1. Explore conveyor belt grades: how to choose the right type of belt
Conveyor belts are at the heart of industrial conveyor systems, and the concept of “conveyor belt grade” actually refers to the grade of cover rubber on the top and bottom of the belt. Each grade of cover rubber corresponds to a different rubber standard, which determines the suitability and performance of the conveyor belt in a specific working environment. For the sake of convenience, this article refers to them as conveyor belt grades. Choosing the right grade of cover rubber can not only effectively protect productivity and equipment safety, but also improve the energy efficiency of the conveyor system and extend the service life of the equipment.
1.1 What is conveyor belt grade?
Conveyor belt grades are quantitative grading systems for material properties and usage scenarios based on international standards (e.g. ISO 283, DIN 22102). The system covers three core dimensions:
- Mechanical properties:These include tensile strength (in N/mm), elongation, and interlaminar bond strength;
- Chemical properties:temperature resistance range, oil/acid/alkali corrosion resistance, aging resistance, etc;
- Functional certification:specialized certification for specific scenarios such as flame retardant, anti-static and food grade.
For example, “ST2500” in the ISO 283 standard represents that the longitudinal tensile strength of conveyor belts is 2500N/mm, while “EP600” indicates that each layer of polyester canvas can withstand a tensile force of 600N/mm. This grading method provides a unified technical language for the global industry chain.
1.2 Importance of choosing the right grade
Choosing the right grade of conveyor belt is critical to equipment life, energy efficiency and safety. Incorrect grade selection can lead to equipment damage or production standstill. Specifically:
- Over-selection:Using too high a grade can result in wasted material and increase purchasing costs by more than 30%;
- Under-selection:Low-grade conveyor belts are prone to breakage under heavy loads or extreme conditions, causing production stoppages;
- Compliance risk:conveyor belts that do not pass MSHA (mine safety certification) or FDA (food contact certification) may trigger legal disputes.
Scientific selection can reduce the overall operating costs of a conveyor system by 18%-25%, while extending service life by 40%-60%. Therefore, the correct selection of the right grade is the key to ensure efficient and stable operation of conveyor belts.
1.3 Overview of different grades and their industry significance
According to application scenarios, conveyor belts can be divided into five basic grades, which are suitable for different industry needs:
- General-purpose:suitable for normal temperature, light load material transfer, such as electronic product assembly line;
- Heavy-duty type:for ore and steel transportation in mining and steel industries;
- High temperature resistant type:resistant to high temperature environment of 100℃-400℃, commonly used in metallurgy and cement industries;
- Corrosion-resistant:resisting the erosion of oil, acid and alkali chemicals, mostly used in chemical plants, automobile manufacturing;
- Safety protection type:with flame retardant, anti-static and other functions, dedicated to coal mines, dust explosion risk areas.
The classification of these grades enables the selection of suitable conveyor belts according to different application requirements, so as to realize the best working efficiency and production safety.
2 Understanding Conveyor Belt Classes
2.1 Definition and Classification
The classification of conveyor belt grades is mainly based on the following three major technical standard systems:
Mechanical performance standards:
- ISO 283 (International Organization for Standardization):defines tensile strength classes (ST/EP series);
- DIN 22102 (German Industrial Standard):defines the strength and modulus of elasticity of the canvas layer.
Material chemistry standards:
- ASTM D378 (American Society for Testing and Materials): determines the oil resistance of rubber;
- ISO 340 (international standard): evaluation of flame retardant properties.
Application Scenario Standards:
- FDA 21 CFR 177.2600 (food grade approval);
- EN 14973 (EU flame retardant certification).
2.2 Methods of determining conveyor belt grades
Conveyor belt grades are usually determined by laboratory tests and scenario simulations for scientific grading. The tests include:
- Mechanical test:Use tensile testing machine to measure the breaking strength and constant load elongation;
- Environmental simulation:testing for performance degradation at -60°C to 400°C in a temperature-controlled chamber;
- Chemical analysis:testing the resistance of the rubber molecular structure to oils/acids and alkalis by spectrometer;
- Lifetime prediction:extrapolation of material aging cycles based on the Arrhenius equation.
Through these precise tests, a suitable grade can be selected for the conveyor belt to ensure that it can perform optimally in practical applications.
2.3 Factors affecting grade selection
When choosing the right grade of conveyor belt, the following key parameters need to be considered:
- Load strength:the weight of materials transferred per hour, particle size and impact force;
- Operating environment:temperature fluctuation range, humidity, dust concentration, risk of chemical exposure, etc;
- Equipment parameters:mechanical conditions such as conveyor length, inclination angle, roller diameter, etc;
- Regulatory requirements:industry mandatory certification standards, e.g., coal mine conveyor belts must be MSHA certified.
These factors will directly affect the selection of conveyor belt grade, only according to the actual situation of reasonable selection, in order to ensure the high efficiency and safety of the conveyor belt.
3. Common Conveyor Belt Classes
3.1 General Purpose Grade
General purpose grade conveyor belts are suitable for light load and normal temperature material transportation, and are widely used in many standard working environments.
- Material composition:natural rubber (NR) cover + polyester canvas (EP) reinforcement;
- Performance range:Tensile strength EP100-EP1000, applicable temperature -20℃~80℃;
- Typical applications:light parcel sorting, primary processing of agricultural products, warehousing and logistics systems.
3.2 Heavy-duty grade
Heavy-duty grade conveyor belts are designed to withstand high-intensity working environments, especially suitable for mining, steel and other high-load industries. Its reinforced structure and special materials can withstand large impact forces and high loads.
- Reinforcement structure:Steel cable core (ST) or steel wire rope arranged longitudinally;
- Strength grading:ST1000-ST6300, which can withstand the impact load of ore and steel;
- Technical advantage: 50% less tensile deformation rate than traditional canvas belt.
3.3 High temperature grade
High-temperature grade conveyor belt adopts heat-resistant material, which can keep long-term stable operation under high-temperature environment. Commonly used in metallurgy, cement and other high temperature process places.
- Heat-resistant materials:silicone rubber, EPDM rubber (EPDM) or ceramic coated composite materials;
- Temperature threshold:150℃-200℃ (cement clinker transfer).
3.4 Oil-resistant grade
Oil-resistant grade conveyor belts have good oil resistance through chemical modification treatment and are suitable for chemical and automobile industries, especially for materials that need to be transported with oil and chemicals.
- Chemical modification:Nitrile rubber (NBR), Fluorine rubber (FKM);
- Performance index:Volume expansion rate <10% under ASTM D471 standard (24 hours immersion);
- Applicable scenes: automobile engine parts transportation, oil processing plant.
3.5 Flame-retardant and fire-retardant grade
Flame retardant and fire resistant grade conveyor belts are designed specifically to provide protection in high fire risk environments with flame retardant, anti-static and tear resistant features.
- Safety mechanisms:
- Flame retardant layer:smoke suppressant such as aluminum hydroxide is added;
- Conductive layer: surface resistance <3×10^8Ω;
- Tear-resistant layer:cross-woven with aramid fibers;
- Certification standards: MSHA (U.S. mine safety), EN 14973 (EU flame retardant certification).
- Safety mechanisms:
4. Special grade conveyor belts
In industrial applications, general-purpose conveyor belts are often unable to meet the demands of specialized environments. For this reason, special grade conveyor belts have been developed, combining material science and functional design to provide precise solutions for high-risk areas. Depending on the requirements of different industries, special grade conveyor belts can provide enhanced performance in a number of areas, especially in food processing, chemical industry, mining and other fields.
4.1 Food Grade Conveyor Belts
Food grade conveyor belts are mainly used in the food processing and pharmaceutical industries to ensure compliance with strict hygiene and safety standards, to avoid contamination and to meet food safety regulations. These conveyor belts are made of FDA-approved materials and aseptic design, which can effectively inhibit the growth of pathogens and ensure food safety.
Material Safety Standards:
- Cover layer: FDA 21 CFR 177.2600 certified white PVC or silicone rubber with heavy metal migration below 0.01mg/dm² to ensure compliance with food grade safety standards;
- Reinforcement layer:polyester canvas must be ISO 22000 food safety management system certified to prevent microbial growth and ensure hygiene and safety.
Hygienic design features:
- Seamless surface process:avoiding material residue through seamless design, dramatically improving cleaning efficiency by more than 60%;
- Antimicrobial additives:Antimicrobial additives are used to effectively inhibit the reproduction of common pathogens such as E. coli and Salmonella, ensuring the safety of food during processing.
Application Scenario:
- Food processing: baking production line, meat sorting and conveying;
- Pharmaceutical industry:tablet packaging line, medical equipment sterilization transmission.
4.2 Anti-static conveyor belt
Anti-static conveyor belts are designed for high-risk environments such as explosions and fires caused by static electricity buildup, and are suitable for hazardous environments such as coal mines and chemical dust. This kind of conveyor belt effectively avoids static electricity accumulation and prevents sparks or explosions through special conductive properties.
Conductive performance parameters:
- Surface resistance: 10^4~10^6Ω (in accordance with EN 61340-5-1), which ensures that the conveyor belt has good electrical conductivity during operation;
- Volume resistance:≤10^8Ω-cm (to prevent explosion caused by static buildup), ensuring safety through stable conductivity.
Material composite technology:
- Carbon black dispersion layer:uniformly doped with conductive carbon black particles, resistivity fluctuation rate <5%, to ensure stable conductivity performance;
- Copper wire conductive mesh: 1mm diameter tinned copper wire, longitudinally embedded in the conveyor belt, spacing ≤ 20mm, effectively enhancing the conductivity.
Hazardous environment adaptation:
- Coal mine underground:through MSHA certification, to ensure that the surface ignition energy>0.24mJ, can be safely operated in mines and other high-risk environments;
- Chemical dust area:electrostatic discharge rate <10mJ/s, inhibit dust deflagration.
4.3 Wear-resistant grade conveyor belt
Wear-resistant grade conveyor belts are specially designed for high abrasion environments and can cope with high impact and high abrasion working conditions such as mines and gravel. This type of conveyor belt ensures stable performance for a long time in extreme environments by reinforcing the abrasion and impact resistance of the material.
Material Reinforcement Program:
- Cover rubber:High purity Nitrile Rubber (NBR) is used, combined with Aluminum Oxide ceramic particles, with an abrasion resistance index of ≥150mm³, adapting to the harsh working environment;
- Reinforcement layer: using aramid fiber and steel cable composite structure, impact resistance increased by 300%.
Wear protection mechanism:
- Groove design:The design of U-type or V-type grooves helps to reduce material sliding friction and prolong the service life of the conveyor belt;
- Edge Reinforcement: Double-layer polyurethane wrapped edge design extends the life of resistance to lateral abrasion by 2 times and enhances durability.
Typical application scenarios:
- Mining crushing line:for conveying iron ore, granite and other hard materials;
- Sand and gravel aggregate yard:for high abrasion operation over 300 tons per hour.
5. How to choose the right grade of conveyor belt
Scientific selection requires the establishment of a three-dimensional “performance-cost-risk” evaluation model. Below is a systematic decision path to help you make the right selection decision in different industries.
5.1 Core Selection Considerations
Load intensity:
- Static load: Calculate the maximum single point load (unit: kg/m);
- Dynamic Impact: Evaluate the height of material fall and particle size distribution. For example, ores over 50mm require ST grade steel cable belts.
Environmental resistance:
- Temperature range: Consider instantaneous peak temperature (e.g. hot billet conveying in steel mills) versus continuous operating temperature to select the appropriate high temperature resistance class;
- Chemical corrosion:select the grade of corrosion resistance based on the pH value of the material, the polarity of the oil, etc.. For example, polar oils require FKM rubber to provide oil resistance.
Durability indicators:
- Life expectancy:For heavy-duty environments, a life expectancy of >18 months is recommended, and for light-duty environments >36 months;
- Maintenance Costs: In high wear environments, refurbishable belt designs are preferred to reduce long term maintenance and replacement costs.
5.2 Recommendations for selection by industry
The following are the recommended conveyor belt grades and technical basis for different industries:
| Application | Recommendation Level | Technical Basis |
| Food Processing | FDA Certificates PVC Conveyor Belt | Avoid food contamination, HACCP audited |
| Mining | ST1600+Abrasion Resistant Conveyor Belt | Impact strength ≥15k/m² |
| Port Logistics | Flame Resistant EP Belt + Conductive layer | Conforms to ISMCode Maritime Safety Code |
| Automobile Manufacturing | NBR Oil Resistant Conveyor Belt | Resistant to ASTM#3 oil swelling <8% |
| Cement Production | EPDM Heat Resistant Conveyor Belt | Long-term resistance to 200°C clinker radiant heat |
6. Conveyor Belt Grade Standards and Certification
A global standardization system provides the basis for quality control of conveyor belts. The following is an explanation of the key framework to ensure that all conveyor belts meet industry requirements.
6.1 International Standard System
Mechanical Performance Standards:
- ISO 283: defines tensile strength ratings (EP/ST series) and fatigue test methods to ensure that conveyor belts can be operated under load for long periods of time;
- DIN 22102:defines the qualification threshold of ≥6N/mm for the adhesive strength of canvas layers to ensure the strong structure of the conveyor belt.
Functional safety standards:
- EN 14973:EU smoke toxicity limit for flame retardant conveyor belts (CO concentration <1450ppm) for high risk environments;
- AS 1333: Australian test protocol for surface resistance of antistatic belts, ensuring safe use in static-sensitive areas.
6.2 Compliance Certification Process
- Factory Audit: Including raw material traceability, production process and testing equipment calibration to ensure that the products comply with international quality standards;
- Sample testing:
- Type testing:full performance testing is carried out, usually taking 4-6 weeks;
- Batch sampling:3 meter samples are taken every 5000 meters for destructive testing.
- Certificate maintenance:annual supervision and audit to ensure that the quality system continues to be effective and that the products comply with the latest standards.
6.3 Quality and Safety Guarantee
Raw material control:
- Natural rubber:adopt Malaysia SMR20 standard rubber, ash <0.8%;
- Polyester canvas:breaking strength ≥600N/mm, moisture content <2%.
Process monitoring:
- Vulcanization process:temperature deviation is controlled at ±2℃, time precision ±15 seconds to ensure uniform vulcanization;
- Lamination precision:canvas alignment error ≤1mm/10m, ensure consistent structure of each conveyor belt.
Terminal inspection:
- Non-destructive flaw detection:use X-ray equipment to detect defects in steel cable alignment with a resolution of 0.1mm;
- Simulation test: 2000 times of cycle test in the temperature box from -40℃ to 150℃ to ensure the conveyor belt can still run stably under extreme temperature.
