What is the “Tensile Strength” of Rubber Conveyor Belt, and What Affects It?

When describing the specifications and models of rubber conveyor belts, we often encounter “Tensile Strength”, what does this mean? The tensile strength of the conveyor belt refers to the ultimate ability of the rubber covering layer to resist tensile damage, and refers to the load on the unit section when the test rubber part is stretched to break, also known as the breaking strength, the unit is MPa. The tensile strength index is generally used as the physical and mechanical performance standard of the rubber cover(both for top and bottom cover) of the conveyor belt, and together with the “elongation at break” (%) and “abrasion loss” (mm3), it is called the three main performance indicators of the rubber cover of the conveyor belt

Factors Affecting Tensile Strength

In the production process of the conveyor belt, the following factors will directly affect the tensile strength of the conveyor belt rubber:
1. The molecular weight of the rubber determines the tensile strength of the product. The larger the molecular weight, the better the tensile strength, and vice versa, the smaller the tensile strength.
2. The greater the cross-linking density of rubber, the greater the tensile strength.
3. The smaller the particles of the compounding agent are, the greater the tensile strength will be. Adding stearic acid and zinc oxide can increase the surface activity, so the tensile strength will increase accordingly. The more the compounding agent is used, the greater the tensile strength will be.
4. A softener is usually added to the formula for making rubber conveyor belts. If the amount of softener exceeds the standard, the tensile strength of the rubber will be reduced.
5. The mixing of rubbers will also increase the tensile strength. For example, the blending of nitrile rubber and PVC will increase the tensile strength.
6. The greater the molecular weight, the greater the tensile strength.
7. The rubber crystallinity of natural rubber, neoprene and butyl rubber is relatively high, so the tensile strength of these rubbers is also relatively large.

The tensile strength of the conveyor belt is one of its quality standards. The production process of the conveyor belt is numerous, and the production process is complex. Therefore, the factors affecting the tensile strength of the conveyor belt are also complicated. Factors so that you can conduct an organized analysis and make targeted control methods

How to test the tensile strength of conveyor belt cover?

This test is accomplished by placing a dumbbell shaped specimen into the grips, or jaws, of a tensiometer. The tensiometer pulls the grips apart steadily until the dumbbell breaks. The force at material rupture is known as ultimate tensile strength, which is commonly shortened to tensile strength or tensile.

Different countries have their own different requirements for tensile strength, at present, almost all conveyor belt manufacturers in the world market follow several internationally recognized rubber cover strength grade systems. Most countries follow the German DIN22102 class standard. Of course, there are also regional grading standards. For example, most countries in the United States are used to following the RMA grading standard. The country also has its own grading standards covering standards such as GB/T7984 in China, AS1332 in Australia, JISK6322 in Japan, BS-490 in the UK and SANS-1173 in South Africa.

Cover GradeCountryApplicable StandardsMin.Tensile
at Break(%)
ISO-LInternationalISO -1024715350200
ISO-HInternationalISO -1024724450120
ISO-DInternationalISO -1024718400100
AS-NAustralianAS -133217400200
AS-MAustralianAS -133224450125
AS-AAustralianAS -13321740070
SANS-NSouth AfricaSANS-117317400150
SANS-MSouth AfricaSANS-117325450120
SANS-ASouth AfricaSANS-11731840070
IS-N-17IndiaIS 189117400200
IS-M-24IndiaIS 189124450150
JIS-GJapanJIS-K 633214400250
JIS-LJapanJIS-K 633215350200
JIS-DJapanJIS-K 633218400100
JIS-HJapanJIS-K 633224450120
GB-HChinaGB/T 798424450120
GB-DChinaGB/T 798418400100
GB-LChinaGB/T 798415350200
The rubber conveyor belt profile ready for package