1、 Mechanical transmission system malfunction

1. Belt slippage or deviation

• Fault phenomenon：
  • Insufficient friction between the belt and the drive drum results in slower or stopped material conveying speed.
  • The belt deviates to one side, causing noise and even jamming due to friction with the frame.
• Root cause analysis：
  • Insufficient belt tension (such as failure of tensioning device, aging of spring).
  • The surface of the drum is worn or stained with oil, which reduces the friction coefficient.
  • The installation of the roller group is tilted or the bearings are damaged, resulting in uneven force on the belt.
  • Uneven distribution of materials (such as excessive stacking on one side) generates lateral forces.
• Solution：
  • Adjust tensionUse tensioning devices (such as spiral or heavy hammer) to increase the pre tensioning force of the belt, ensuring that the tension is within the rated range (usually 5% to 8% of the belt's own weight).
  • Clean the drumUse cleaning agents to remove oil stains, and if necessary, apply rubber coating to the surface of the drum (such as rubber layer thickness ≥ 10mm) to enhance friction.
  • Calibration rollerCheck the levelness of the idler assembly, replace damaged bearings (such as SKF or NSK brand), and ensure that the idler rotates flexibly.
  • Uniform fabricInstall a guide plate or vibrating feeder at the feed inlet to avoid material imbalance.

2. Chain breakage or jamming

• Fault phenomenon：
  • The chain suddenly broke, causing the feeding machine to stop.
  • The chain runs unevenly, producing abnormal noise or vibration.
• Root cause analysis：
  • Improper chain selection (such as bearing capacity lower than actual load).
  • The sprocket is worn or the tooth profile is deformed, resulting in poor meshing.
  • Insufficient lubrication or contamination of lubricating oil can accelerate chain wear.
  • Excessive tension on the chain leads to fatigue fracture.
• Solution：
  • Replace the chainSelect the appropriate model (such as ANSI 40 # or ISO 12B-2) based on load calculation, ensuring a safety factor of ≥ 1.5.
  • Repair the sprocketRepair the worn sprocket by welding or replace it directly (material recommended is 40Cr alloy steel).
  • Regular lubricationAdd high-temperature grease (such as Mobil EP2) every 500 hours and avoid using waste engine oil.
  • Adjust the tension forceUse a spring tensioning device to ensure that the chain sag is within the range of 2% to 3% of the span.

3. Abnormal noise or overheating of the gearbox

• Fault phenomenon：
  • There is a sound of metal friction or impact during the operation of the gearbox.
  • The temperature of the gearbox exceeds 80 ℃ (normally should be ≤ 65 ℃).
• Root cause analysis：
  • Gear wear or pitting can cause excessive meshing clearance.
  • Bearing damage (such as cage rupture, roller peeling).
  • Insufficient oil level or oil deterioration (such as emulsification or impurities).
  • Poor alignment of the coupling results in additional load.
• Solution：
  • replace the gearPerform carburizing and quenching treatment on worn gears (hardness HRC58~62), or directly replace them with new gears.
  • replace the bearingChoose high-precision bearings (such as P5 grade) and control the clearance between 0.03~0.05mm during installation.
  • Oil change and maintenanceReplace industrial gear oil (such as Shell Omala S4 GX 320) every 2000 hours and clean the oil filter.
  • Re centeringAdjust the coupling clearance using a laser centering device to ensure a deviation of ≤ 0.05mm.

2、 Electrical control system malfunction

1. The motor cannot start or trips frequently

• Fault phenomenon：
  • After pressing the start button, the motor has no response or only buzzes.
  • During operation, the motor suddenly stopped and the thermal relay activated.
• Root cause analysis：
  • Power phase loss (such as fuse failure, contactor contact burnout).
  • Motor overload (such as material jamming or transmission component jamming).
  • Control circuit malfunction (such as button damage, relay coil open circuit).
  • Motor insulation damage (such as winding grounding or short circuit).
• Solution：
  • Check the power supplyMeasure the three-phase voltage with a multimeter to ensure balance and within ± 5% of the rated value.
  • Reduce loadClear the blocking material and check if the transmission components are flexible.
  • Repair the control circuitReplace damaged buttons or relays (such as Omron MY2N-J type) and check if the wiring terminals are loose.
  • Test insulationMeasure the insulation resistance of the motor winding to ground with a megohmmeter, which should be ≥ 0.5M Ω (500V range).

2. Inverter alarm or inability to adjust speed

• Fault phenomenon：
  • The frequency converter displays fault codes such as "OC" (overcurrent) and "OV" (overvoltage).
  • The motor speed is unstable or cannot reach the set value during speed regulation.
• Root cause analysis：
  • The acceleration time is too short, resulting in current surge.
  • The braking resistor is damaged and cannot consume regenerative energy.
  • Inverter parameter setting error (such as V/F curve mismatch).
  • The motor cable is too long (>100 meters), causing reflected wave interference.
• Solution：
  • adjust parametersExtend the acceleration time (such as changing from 5 seconds to 10 seconds) and reduce the starting current.
  • Replace the brake resistorChoose a resistor that matches the power (such as a 10kW motor with a 5 Ω/100W resistor).
  • optimize parametersSet the rated voltage, current, speed and other parameters according to the motor nameplate.
  • Install a reactorFor long cable scenarios, install output reactors (such as Schneider ATV630 series matching models) at the output end of the frequency converter.

3. Abnormal sensor signal

• Fault phenomenon：
  • The level sensor falsely reports "full material" or "empty material", causing the feeding machine to malfunction.
  • The speed sensor displays speed fluctuations (such as ± 10% or more).
• Root cause analysis：
  • Improper installation position of the sensor (such as misalignment of the level sensor with the material).
  • The surface of the sensor is contaminated with materials such as dust and oil, which affects the detection accuracy.
  • The shielding layer of the signal line is damaged, introducing electromagnetic interference.
  • The sensor range does not match the actual requirements (such as using a 0-10kPa pressure sensor to measure the 0-50kPa material level).
• Solution：
  • reinstallAdjust the sensor angle (such as installing the level sensor tilted at 15 °) to avoid direct impact of materials.
  • Clean the sensorRegularly blow the surface with compressed air or install a protective cover (such as IP65 rating).
  • Repair the shielding layerRe wrap the damaged signal line with a shielding layer and ground it at one end.
  • Replace the sensorChoose a model with an appropriate range (such as replacing the original 0-10kPa model with a 0-10kPa sensor).

3、 Material conveying system malfunction

1. Inlet blockage

• Fault phenomenon：
  • The material accumulates at the feed inlet and cannot smoothly enter the conveying pipeline.
  • The electric current of the feeding machine suddenly increases, even causing motor stalling.
• Root cause analysis：
  • Excessive humidity of the material (such as moisture content>15%) can cause clumping.
  • The size of the feed inlet is too small (e.g. diameter<2 times the maximum particle size of the material).
  • The frequency of the vibrating feeder is too low, resulting in poor material flow.
• Solution：
  • dry materialDry wet materials (such as using an air flow dryer) and control the moisture content to ≤ 8%.
  • Expand the feed inletAdjust the size of the feeding port according to the particle size of the material (for example, for materials with a particle size of 50mm, the diameter of the feeding port should be ≥ 100mm).
  • Adjust vibration frequencyIncrease the frequency of the vibrating feeder from 30Hz to 50Hz to enhance material fluidity.

2. Leakage at the discharge outlet

• Fault phenomenon：
  • Materials spill from the connection between the discharge port and the pipeline, causing waste and pollution.
  • The wear of the sealing gasket leads to dust leakage.
• Root cause analysis：
  • Loose pipeline connections (such as loose flange bolts).
  • Improper material of sealing gasket (such as replacing silicone rubber with ordinary rubber).
  • Unreasonable design of discharge outlet (such as lack of guide cone, material impact on sealing surface).
• Solution：
  • Tighten the connectionUse a torque wrench to tighten the flange bolts to the standard torque (e.g. 50~60N · m for M12 bolts).
  • Replace the gasketChoose sealing materials that are resistant to high temperatures and corrosion (such as fluororubber O-rings).
  • Optimized DesignInstall a guide cone (cone angle 60 °~90 °) at the discharge outlet to reduce the impact of materials on the sealing surface.

3. Unstable conveying speed

• Fault phenomenon：
  • The material conveying volume fluctuates greatly, affecting the production rhythm.
  • The running speed of the belt or chain fluctuates (such as ± 5% or more).
• Root cause analysis：
  • The output frequency of the frequency converter is unstable (such as being affected by voltage fluctuations in the power grid).
  • Wear of transmission components (such as loose belts and increased chain pitch).
  • Sudden change in material load (such as a sudden increase in feed quantity).
• Solution：
  • stable power supplyInstall a voltage regulator (such as SVC-0.5kVA type) to ensure that the input voltage fluctuation is ≤ ± 3%.
  • Replace transmission componentsReplace the worn belt or chain as a whole and readjust the tension.
  • Buffer loadInstall a buffer compartment (with a capacity of 5-10 minutes of production) at the feed inlet to smooth load changes.