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Our Material:

Rubber are called resilient polymeric materials which are processed by vulcanisation.

For our products we prefere to use standard qualities. Depending on the requirements of our customers, for individual articles special materials are used.

Overview of our most popular varieties of rubber

VarietyBenefitsDisadvantages
NR
Natural Rubber
high static and dynamic strength
very low attenuation
very good compressin-set
very good behavior at low temperatures
low aging resistance
low ozone resistance
no oil resistance
SBR
Styrene Butadiene Rubber
Buna
better heat resistance than NR
moderate aging resistance
medium elasticity
good abrasion and wear properties
low ozone resistance
low oil resistance
NBR
Nitril Butadien Rubber
Nitrile, Perbunan
good resistance against petrol and oil
good comression-set
good dampin (rising with )
good abrasion and wear properties
moderate aging resistance
bad ozone
bad low-temperature performance
EPDM excellent heat and weathering behavior
high ozone resistance
very good behavior at low temperatures
resistant to aqueous chemicals
no oil resistance
CR
Chloroprene Rubber
Neoprene
Heat, weathering and ozone resistance better than NR and SBR
medium oil resistance
problematic processing
strong hardening at temperatures below 0°C
FPM
Fluoro-Rubber
Viton
extremely good resistance to:
Heat, chemicals, solvents, oil, fuel, weather
complex processing
bad low-temperature performance
high cost
VMQ
Silikone
extreme heat resistance
excellent low temperature behavior
complex processing
low strength

Typical material properties of rubber

Hardness

The hardness of rubber is usually is measured in "Shore", according to DIN 53505.

Into the sample a rounded needle is intruded against a spring force. The resistance to this penetration (in percent) gives the hardness. (Thus, the Shore hardness varies values only from 0 to 100).
An extremely soft material (with the theoretical hardness of zero Shore), has no opposition to the spring force. At 100 Shore, the needle can not not penetrate into the material, the spring is compressed to the maximum.

Depending on the needle form we distinguish between:

  •  Shore A    Needle with blunt end        soft materials (rubber)  
  •  Shore D    Needle with a sharp end    hard material (plastic)  

We mainly process materials from 35 to 90 Shore A.

Abrasion Resistance

The Abrasion Resistance of rubber can be measured according to DIN 53516. In this experimental arrangement, a sample is pressed against a rotating drum, which is coated with sandpaper. The quantity of material, which was removed in a certain time, serves as a measure for Abrasion Resistance.

Therefore the value is given as: Abrasion Resistance according to DIN 53516: ### mm³

The normal values are 120 mm³ (very good) to 600 mm³ (unsatisfactory)

The value of the abrasion resistance decreases with increasing hardness, softer rubber grades have a lower abrasion resistance than harder types.

For information about life time of a component this value for abrasion resistance must not be considered alone. Especially for freely rotating rollers other properties of the rubber (surface aging, elasticity, ...) have much more influence on the achievable life time.

Frictional index µ0

For elastomers, the classical laws of solid friction is not valid, or only with strong restrictions. The reason is that rubber has no rigid surface, but depending on the hardness and creep the rubber adjusts with the surface of its counterpart.

Therefore no certain value for frictional index (e.g. rubber / steel) can be specified, but must always be determined by experiments adjusted to the practical case.

Generally this: The higher the hardness and the better the abrasion value, the lower the friction.

Tensile strength, Elongation at Break, Modulus of Elasticity

Tensile Strength and Elongation at Break can be determined by means of Tensile Test according to DIN 53504.

The Tensile Strength of elastomers is significantly lower than that of solid materials. It is approximately 5 - 20 N/mm²

The Elongation at Break depends strongly on the hardness of the material and is approximately 100% - 800%


The Modulus of Elasticity E is the ratio of Stress σ to Strain ε and is determined by evaluating the Tensile Test. In the stress-strain diagram the Modulus of Elasticity is the increase of the read line graph.

For metals, the Modulus of Elasticity (at small deformations) is a constant value. Hooks Law can bee applied: σ = E × ε

For rubber, however, the stress-strain diagram is a curved line. Therefore no general value for the Modulus of Elasticity can be specified.

Often used as a measure of Elasticity is the stress value at 300% (100% for hard materials) elongation: Modulus 300 σ300

Compressive strength and shear strength, shear modulus

The allowable stresses in compression and shear can be derived from the shear modulus.

There are different methods by which one can derive the 
shear modulus G [N / mm] from the Shore hardness H [Sh A] in a simple way.

Battermann and Köhler specify the following relationship: G = 0,086 × 1.045H

The allowable strength limit can be specified only with difficulty. 
It is useful to indicate the limit of strain according to the type of load: 
elastic compressive strain <15% 
elastic shear strain <30%

Dipl.-Ing. Alexander Kubai

Linzer Str. 70
4780 Schärding

Phone +43 7712 2058
Fax +43 7712 4478

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