Chain conveyors and stacker cranes are common material handling systems in industrial automation. However, their structural designs and operating loads differ, so their material requirements are not the same.
For chain conveyors, material selection covers the frame, conveyor chain, sprockets, and support components. The main considerations are conveying load, chain wear, operating speed, and the working environment.
For stacker cranes, the mast, frame, load carriage, travel wheels, forks, and transmission components must provide sufficient strength, stiffness, and wear resistance during horizontal travel, vertical lifting, and load handling.
Material selection should be based on the machine structure, load, operating environment, and required service life rather than the equipment name alone.
Common materials used in chain conveyors
A chain conveyor generally consists of a frame, conveyor chain, sprockets, drive assembly, support legs, and guide components. These parts perform different functions and therefore require different materials.
Frame materials
The frame supports the conveyor chain, drive unit, guide rails, and conveyed loads. It must provide sufficient strength and stiffness to prevent excessive deformation during operation.
Common materials include:
Carbon steel: A common choice for general industrial conveyor frames. It offers good structural strength and machinability and is suitable for ordinary dry indoor environments. Paint, powder coating, or other corrosion protection is normally applied to reduce rust.
Stainless steel: Commonly used in food processing, beverage production, pharmaceutical facilities, and humid environments. Type 304 stainless steel is suitable for many general washdown and food equipment applications. Type 316 may be considered where chlorides, salts, or more aggressive cleaning agents are present.
Aluminum alloy: Used mainly in light-duty, modular, or frequently reconfigured conveyor systems. Its low weight and ease of assembly are useful, but structural stiffness and load capacity must be checked against the actual profile and connection design.
Conveyor frames may use cold-formed channels, rectangular steel tubes, rolled sections, or aluminum extrusions. These are structural forms rather than material categories.
Conveyor chain materials
The conveyor chain is the main load-bearing and power transmission component of a chain conveyor. It generally consists of link plates, pins, bushes, rollers, and connecting parts. Different components require materials selected according to their loads and wear conditions.
Common materials include:
Carbon steel: Suitable for general industrial conveying conditions. It offers good strength and cost efficiency and is widely used for chain plates and other structural chain components.
Alloy steel: Used for chain components subject to high tension, impact loads, or demanding fatigue conditions. Appropriate heat treatment can be selected according to the component design.
Stainless steel: Suitable for humid, frequently washed, or mildly corrosive environments. Different stainless steel grades have different levels of corrosion resistance, hardness, and wear performance.
Engineering plastics: Some slat chains, modular chains, and light-duty conveyor chains use POM, polypropylene, or other engineering plastics. These materials offer low weight, favorable friction characteristics, and corrosion resistance, but their load capacity and temperature limits must be checked against product specifications.
Different parts of a chain do not necessarily use the same material. For example, the link plates may be made from carbon steel, while pins and bushes receive surface hardening treatment. Rollers may use hardened materials to meet wear requirements.
Chain selection should therefore consider the materials and heat treatment of the pins, bushes, and rollers rather than only whether the chain is made from carbon steel or stainless steel.
Sprocket and transmission materials
Sprockets engage with the conveyor chain and transfer drive power. Their materials must provide sufficient strength and resistance to tooth wear.
Carbon steel and alloy steel are common choices. For chain conveyors subject to high loads or frequent starting and stopping, heat treatment such as quenching or other surface hardening processes may be selected according to tooth contact stress and wear requirements.
Drive shafts, connecting shafts, and other transmission components also need to match the required load and torque. Sprocket tooth geometry, tooth count, chain pitch, and material hardness must be compatible to prevent abnormal wear caused by poor engagement or unsuitable hardness combinations.
Support legs and auxiliary structures
Support legs carry the conveyor frame and transfer its load to the floor.
Common configurations include fixed-height supports and adjustable-height supports. Fixed supports are used when the installation height is defined and does not require frequent adjustment. Adjustable supports can accommodate floor level differences or installation height requirements.
Support legs may be made from carbon steel sections, stainless steel tubes, or aluminum profiles, depending on the equipment load, installation environment, and corrosion protection requirements.
Fixed-height and adjustable-height describe support configurations. Carbon steel, stainless steel, and aluminum are material categories.
Common materials used in stacker cranes
A stacker crane performs horizontal travel, vertical lifting, and load handling. Its structure must support the weight of the load and withstand dynamic forces, vibration, and localized impact during operation.
Frame and mast materials
The frame and mast form the main load-bearing structure of a stacker crane. They are commonly manufactured from structural steel sections, steel plates, and welded box structures.
Common material options include:
Structural steel: Offers good strength, stiffness, and weldability. It is commonly used for masts, upper and lower beams, and the base frame.
Alloy structural steel: Used for shafts, connecting components, or other highly stressed parts where strength, fatigue resistance, and toughness requirements justify its use.
Aluminum alloy: Some light-duty and compact stacker cranes use aluminum extrusions for the mast to reduce machine weight and integrate guide features. Suitability depends on load, machine height, and stiffness requirements.
For example, some Mecalux miniload stacker crane models use extruded aluminum mast profiles in light-load configurations, while other load capacities use internally reinforced structural steel box masts. This shows that there is no single mast material for all stacker cranes. The choice depends on machine design and rated capacity.
Load carriage and fork materials
The load carriage supports the goods and fork mechanism. It is commonly made from steel plates and structural sections with welded construction to provide sufficient strength and stiffness.
Forks must withstand bending stress, torsional loads, and contact wear during extension and retraction. Steel with suitable strength is commonly used. Tempering or other heat treatment may be applied according to the load and design requirements.
For double-deep or multi-section telescopic forks, the guide clearances, structural stiffness, and movement coordination between sections also need to be controlled.
Travel wheels and guide components
Travel and guide wheels affect the smooth movement, guidance accuracy, and service life of a stacker crane.
Common materials include:
Steel: Used for wheel cores, axles, and structural components subject to significant loads.
Polyurethane: Used as a tread or coating on some drive and travel wheels. It provides elastic contact and friction characteristics and can reduce direct metal-to-metal contact.
Engineering plastics: Nylon, POM, and UHMW-PE may be used for guide rollers, sliding guide blocks, and wear strips, depending on contact pressure, temperature, and wear conditions.
Bearing steel: Used in rolling bearings and other precision rotating components, selected according to load, speed, and lubrication requirements.
Not all stacker crane travel wheels use polyurethane coatings. The actual material depends on the wheel-to-rail arrangement, load, and operating conditions.
Hoisting and transmission components
The hoisting and transmission systems of a stacker crane may include wire ropes, chains, drums, gearboxes, gears, shafts, and couplings.
These components require materials selected according to tensile force, torque, bending stress, and wear requirements.
For example, gears and transmission shafts may use suitable alloy steels with tempering, carburizing, or other heat treatment according to tooth contact and fatigue requirements. Wire ropes and lifting chains must meet the machine's rated load and safety requirements.
Protective and auxiliary materials
Electrical covers, cable protection components, buffers, and some vibration isolation structures may use plastics, rubber, or polyurethane.
Typical applications include:
Rubber or polyurethane buffers that absorb part of the impact during equipment contact or stopping.
Engineering plastic guide components that reduce sliding friction and metal wear.
Plastic protective covers for selected electrical and mechanical components.
Elastic sealing materials that reduce the entry of dust, moisture, and other contaminants.
These materials are generally used for auxiliary or non-primary load-bearing components. They cannot replace the metal structures required for critical load-bearing parts such as masts, base frames, and forks.
Material selection for special operating environments
When equipment operates in humid, corrosive, high-temperature, low-temperature, or high-wear environments, material selection must also account for chemical resistance, heat treatment, lubrication, and surface protection.
Humid and corrosive environments
Stainless steel frames, chains, and connecting components may be considered for humid warehouses, food processing areas, and frequently washed production zones.
Type 304 stainless steel is suitable for many general corrosion conditions. Where higher concentrations of chlorides, salts, or aggressive cleaning agents are present, Type 316 or another corrosion-resistant material may be more appropriate, depending on the specific exposure.
Stainless steel does not provide the same corrosion and wear performance across all grades. Austenitic and martensitic stainless steels differ in hardness, heat treatment capability, and corrosion resistance.
High-wear and heavy-load conditions
For conveyor chain pins, bushes, rollers, sprocket teeth, and stacker crane gears, suitable alloy steels and surface treatments can be selected according to contact stress and operating conditions.
Common processes include:
Carburizing and quenching: Increases the carbon content at the surface of suitable steels. Quenching then produces a harder surface layer to improve wear resistance.
Surface hardening: Produces a hard outer layer while retaining toughness in the core.
Quenching and tempering: Improves the overall balance of strength, toughness, and fatigue performance.
For example, chain pins and bushes may receive carburizing and quenching treatment to reduce wear at the articulating joints.
Carburizing and surface hardening are mainly used to improve surface hardness and wear resistance. They do not directly improve the inherent high-temperature or low-temperature capability of the material.
High- and low-temperature environments
For high-temperature applications, consider changes in material strength, loss of hardness, oxidation, and lubricant degradation during continuous operation. Chains, bearings, and lubricants must be selected for the actual operating temperature.
For low-temperature applications, check low-temperature impact toughness, lubricant flow properties, seal performance, and the possibility of condensation and ice formation.
For rigid chain drives or other special transmission arrangements, confirm that the chain plates, pins, connecting components, and lubrication system are suitable for the required temperature range. Surface coatings may improve corrosion protection under specific conditions, but they do not replace the need to select a base material with suitable temperature properties.
How to select materials for chain conveyors and stacker cranes
Material selection should not be based only on comparing the price of steel, aluminum alloy, and stainless steel. The actual equipment structure and operating conditions must be considered.
Select materials according to load and stress
Define the maximum load, operating load, dynamic impact, and duty cycle. For frames and masts, check strength, stiffness, and structural stability. For chains, gears, and pins, consider tensile force, fatigue, and contact wear.
Select materials according to the working environment
Carbon steel with suitable corrosion protection may be used in dry industrial environments. Humid and washdown areas require consideration of stainless steel and sealing arrangements. More corrosive environments require a material grade selected according to the actual chemical exposure.
Consider wear and maintenance requirements
Components subject to frequent meshing, rolling, or sliding contact require suitable hardness, surface treatment, lubrication, and clearances. A compatible material combination helps reduce abnormal wear and extend service life.
Match materials to the equipment structure
Different chain conveyors use different chain designs, while stacker cranes may use different hoisting and travel arrangements. Material selection must match the actual structure, component dimensions, and manufacturing process. A material solution developed for one machine should not be applied to all equipment without evaluation.
In summary, chain conveyor material selection must account for frame load capacity, chain strength, pin and roller wear, and environmental conditions. Stacker crane materials must provide suitable strength, stiffness, and fatigue performance in the mast, load carriage, forks, and transmission components. Selecting materials according to the working conditions of each component helps balance operating reliability, maintenance cost, and service life.
In addition to precision mechanical components for conveyor and automated warehousing equipment, Hansheng Automation provides custom precision machining services for other industrial applications, including tobacco packaging machinery, food filling equipment, yacht components, and remote-controlled racing cars. We manufacture non-standard precision components according to customer-supplied drawings and support individual parts and small-batch production.
