Raw material is the strong base upon which your product is built. Therefore, choosing the right material becomes all the more important when you’re manufacturing quality products. We wrote this post in the effort that anyone who’s just starting out in the manufacturing sector isn’t left in the lurch when it comes to choosing the right rubber material for their products.

What is a rubber compound?

Rubber is the end product resulting from various monomer units combining to become polymers with the help of vulcanization. The base monomer is used to distinguish the types of rubber, for example: Nitrile, Silicone etc.

This elastomer cannot be used as is to manufacture rubber products because of its poor tensile strength— it has low tensile strength and cannot be used for industrial products which usually require higher tensile strength. 

 

Rubber compounds are made of many different ingredients like the base elastomer, vulcanization agents, fillers and plasticizers. When subjected to heat, the long and flexible chains of rubber react with vulcanizing/curing agents like Sulphur to form three-dimensional structures. It is easier to enhance the physical properties once the rubber is cured. Also, the compound does not deteriorate easily.

Things to consider before choosing your rubber material

All rubber components are useful and unique in their own way, however, not all of them can be used for a specific purpose. Hence, it becomes imperative to ask the right questions that lead to the right material for your product. Here are some questions to consider:

 

• What am I going to be using this rubber part in?

The knowledge of the end-use application of the part is very important while choosing the base material.

Is it going to be used for sealing? Will it transmit energy? Is it going to pass some liquid through it?

The outcome of this question will enable you to narrow down your answers to a few rubber materials. Now, onto the next question.

• What is the temperature that the part is going to be exposed to?

Is it going to be under constant temperature, or are they going to be maximum and minimum temperature requirements? Different rubber materials behave differently in different temperatures. 

• What are the other physical properties that the product should have?

Compression set, elongation, hardness, etc. and other factors from the end product will help you zero in on the perfect raw material.

• Are there any regulatory requirements?

Many food and water processing equipment use rubber gaskets for sealing. These are required to be FDA approved. Likewise, there are many other regulatory approvals that you need to consider. For example, we at Victory Seals supply sealing gaskets to water purifier manufacturing companies. We have to ensure that our products are food grade and approved by the FDA before passing it on to the customer. 

• Is the part being exposed to chemicals?

You also need to factor in if the end part is going to be exposed to acids, oils or bases, and also the amount of exposure. 

Types of rubber compounds

 

Now that you have listed down the ideal properties of the end part, let’s have a look at some of the widely used and well-known rubber compounds and their properties.

EPDM 

EPDM is the most versatile and commonly used rubber compound. 

 

Some key properties/ features of EPDM:

• Hardness range: 50-90 Shore A
• Temperature range: -40°F up to +250°F
• Tensile range: 500-2500 psi
• Excellent resistance to sun, water, ozone, and oxidation

 

Limitations of EPDM rubber:

• Cannot be used in applications involving continual contact with hydrocarbon based products & oils such as gasoline, kerosene, concentrated acids etc.

 

Applications of EPDM: 

• EPDM can be used for O-rings, gaskets etc. 
• It is widely used in outdoor roofing, electrical insulation, water appliances, automotive brake systems, automobile cooling systems etc.
• EPDM is a cheaper alternative to Silicone

 

Silicone 

Are you looking for a material that can withstand HIGH temperatures? Silicone is your answer.

 

Some key properties/ features of Silicone rubber:

• Hardness range: 20-90 Shore A
• Temperature range: as low as -60° to -150°F & up to 450°F
• Tensile range: 200-1500 psi
• Excellent resistance to temperature, water, flame

 

Limitations of Silicone rubber:

• Poor resistance to wear and abrasion. Therefore, it is better suited for static applications.
• Silicones are not suited in the presence of most concentrated solvents, oils, acids and dilute sodium hydroxide.

 

Applications of Silicone rubber: 

• Silicone is used for O-rings, oil seals, gaskets etc. that need to withstand extreme temperatures. 
• Oven doors, HVAC applications, circuit boards, for vibration dampening in automotive shaft applications etc. 
• It is also used in the manufacture of space suits.

 

Fluorocarbon/ Viton®

Viton® is a registered trademark and brand name under DuPont Performance Elastomers. 

 

Some key properties of Viton are:

• Hardness range: 50-90 Shore A
• Temperature range: -15°F to +450°F
• Tensile range: 500-2000 psi
• Resistance to oil, sunlight, tear, abrasion, and solvent

 

Limitations of Viton:

• Viton is not recommended for applications requiring good low temperature flexibility.

 

Applications of Viton: 

• Viton is used in high temperature, low compression set applications. 
• As they are compatible with most chemicals and oils, they’re used in fuel injection seals, O-rings used in oil reservoirs etc.

Nitrile Rubber (NBR)

Nitrile Rubber/ NBR/ Buna N is a favorite for sealing applications, owing to its good adhesion to metals and resistance to gasoline and oils.

 

Some key properties/ features of NBR:

• Hardness range: 40-95 Shore A
• Temperature range: -40°F up to +250°F
• Tensile range: 200-3000 psi
• Excellent resistance to oil, water, wear & tear, abrasion

 

Limitations of Nitrile rubber:

• Cannot be used in applications involving polar organic solvents, ozone, sunlight
• Poor flame resistance

 

Applications of NBR: 

• Usual suspects like O-rings, oil seals, gaskets etc.
• Nitrile tubing, automotive parts, transmission belts, hydraulic hoses, fuel systems etc.

 

Nitrile Hydrogenated (HNBR)

 

HNBR is produced by hydrogenation of nitrile and which enhances the resistance to oils, temperature and ozone.

 

Some key properties/ features of HNBR:

• Hardness range: 50-90 Shore A
• Temperature range: -40°F up to +300°F
• Tensile range: 200-3000 psi
• Excellent resistance to oil, water, wear & tear, abrasion

 

Limitations of Hydrogenated Nitrile rubber:

• Cannot be used in applications involving polar organic solvents, chlorinated hydrocarbons
• Poor flame resistance

 

Applications of HNBR: 

• O-rings, oil seals, gaskets etc.
• Automotive applications, gearbox, fuel systems, industrial applications etc

 

Natural Rubber (NR)

 

Natural rubber is vulcanized product from the sap of rubber trees(latex). 

 

Some key properties of NR are:

• Hardness range: 50-90 Shore A
• Temperature range: -50°F to +200°F
• Tensile range: 500-3500 psi
• Resistance to tear and abrasion
• Excellent adhesion to metals

 

Limitations of Natural Rubber:

• NR is not recommended for applications where the parts are exposed to oil and ozone.

 

Applications of Natural Rubber: 

 

• Seals, gaskets, insulators, etc.
• Used in low compression set applications. 
• Due to high tear and abrasion resistance, parts are used in dampeners, vibrations mounts

 

Polyacrylate (ACM)

 

Polyacrylate rubber consists of a polymerized ester and a curing monomer.

 

Some key properties of ACM are:

• Hardness range: 50-90 Shore A
• Temperature range: -30°F to +300°F
• Tensile range: 500-2500 psi
• Resistance to oil and ozone at high temperature.

 

Limitations of Polyacrylate:

• Not recommended for applications where the parts are exposed to alcohol, chlorinated hydrocarbons, hot water.

 

Applications of Natural Rubber: 

 

• Seals, gaskets, etc.
• Used in automotive applications. 

 

Neoprene (Chloroprene- CR)

 

Some key properties of CR are:

• Hardness range: 40-90 Shore A
• Temperature range: -40°F to +250°F
• Tensile range: 500-3000 psi
• Good resistance to oils, ozone and heat aging

 

Limitations of Chloroprene Rubber:

• Cannot be used in applications involving polar organic solvents (esters, ethers, ketones), chlorinated hydrocarbons

 

Applications of Chloroprene Rubber: 

 

• Seals, gaskets, O-rings, etc.
• Used in automotive and construction industry. 
• Due to good resilience and toughness Neoprene parts are used in dampeners, vibration pads, shock absorber seals and transmission belts.