Conveyor Belt Tracking Problems: A Comprehensive Analysis of Causes and Prevention Strategies

Introduction: Malfunction Symptoms That Initiate Investigation

Conveyor belt mistracking is one of the most common and costly operational problems in industrial manufacturing. It manifests itself in the form of a displacement of the belt relative to the central axis, which leads to the touching of the conveyor frame, the edges of the belt or the spilling of material. Typical symptoms include:

• Damage to the edges of the tape (friction, tears).
• Uneven wear of tape and rollers.
• Scattering of the transported material on the sides of the conveyor.
• Increased level of noise and vibration.
• Premature failure of components such as bearing assemblies, particularly ABB 3HNP00789-1.

Such malfunctions not only reduce transportation efficiency and product quality, but also pose safety risks to personnel and significantly increase operating costs due to forced shutdowns and repairs. For example, an unplanned stoppage of a 500 t/h conveyor can result in losses of between €5,000 and €15,000 per hour, depending on the industry.

Component Overview: Role of Conveyor and Bearing Assembly ABB 3HNP00789-1

The conveyor belt is a key element in the continuous transportation of bulk and artificial materials. A typical system consists of drive and tension drums (pulleys), roller supports (carrying, reverse, centering), the belt itself, as well as the drive mechanism. Each of these elements plays a critical role in keeping the belt moving in a straight line.

Roller supports hold the belt and transported material, providing minimal movement resistance. Their alignment is fundamental to stability. Drums (driving, tail, deflecting) transmit motion to the belt and ensure its tension. The geometry of the drive and tail drums, in particular the presence of taper (crowning), is crucial for the centering effect of the belt.

Consider the bearing unit ABB 3HNP00789-1. This component is a high-quality housing-integrated spherical roller bearing designed for heavy-duty applications in industrial conveyor systems. It is installed on the shafts of drive or key roller bearings and drums, where it withstands significant radial and axial loads. Its design allows you to compensate for certain angular displacements of the shaft, but only within limited limits. The standard lifetime (MTBF) of such a bearing under ideal operating conditions can reach 80,000 hours. However, under the conditions of constant displacement of the tape and increased dynamic loads, its resource can be reduced to 20,000 - 30,000 hours, which emphasizes the criticality of correct tracking of the tape.

The operating conditions in which the ABB 3HNP00789-1 operates often include:

• Temperature range: from -30°C to +90°C.
• Humidity: up to 95% (with appropriate sealing).
• Dust environment: high concentration of abrasive particles.
• Belt speed: up to 5 m/s.
• Load: up to 15 kN per roller, depending on the configuration.

Compliance with the requirements of the DSTU EN 620:2009 and ISO 5048:2020 standards is mandatory for the safe and efficient operation of conveyor systems.

Evidence of failure: What the technical staff records

Collecting reliable fault data is the first step in determining the root cause. Technical personnel should systematically record visual, acoustic and instrumental indicators:

Visual signs:

• Tip edge wear: Measure the depth and width of the wear. For example, the erosion of the edge of the tape by 5-7 mm in 1000 hours of operation on one side is a clear indicator of constant friction.
• Frame Damage: Scratches, deformations, or holes in the conveyor's metal structures caused by contact with a displaced belt.
• Material shedding: Observed when the belt moves beyond the side shields or when the load is uneven, causing the belt to sag.
• Apparent displacement of rollers/drums: Approximate deviation from a straight line.
• Material build-up: On the surfaces of rollers or drums, which can change their effective diameter.

Acoustic features:

• Squeaking, hissing: Indicates friction of the tape against the structure or uneven sliding.
• Squealing: May indicate damage to bearings, in particular in the ABB 3HNP00789-1 unit, or contact of metal parts.

Instrumental measurements and data:

• Thermography: Using a thermal imager (eg FLIR T-Series) to detect overheated areas. An ABB 3HNP00789-1 bearing assembly surface temperature exceeding 70°C at an ambient temperature of 25°C is a critical "red flag" indicating excessive friction or bearing damage.
• Vibration analysis: Portable vibration analyzers (such as the SKF Microlog Analyzer) allow the identification of specific frequencies associated with misalignment, imbalance, or bearing defects. A deviation of the vibration amplitude of the roller bearing exceeding 4.5 mm/s RMS (corresponding to class B/C according to ISO 10816-3 for non-rigid supports) indicates serious problems.
• Measurement of tape tension: Using a strain gauge, compliance of the tape tension is checked (for example, 1-2% of its ultimate tensile strength, or according to the manufacturer's recommendations). Insufficient or excessive tension can affect tracking stability.
• Laser alignment: Laser alignment systems (eg Pruftechnik SENSALIGN) ensure high accuracy of checking the perpendicularity of the rollers to the axis of the conveyor and the parallelism of the drums. Permissible deviation from perpendicularity for roller supports is usually no more than 1 mm for every 2 meters of roller length.
• Measurement of taper of drums: Measurement of diameters at the edges and in the center of the drum to assess the compliance of the profile with the required taper. Insufficient taper (crowning) or its complete absence is a direct cause of unstable tracking.

These data together form an objective picture of the malfunction, allowing to proceed to a systematic analysis of the root causes.

Root Cause Investigation: A Systematic Analysis

We use a systematic approach to identify the real root causes of conveyor belt misalignment. The "5 why" method or the Ishikawa diagram (fish skeleton) are often used. Let's focus on the key factors:

1. Improper alignment of rollers and drums

• Problem: Tape moves off center.
• Why? Uneven distribution of tension and lateral forces on the tape.
• Why? Rollers or drums are not perpendicular to the axis of the conveyor or parallel to each other.
• Why?
  • Errors during installation: inaccuracy of mounting supports, use of uncalibrated tools.
  • Deformation of the frame: over time under the influence of loads or corrosion.
  • Deterioration of supporting structures: subsidence, backlash.
  • Lack of regular alignment control.

2. Problems with the conicity (crowning) of the drums

• Problem: The tape "runs" off the drum, or is not stabilized in the center.
• Why? Missing or incorrect drive/tail drum crowning geometry.
• Why?
  • Incorrect drum design: calculation error or manufacturing defect.
  • Drum surface wear: especially in the center or at the edges, which changes the effective taper.
  • Material build-up: adhesion of material to the surface of the drum, which creates local irregularities.

3. Uneven load distribution

• Problem: The ribbon moves sideways when loading material.
• Why? The material is fed onto the belt off-center or skewed.
• Why?
  • Incorrect placement of the loading funnel or estrus.
  • Excessive speed of feeding the material, which leads to its "flying" on the belt.
  • Deformation or wear of side restraints.
  • Unbalanced flow of material at the entrance.

4. Improper tape tension

• Problem: Tape slips or oscillates excessively.
• Why? The friction forces between the belt and the drum are insufficient or the tension is uneven.
• Why?
  • Incorrect setting of the tensioner.
  • Tape stretching over time.
  • Wear of the drum lining, which reduces the coefficient of friction.

Identified Root Causes: A Ranked List with Probability and Confirmation

1. Improper alignment of rollers and drums (High probability, >40% of cases):
   • Confirmation: Laser alignment data, visual signs of belt edge wear, increased vibration of roller supports (over 4.5 mm/s RMS at 120 Hz). This reason is often the result of both initial installation errors and gradual deformation of the frame or supports.
2. Uneven distribution of load on the belt (High probability, >30% of cases):
   • Confirmation: Local spillage of material, rapid wear of side shields, displacement of the belt when passing through the loading zone. This problem is often associated with improper positioning of loading devices or uncontrolled material feeding.
3. Drive/tail drum taper issues (Average probability, >15% of cases):
   • Confirmation: Specific belt wear pattern (such as center wear or uneven width wear), drum geometry measurements, and consistent belt misalignment despite proper roller alignment. Build-up of material on the surface of the drum can simulate an irregular taper.
4. Inadequate belt tension (Average probability, >10% of cases):
   • Confirmation: Belt slippage on the drive drum (especially during start-up or peak loads), excessive belt sag between roller supports, belt vibration. Improper tensioning can not only cause misalignment, but also lead to increased wear on drive mechanisms and bearings such as the ABB 3HNP00789-1, reducing their MTBF from 80,000 hours to 30,000 hours.
5. Component wear or damage (Low to medium probability, ~5% cases):
   • Confirmation: Thermographic data (local overheating of bearings >70°C), vibration analysis (frequencies characteristic of bearing or roller defects), visual inspection (roller deformation, wear of bearing assemblies, e.g. ABB 3HNP00789-1). This cause is often a consequence of other root causes that have led to increased loads.

Corrective actions: Immediate correction and long-term prevention

For each identified root cause, a set of corrective actions must be developed, including both immediate measures to restore operability and long-term strategies to prevent repeated failures.

1. Improper alignment of rollers and drums

• Immediate actions:
  • Using a laser alignment system (eg Pruftechnik SENSALIGN) to precisely position all rollers and drums. Check the perpendicularity of the rollers to the axis of the conveyor (tolerance no more than 0.5 mm per meter of roller length) and the parallelism of the drums.
  • Fine adjustments can be made by shifting the roller supports. Apply markings after each adjustment.
• Long-term actions:
  • Develop and implement standard operating procedures (SOPs) for assembly and alignment of conveyor components with mandatory use of calibrated tools.
  • Conduct regular training for technical staff on the use of accurate alignment techniques.
  • Consider installing self-centering roller supports in critical areas.
  • Periodic control of deformation of the conveyor frame and elimination of its causes.

2. Problems with the conicity (crowning) of the drums

• Immediate actions:
  • Clean the surfaces of the drums from adhering material. Make sure there is no mechanical damage or uneven wear that changes the profile.
  • If the conicity is absent or significantly impaired, replace the drum with a new one with the correct profile.
• Long-term actions:
  • Implement regular inspections of the condition of the surface of the drums and control of their geometry.
  • Use a drum lining with a high friction coefficient, resistant to wear and material sticking (for example, a rubber lining with diamond-shaped grooves).
  • Ensure proper cleaning of the belt to prevent material build-up on the drums.

3. Uneven load distribution

• Immediate actions:
  • Adjust the position of the loading hopper or hopper to ensure a centralized and uniform feed of material onto the belt.
  • Reduce feed rate if possible to prevent "flying" and uneven distribution.
• Long-term actions:
  • Optimize the design of loading stations, possibly by installing adjustable guides or using vibrating feeders for even feeding.
  • Implement belt loading control systems (for example, strain gauges under roller supports) to monitor and automatically adjust material feed.

4. Improper tape tension

• Immediate actions:
  • Check the belt tension with a strain gauge and adjust according to the conveyor manufacturer's recommendations. Typically, the tension should provide 1.5% - 2.0% of the ultimate tensile strength of the tape.
  • Check the operation of the tensioning device (screw, cargo, hydraulic).
• Long-term actions:
  • Implement a regular schedule for checking and adjusting belt tension, especially after the new belt has been run-in.
  • Consider installing automatic tension support systems.
  • Choose conveyor belts with minimal elongation under load.

5. Wear or damage to components (for example, ABB bearing unit 3HNP00789-1)

• Immediate action:
  • Immediate replacement of worn or damaged rollers, bearings, particularly ABB 3HNP00789-1, or other structural elements.
  • When replacing the ABB 3HNP00789-1 bearing, make sure to use original spare parts or certified analogues that meet the requirements of EN ISO 15242 and DSTU GOST 520:2014.
• Long-term actions:
  • Implement a Condition Monitoring program for key components using vibration analysis and thermography.
  • Use bearings and rollers designed for maximum operating loads and environmental conditions.
  • Follow the manufacturer's recommendations for bearing lubrication and their replacement intervals.

A quick diagnostic checklist for the field technician

This checklist is designed to quickly assess the condition of the conveyor belt on site and identify warning signs of failure.

1. Visual inspection of the tape: Inspect the edges of the tape for wear, fraying, cuts, or other damage. Is there an offset of the tape relative to the center?
2. Check for material spillage: Is there material accumulation along the conveyor, under rollers or drums?
3. Acoustic monitoring: Listen for unusual noises - creaking, grinding, rumbling. Localize the source.
4. Estimating component temperatures: Gently touch the roller and drum bearing housings (or use a thermal imager). Are some components significantly hotter than others (>70°C ΔT relative to ambient temperature)?
5. Checking the belt tension: Visually assess the slack of the belt between the roller supports. Measure with a strain gauge (if available) and compare with passport data.
6. Inspection of roller bearings: Do all rollers rotate freely? Are there any visible deformations, wear, backlash in the bearing assemblies (eg ABB 3HNP00789-1)?
7. Roller and Drum Alignment: Use a straightedge or laser tool to quickly assess the perpendicularity of the rollers and the parallelism of the drums. Pay attention to the "red flags" - deviations of more than 2 mm per meter of length.
8. Load centralization: Watch the material being fed to the tape. Is it evenly spaced and centered?
9. Drum Liner Condition: Inspect the drive and tail drum liners for wear or damage.
10. Conveyor frame integrity: Inspect support structures for deformation, cracks, or corrosion that may affect geometry.

Prevention strategy: Maintenance intervals, condition monitoring and design improvements

Preventing conveyor belt tracking problems requires an integrated approach that includes regular maintenance, modern monitoring systems and thoughtful design solutions. The main elements of the strategy:

1. Planned preventive maintenance (PPO):
   • Daily/Weekly: Visual inspection of the belt, rollers, drums, loading and unloading areas. Checking the presence of material spills.
   • Monthly: Tape tension check. Cleaning of rollers and drums. Assessment of the condition of the lining.
   • Quarterly: Detailed control of alignment of rollers and drums using laser systems. Vibration analysis of key roller bearings and drive units (eg with ABB bearing 3HNP00789-1). Thermographic control of bearings.
   • Annually: Comprehensive audit of the conveyor system, including checking the integrity of the frame, condition of shafts, supports and replacement of worn components.
2. Condition Monitoring:
   • Installation of stationary vibration control systems at critical roller supports and drive stations for early detection of bearing defects (for example, in the ABB 3HNP00789-1 unit) and misalignment.
   • Use of online thermographic cameras for continuous temperature monitoring of bearing units. A critical increase in temperature of 40°C relative to the norm or exceeding the absolute value of 80°C is a signal for immediate attention.
   • Belt position control systems with automatic adjustment or emergency shutdown.
3. Design improvements:
   • Use of centering roller supports in areas of increased risk of displacement.
   • Modernization of loading stations to ensure a more controlled and centralized supply of material.
   • The use of high-quality conveyor belts, resistant to wear, with minimal elongation and increased strength in accordance with DSTU ISO 340.
   • Installation of drive and tail drums with optimal taper and lining, ensuring stable belt tracking.
   • The use of bearing assemblies that comply with CE and UkrSEPRO certifications, such as ABB 3HNP00789-1, ensures reliability and durability.

Conclusion

Effective conveyor belt tracking is critical to the smooth and safe operation of industrial transportation systems. Ignoring belt misalignment issues not only results in rapid wear of critical components such as the ABB 3HNP00789-1 Bearing Assembly, but also significant financial losses due to equipment downtime and reduced productivity. A systematic approach to diagnosis, identification of root causes and implementation of corrective and preventive measures based on DSTU and ISO standards is the only way to achieve high operational reliability. Investments in precision alignment, quality components and condition monitoring programs pay off in increased equipment life, lower maintenance costs and improved overall production efficiency.

For more information on high-quality components and solutions to optimize the performance of your conveyor systems, visit the UNITEC-D E-Catalog.

Link

• DSTU EN 620:2009. Machines of continuous transport. Security requirements. Belt conveyors (EN 620:2002+A1:2009, IDT).
• ISO 1819:2018. Continuous mechanical handling equipment – ​​Safety and health requirements for the design of belt conveyors for loose bulk materials.
• ISO 5048:2020. Continuous mechanical handling equipment – ​​Belt conveyors with carrying idlers – Calculation of operating power and tensile forces.
• EN ISO 12100:2010. Safety of machinery – General principles for design – Risk assessment and risk reduction.
• DSTU GOST 520:2014. Rolling bearings. General technical conditions.
• EN ISO 15242-1:2015. Rolling bearings – Measuring methods for vibration – Part 1: General guidelines.
• ISO 10816-3:2009. Mechanical vibration – Evaluation of machine vibration by measurements on non-rotating parts – Part 3: Industrial machines with nominal power above 15 kW and nominal speeds between 120 r/min and 15,000 r/min when measured in situ.
• DSTU ISO 340:2004. Textile conveyor belts for mining. Flammability and slip characteristics (ISO 340:2004, IDT).
• ABB manufacturer's recommendations for bearing assemblies of the 3HNP00789-1 series.
• Vibration analysis and thermography manuals from SKF and FLIR Systems.