Standard Reference: ISO 6972 (Specification for welded crank link mill chains, attachments and sprockets). Major domestic manufacturers including Huangshan Hengjiu and Donghua produce chains complying with this ISO standard. Chains and sprockets of the same model from different manufacturers are interchangeable.

1. Core Structural Characteristics & Key Differences From Standard Roller Chains

WH welded crank link mill chains are heavy-duty welded engineered chains without rollers, distinct from stamped and assembled roller chains.

1. The chain plate is formed by bending a solid steel plate followed by welding, adopting an integrated bent-plate welded construction. This structure delivers far higher rigidity than ordinary stamped chain plates made by high-speed stamping processes.
2. Pins and bushings serve as the primary load-bearing components, with no separate rollers. This design effectively prevents jamming caused by dust, mud and fine debris, which is its core advantage for operating environments such as mines, wood chip yards and mineral chutes.
3. Pre-drilled side mounting holes for SA/FA attachments are integrated on the chain links. Scraper flights, buckets and push plates can be directly fastened onto the chain with bolts, eliminating extra welding work for fitting attachments.
4. The crank link bent-plate structure features built-in flexibility. It can withstand frequent impacts, repeated start-stop cycles and offset loads. Conventional roller chains are prone to link fracture and jumping teeth under heavy shock loading.

Two main configurations are available: Narrow WH and Wide WDH. The narrow series features compact inner width and low center of gravity, suitable for medium-load scraper conveying tasks. The wide series comes with widened chain plates for enhanced tensile strength, designed for high-volume material flow, large scraper assemblies and heavy-duty dredging conveyor applications.

2. Material Selection & Heat Treatment (Critical Points for Foreign Trade Negotiations)

The mainstream standard material is 40Cr or 42CrMo alloy structural steel.

• Chain pins: Carburizing quenching treatment. The surface achieves excellent wear resistance while the core retains sufficient toughness to avoid brittle fracture of pins under dynamic load.
• Crank link plates: Quenched and tempered plus shot blasting treatment to improve fatigue resistance. The rounded corners of bent sections are high-stress concentration zones; the quality of corner radius processing directly determines the overall service life of the chain.
• Bushings: Carburizing quenching for outstanding wear resistance and extrusion resistance.

Optional upgrade versions: Stainless steel grades 304 and 316L for humid and corrosive working conditions, such as sugar mills and wet processing workshops.

Common industry pitfalls: Small workshops adopt ordinary Q235 or 45# steel without carburizing treatment. Products from these suppliers suffer from rapid pin elongation and weld cracking after short service time, and their minimum breaking load data is often falsely marked. Overseas buyers place heavy emphasis on formal minimum breaking load certification documents.

3. Main Application Industries (Customer Development Directions)

1. Wood processing industry (the most mature application): Wood chip conveyors, flaker conveyors, slab conveyors and shavings conveyors. Huangshan WH chains hold a dominant market share in this field.
2. Sugar manufacturing industry: Sugarcane conveyors and cane residue scraper conveyors.
3. Mining & aggregates industry: Ore, gangue and crushed stone scraper conveying systems.
4. Power plant ash handling: Boiler bottom ash removal under high-temperature and abrasive working conditions.
5. Agricultural harvesting: Combine harvesters and straw conveying equipment.
6. Building materials industry: Pulverized coal and clinker bulk material conveying.

✅ Unified working condition summary: Low speed, heavy load, high dust concentration and impact loading. These chains are NOT suitable for high-speed transmission. The recommended linear speed is generally ≤0.6 m/s; standard roller chains are the preferred option for high-speed conveying scenarios.