A steel cord Conveyor Belt is a high-tensile conveyor belt that uses longitudinally arranged steel cables as its tension member — embedded in a rubber compound — instead of the multiple textile plies found in fabric conveyor belts. This construction delivers tensile strengths up to 4,000 N/mm, ultra-low elongation (0.1%–0.25%), and exceptional impact resistance — making it the primary choice for long distance belt conveyors spanning 5 km to over 15 km in a single flight. This article explains steel cord belt construction, specifications (ST630–ST4000), cover grade options, and how to select the right steel cord rubber conveyor belt for mining, cement, and port applications.

Steel Cord Conveyor Belt Construction

The construction of a steel cord conveyor belt centers on a single layer of evenly spaced, longitudinally arranged steel cables. Each cable is manufactured from high-carbon steel wires twisted into a 7×7 or 7×19 configuration, depending on the tensile strength grade required. The cables are galvanized to prevent corrosion and bonded to the surrounding rubber through a specialized adhesion compound.

Key construction layers:

• Top cover rubber: The carrying side — thickness from 5 to 12 mm depending on material abrasiveness and impact. Available in abrasion-resistant (DIN Y/Z), heat-resistant (T1/T2/T3), flame-retardant (ISO 340), and oil-resistant grades.
• Steel cord layer: Zinc-coated steel cables at 10–25 mm pitch, with diameters from 2.5 to 12.2 mm depending on strength grade. The cord pitch determines the belt's troughability and impact resistance.
• Core rubber (bonding layer): A high-adhesion rubber compound that fills the spaces between cables, bonding the top and bottom covers while preventing cable corrosion and fretting.
• Bottom cover rubber: The pulley side — typically thinner than the top cover (3–6 mm), engineered to grip drive pulleys and resist wear from conveyor rollers.

Steel Cord Belt Specifications: ST630–ST4000

Steel cord belts are designated by the ST prefix followed by the nominal tensile strength in N/mm. The table below shows standard specifications available from ZOOMRY.

Grade	Tensile Strength (N/mm)	Cord Diameter (mm)	Cord Pitch (mm)	Typical Application
ST630	630	2.5 – 3.0	10 – 12	Short overland, mobile stackers
ST1000	1,000	3.0 – 4.0	12 – 14	Medium overland, plant conveyors
ST1600	1,600	4.0 – 5.0	12 – 16	Long overland, high-lift conveyors
ST2000	2,000	5.0 – 6.0	14 – 18	Long distance, high tonnage
ST2500	2,500	6.0 – 7.2	15 – 20	Overland, steep incline, high-tension
ST3150	3,150	7.2 – 8.5	17 – 22	Extra-long overland, 10+ km systems
ST4000	4,000	9.0 – 12.2	20 – 25	Maximum tension, 15+ km single flight

Belt widths available from 800 to 2,400 mm. Top cover thickness 5–12 mm, bottom cover 3–6 mm. Custom cover grades per application requirements.

Cover Grade Options for Steel Cord Rubber Conveyor Belt

The rubber cover compound is selected based on the material being conveyed and the operating environment. ZOOMRY steel cord rubber conveyor belts are available in the following cover grades:

Cover Grade	Standard	Max Temp	Best For
Abrasion-Resistant	DIN Y / DIN Z	80°C	Iron ore, copper, aggregates, bauxite
Heat-Resistant	T1 / T2 / T3	100–200°C	Cement clinker, sinter, hot casting
Flame-Retardant	ISO 340 / EN 12882	80°C	Underground coal, explosive environments
Oil-Resistant	DIN 22102	70°C	Woodchips, biomass, chemical plants

When to Choose a Steel Cord Conveyor Belt

Select a steel cord rubber conveyor belt when your application meets one or more of the following conditions:

• Conveyor length exceeds 1,000 meters: Low elongation (0.1%–0.25%) minimizes take-up stroke — a critical advantage in long distance curved belt conveyors where take-up travel impacts tunnel or gallery design cost
• High tension requirement: When calculated belt tension exceeds 1,600 N/mm — common in iron ore and copper overland conveyors with high lift and tonnage
• Long service life expected: Steel cord belts in cement and power plant applications routinely achieve 15–20 year service life
• High impact loading: When primary crushed material (lump size 300 mm+) drops directly onto the belt, steel cords resist gouging better than fabric plies
• Multi-flight systems: Fewer splices across 15+ km systems mean fewer failure points and lower inspection costs

Frequently Asked Questions

Q: What is the difference between steel cord and fabric conveyor belts?

Steel cord belts use a single layer of steel cables for tensile strength (up to 4,000 N/mm) with ultra-low elongation (0.1%–0.25%). Fabric belts use multiple plies of woven textile (EP or nylon) with tensile strength up to 3,150 N/mm and higher elongation (1.5%–4%). For a detailed comparison, see our guide: Steel Cord vs Fabric Conveyor Belt: Which One Do You Need?

Q: How are steel cord belts spliced?

Steel cord belts require hot vulcanized finger splicing — the steel cables are exposed, interleaved in a finger pattern, and bonded under heat and pressure with fresh rubber compound. A properly executed splice can last the full service life of the belt. Splice time is typically 6–12 hours for a skilled crew, compared to 2–4 hours for fabric belt mechanical fasteners. The longer splice time is offset by the fact that steel cord belts need far fewer splices over their lifespan.

Q: What is the minimum pulley diameter for steel cord belts?

Minimum pulley diameter increases with cord diameter and tensile strength. For ST630–ST1000 belts, minimum drive pulley diameter is typically 600–800 mm. For ST3150–ST4000 belts, this increases to 1,250–1,600 mm. This is significantly larger than fabric belt requirements (minimum ~250 mm), making steel cord belts unsuitable for applications with small pulleys — such as mobile stackers and compact conveyors.

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