During long-term operation, screw conveyor components such as screw flights, bearings, drive assemblies, and conveying troughs are exposed to mechanical loads, material abrasion, and environmental conditions. Regular inspection of fasteners, lubrication, screw flight wear, and equipment sealing helps prevent blockages, abnormal vibration, bearing damage, and drive overload.
Maintenance requirements depend on the conveyor design. A shafted screw conveyor requires particular attention to the screw shaft, shaft connections, and intermediate hanger bearings. A shaftless screw conveyor requires closer inspection of the shaftless spiral flight, drive connection, and wear-resistant trough liner. The maintenance procedures for these two designs are not identical.
Routine Screw Conveyor Maintenance
Inspect Fasteners and Drive Connections
During operation, the motor, gearbox, screw shaft, and flight connections are continuously subjected to rotational loads and vibration. Regularly inspect the equipment connections to prevent loose bolts, deformed connectors, or component displacement.
Pay particular attention to the following areas:
Screw shaft connections: Inspect the connecting bolts between the screw shaft, shaft couplings, and individual screw sections. Check for looseness, missing fasteners, and visible wear.
Drive assembly: Check the mounting bolts of the motor, gearbox, and base. Inspect the coupling and other transmission connections for abnormal conditions.
Bearing housings: Check the connections between bearing housings and the equipment frame. Confirm that there is no looseness or displacement.
Trough connections: Inspect trough sections, flanges, inspection covers, and seals to prevent material leakage or dust release caused by loose connections.
If loose screw shaft connection bolts are found, stop the equipment and isolate the relevant energy sources before tightening them. If bolts are broken, connection holes are worn, or shaft ends are deformed, investigate the cause of the abnormal loading before carrying out repairs or replacements. Simply retightening the bolts may not resolve the underlying problem.
Check Bearings, Hanger Bearings, and Lubrication
Bearings support the screw shaft and other rotating components. Their condition directly affects the rotational resistance and transmission stability of the conveyor.
Check for abnormal noise, temperature rise, vibration, excessive clearance, or restricted rotation. Also inspect the condition of the grease or lubricating oil.
For shafted screw conveyors with intermediate hanger bearings, pay particular attention to their mounting positions, wear, and lubrication. Hanger bearings are generally installed between adjacent screw sections. Their alignment affects the operating condition of the screw shaft. A displaced or severely worn hanger bearing can cause changes in shaft deflection, increased running resistance, and abnormal vibration.
Shaftless screw conveyors do not have the central shaft and intermediate hanger bearings found in conventional shafted designs. However, the drive-end supports, bearings, and sealing components still require inspection.
Follow the bearing and equipment manufacturer's specifications for lubrication intervals, lubricant type, and grease quantity. Insufficient lubrication increases friction and wear. Excessive lubrication or the use of an unsuitable lubricant can also cause temperature and sealing problems.
Inspect Screw Flights and Trough Wear
The screw flights come into direct contact with the conveyed material and are the main working components of the conveyor. When transporting abrasive materials such as sand, gravel, mineral powders, and granules, the flight surfaces may wear over time. Sticky materials can also accumulate on the flights and trough.
Inspect the following components:
Flight surfaces: Check for excessive material loss, cracks, local deformation, and damage around the connections.
Screw shaft and connecting sections: Inspect the shaft for bending and check the connecting sections for looseness or wear.
Trough walls: Look for wear-through, deformation, corrosion, and material buildup.
Wear liners: On equipment fitted with liners, check their wear condition, mounting bolts, and clearances. Replace them when necessary.
For shafted screw conveyors, also check the operating clearance between the flight edges and the trough. This helps prevent abnormal contact during rotation. For shaftless screw conveyors, pay particular attention to the contact and wear condition between the spiral flight and the wear liner.
If abnormal friction, metal-to-metal contact, or increased screw resistance occurs, stop the equipment and inspect for foreign objects, deformation, or installation misalignment.
Inspect the Drive Unit and Transmission System
The drive unit supplies the rotational power required by the screw shaft or shaftless spiral flight. Its operating condition affects the conveying capacity of the equipment.
Routine inspection should cover the following:
Electric motor: Check operating current, temperature, and noise. Look for abnormal vibration or frequent overload trips.
Gearbox: Inspect lubricant level, oil condition, seals, and operating noise. Investigate oil leakage or abnormal temperature rise.
Coupling: Check connecting bolts, flexible elements, and alignment to prevent additional loads caused by installation errors.
Drive chains or belts: If the equipment uses a chain or belt drive, inspect wear, tension, and tracking.
If motor current remains high or the equipment generates an overload alarm, check whether the feed rate is excessive, the trough is blocked, or the screw flights and bearings are experiencing mechanical binding.
Inspect Seals and Material Residue
Screw conveyors generally use an enclosed trough or tubular casing. The end bearings, drive end, and inspection covers require suitable sealing arrangements.
Inspect shaft seals, end-cover seals, and trough connections for material leakage, oil leakage, or dust release. Replace seals that have deteriorated, deformed, or become damaged.
When conveying sticky, high-moisture, or hardening materials, residues may accumulate on the screw flights and inside the trough. Over time, this buildup can interfere with screw rotation.
Before cleaning, stop the upstream feeding equipment and allow the conveyor to discharge as much material as possible according to the operating procedure. Then stop the machine and isolate all relevant energy sources. Materials that are corrosive, moisture-sensitive, or prone to hardening may require timely removal to prevent deposits from affecting subsequent operation.
Installation and Trial-Run Adjustments
After initial installation, disassembly and maintenance, or replacement of screw sections, inspect the mounting positions and clearances of the main components. Incorrect clearances or assembly misalignment can cause abnormal friction, vibration, and component wear.
Hanger Bearing Position and Clearance
In a shafted screw conveyor, hanger bearings are generally installed between adjacent screw sections. They must be positioned according to the design requirements and correctly aligned with the screw shaft.
During installation, check the following:
Whether the hanger bearing is positioned within the specified central area between adjacent screw sections.
Whether sufficient operating and assembly clearance is provided between the hanger bearing, connecting shaft, and screw pipe ends.
Whether the hanger bearing is correctly aligned with the screw shaft.
Whether the bearing fasteners and support frame are securely mounted.
A displaced hanger bearing or insufficient clearance may create additional friction between the screw shaft and bearing components, potentially causing abnormal axial loading.
The exact mounting distance and allowable clearance should be determined from the equipment assembly drawings and manufacturer's technical documentation. Different screw diameters, connection arrangements, and hanger bearing designs have different requirements. A single set of dimensions should not be applied as a universal standard.
Clearance Between Screw Flights and the Trough
The screw flights require an appropriate operating clearance from the inner surface of the trough. This prevents abnormal friction during operation while allowing material to move through the conveying section.
After installation or maintenance, check whether the clearance remains reasonably uniform along the conveyor. Pay particular attention to the drive end, tail end, and areas around intermediate hanger bearings.
For shafted designs, inspect the clearance between the outer edges of the flights and the trough. For shaftless designs, check the fit between the spiral flight and wear liner according to the equipment design.
Insufficient clearance may cause the flights to rub against the trough or liner. Excessive clearance can reduce conveying efficiency and increase material residue.
Also inspect the joints between trough sections. Deformation, misaligned connections, or uneven support may cause local changes in clearance.
Inspect the Screw Shaft and Section Connections
Sectional screw conveyors generally use connecting shafts, shaft couplings, or other connecting structures to join individual screw sections.
During assembly, check the connections between screw sections, the fasteners, and the relative flight positions. Confirm that adjacent sections can transmit torque according to the equipment design.
For designs with hanger bearings, make sure that each bearing is correctly positioned between the adjacent screw sections and does not interfere with the flights.
After assembly, manually rotate the screw using the method specified by the manufacturer. Check for smooth movement and look for binding, excessive runout, or metal-to-metal contact.
No-Load Test Run
After mechanical assembly and electrical inspection, carry out a no-load test according to the equipment instructions.
During operation, check the following:
Whether the screw flights rotate in the specified direction and run smoothly.
Whether the motor and gearbox produce abnormal noise, vibration, or temperature rise.
Whether the bearings and hanger bearings show signs of binding, unusual noise, or excessive heating.
Whether the coupling and screw section connection bolts remain secure.
Whether shaft seals and other sealing points show oil or grease leakage.
Whether abnormal friction occurs between the trough, screw flights, and wear liners.
If oil or grease leakage occurs around a bearing seal, first inspect the sealing components, mounting condition, and bearing lubrication. Adjust or replace the sealing arrangement when necessary. Do not remove bearings or adjust internal seal components while the equipment is running.
Once the no-load test is satisfactory, gradually introduce material according to the equipment requirements. Monitor motor current, conveying capacity, and discharge condition during the loaded test.
Safety Precautions During Screw Conveyor Maintenance
Stop the Equipment and Isolate Energy Before Maintenance
Before checking fasteners, removing inspection covers, adjusting bearings, or cleaning material from the trough, stop the equipment and disconnect the power supply to the motor and associated auxiliary equipment.
For conveying systems that may restart through remote control, automatic control, or interlocking with other equipment, apply lockout/tagout procedures or equivalent energy isolation measures. This prevents unexpected startup during maintenance.
Pressing the stop button alone does not establish a safe maintenance condition.
Never Remove Guards While the Equipment Is Running
Never remove inspection covers, end covers, guards, or other protective structures while the screw conveyor is operating.
The screw shaft, flights, and couplings are rotating components. Contact with these parts can cause entanglement or crushing injuries. Do not place hands, tools, or other objects inside the feed inlet or inspection openings. Internal material must not be removed while the equipment is running.
Internal inspection and maintenance should only begin after the equipment has been fully stopped, all relevant energy sources have been isolated, and residual mechanical hazards have been addressed.
Select the Conveyor According to Material Properties
Screw conveyors are not suitable for every type of bulk material. Materials with strong adhesion, high moisture content, or a tendency to agglomerate may stick to the flights and accumulate inside the trough, causing the screw to bind.
For materials containing long fibers, strips, or other components that tend to wrap around rotating parts, the difference between shafted and shaftless designs should also be considered.
Conventional shafted conveyors may experience material entanglement around the center shaft and hanger bearings. Shaftless designs reduce this risk but require attention to wear between the spiral flight and the trough liner.
Select the screw configuration, rotational speed, and equipment structure according to particle size, moisture content, adhesion, bulk density, and abrasiveness.
Control the Feed Rate to Prevent Overloading
The conveying capacity of a screw conveyor depends on the screw diameter, pitch, rotational speed, material fill ratio, and material properties.
If the upstream feeding rate exceeds the equipment's design capacity, material may accumulate inside the trough. This increases motor current and screw resistance and may lead to drive overload or mechanical damage.
The upstream feeding equipment should therefore be matched to the conveying capacity of the screw conveyor. If frequent overloads occur, investigate the actual feed rate and material condition rather than simply increasing motor power or changing protection settings.
Recommended Screw Conveyor Maintenance Schedule
Maintenance intervals should be determined according to operating hours, material abrasiveness, moisture content, working environment, and manufacturer requirements. The following schedule provides a general inspection reference. Actual intervals should be adjusted to suit operating conditions.
| Maintenance stage | Main inspection items |
|---|---|
| Each shift or daily | Check fasteners, operating noise, motor temperature, bearing condition, sealing, and external material buildup. |
| Periodic inspection | Inspect screw flight wear, trough and wear liners, hanger bearings, couplings, and transmission components. |
| Planned maintenance | Check screw shaft straightness, shaft connections, bearing clearance, sealing arrangements, and drive system condition. |
| Shutdown maintenance or extended storage | Remove residual material from the trough, inspect wear components, and carry out lubrication, rust prevention, and storage procedures according to the manufacturer's instructions. |
Lubricant replenishment and replacement intervals should follow the requirements of the gearbox, bearing, and lubricant manufacturers. A universal quarterly oil replacement schedule should not be applied to every screw conveyor.
For equipment operating continuously, handling highly abrasive materials, or working in dusty environments, inspection frequency may need to be increased.
Custom Machining for Screw Conveyor Components
Screw conveyors contain various precision mechanical and non-standard metal components, including screw shafts, shaft-end connectors, bearing housings, hanger bearing brackets, drive mounting bases, connecting flanges, wear liner mounting parts, and support structures.
The dimensional accuracy, concentricity, hole positions, thread quality, and assembly fits of these components affect screw shaft operation, bearing alignment, and long-term equipment stability.
Hansheng Automation provides CNC precision machining of non-standard metal components according to customer-supplied engineering drawings. These services support structural and transmission components used in screw conveyors and other industrial conveying equipment.
In addition to conveying equipment components, we also undertake custom machining of precision yacht parts, RC racing car parts, tobacco packaging machinery components, and filling machinery parts.
