
 Poor resistance to aromatic hydrocarbons (e.g., Benzol, Toloul), aliphatic hydrocarbons (e.g., kerosene, turpentine), coal,
Poor resistance to aromatic hydrocarbons (e.g., Benzol, Toloul), aliphatic hydrocarbons (e.g., kerosene, turpentine), coal, tar, and diester-based lubricants
Cost is substantially higher. Poor resistance to water.
Poor high temperature capabilities
* Viton® are registered trademarks of DuPont.                  

Which type of molding process is right for your application?

There are a number of factors to consider when determining the type of molding process required. Some of these include:

  • The size and geometry of your part
  • The weight of your part
  • The Material required
  • The volume of parts required

Whether your parts require commercial or precision tolerances we offer our customers cost effective molded rubber solutions.


Rubber Moulding

Rubber Moulding is a process by which rubber components, commercial rubber products and specialist custom rubber products are created. The rubber moulding process can be done in three ways:

  • Compression Rubber Moulding
  • Injection Rubber Moulding
  • Transfer Rubber Moulding.

Rubber Compression Molding

Compression Moulding is a method of moulding in which the preheated moulding material is first placed in an open, heated mould cavity. It is ideal for low to medium production volumes and is a particularly useful molding process for molding gaskets, seals, O-rings, and large, bulky parts.

Processes

  • Molding compound is placed in an open, heated mold cavity.
  • The mold is closed and pressure is then applied to force the material to fill up the entire mold cavity.
  • When the cavity is filled, excess material spills out into overflow grooves. Then the rubber is demolded, & the final molded rubber product is produced.

Advantages

  • Ideal process for low production volumes.
  • Maximized cavity count.
  • Economical process for medium precision.

Disadvantages

  • Greater Waste
  • Higher labour Cost
  • Not suitable for complex moulds
  • Difficult to control flash

Rubber Transfer Molding

Transfer Moulding combines the advantages of injection molding with the ease of compression molding. Rubber transfer molding is an ideal process for molding parts that require multiple cavities, intricate parts that require a closed mold, bonding rubber to metal parts and if the geometry of the part might cause mold cavities to trap air.

Processes

  • The pre-heated, uncured molding compound is placed in the transfer pot.
  • A hydraulically powered plunger pushes the molding compound through the sprue(s) into the pre-heated mold cavity. The mold remains closed until the material inside is cured or cooled.
  • The mold is split to free the product, with the help of the ejector pins.
  • The flash and sprue material is trimmed off.

Advantages

  • Product consistency better than compression molding, allowing tighter tolerance and more intricate parts
  • Production speed higher than compression molding
  • Fast setup time and lower setup costs than injection molding
  • Lower maintenance costs than injection molding
  • Ideal for Rubber to metal bounding parts
  • Ideal for moulding article with complex geometry that it eliminate trapped air

Disadvantages

  • Wastes more material than compression molding cause increase weight due to flash pad which remains in the pot after transfer moulding & has to be discarded.
  • Production speed lower than injection molding
  • Expensive tool cost than compression moulding

Rubber Injection Molding

Injection molding is considered to be the most important process for rubber moulded products. It is preferred over transfer moulding & compression moulding especially if the large volume production is required. This process was originally developed for the manufacture of thermoplastic materials. Processing with this equipment for rubber parts has been possible by adjusting plastification units, especially to the temperature controls of screw & plunger cylinder. It is an ideal process for large shot weights, high volumes of small to medium size parts, incorporating bonded inserts, achieving close dimensional tolerances, and making components that require uniformity or consistency of colour.

Processes

  • Uncured rubber is extracted into the machine using a screw feeder system. The screw feeder takes in the exact amount (or shot size) of material needed to create the desired number of parts.
  • Rubber is fed from a hopper into a heated barrel, and the material is slowly pushed by a screw-type plunger into a heated chamber. Material is then preheated to a state that will allow material to flow through a gate and runner system to fill the desired cavities evenly.
  • The mold remains at a set temperature so it can solidify once it is filled.
  • When material has reached a cured state, the mold will open and parts can be removed manually or using a brush system to strip them off of the mold.

Advantages

  • Reduced cycle time
  • Flash less tooling
  • Economical process for high volumes of medium to high precision components
  • Capable of producing over molded components
  • Minimal material Waste

Disadvantages

  • Higher set-up costs
  • More expensive machinery & tooling
  • Small runs of parts can be costly