Troubleshooting  Large size conveyor chain

General

1Chain is riding up on the sprocket
2The chain winds onto the sprocket (poor separation from the sprocket teeth)
3Unusual noises
4Excessive wear on the inside surface of the chain plates or sides of the sprocket teeth.
5Wear on a sprocket tooth root and tooth pressing surface
6Good articulation
7Chain causes stick-slip (jerking phenomenon).
8Excessive wear on inside of chain plates or on one side of pin of NF block chain or BF chain (no rollers).
9Rusting of the chain
10Excessive wear caused by the conveyed material
11Excessive wear from corrosion
12Electrochemical corrosion

Plate related

13Sudden link plate fracture
14Deformation of plate holes, pin rotation (pin is shifted from normal position)
15Cracks in the plate (1)Fatigue breakage
16Cracks in the plate (2)Stress corrosion crack
17Red pattern found on the plates

Pin related

18(1)Pin fatigue fracture
19(2)Pin corrosive fatigue
20(3)Pin brittle fracture
21(4)Pin sudden fracture

Bush/roller related

22Poor roller rotation, uneven roller wear
23Roller is opening up.
24Roller or bush is split.
25Roller is becoming hourglass-shaped.
Answers

General

1


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Chain is riding up on the sprocket

Cause 1 Chain and sprocket do not match Solution Replace the chain or sprocket with the correct size. Install a tensioner.
Cause 2 Insufficient wrapping angle Solution Wrapping angle must be at least three teeth.
Cause 3 Excessive load Solution Reduce the load (e.g. install a shock absorber).
Cause 4 Insufficient back tension Solution Adjust catenary / take-up, install tensioners.
Cause 5 Excessive chain elongation due to wear. Solution Replace with a new chain.
Cause 6 Distance between the center of chain and sprocket do not match. S≠S’ Solution Inspect and adjust.
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2The chain winds onto the sprocket (poor separation from the sprocket teeth)
Cause 1 Excessive slack in the chain Solution Adjust the chain length or distance between shafts. Or install a tensioner
Cause 2 Excessively worn sprocket, or chain and sprocket do not match. Solution Replace with new chain and sprocket.
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3Unusual noises
Cause 1 Inadequate lubrication to the sliding portions of the pin and bush. Solution Provide adequate lubrication.
Cause 2 Inadequate lubrication to the sliding portions of bush and roller. Solution Provide adequate lubrication. Use a bearing roller or plastic roller.
Cause 3 Winding or riding on the sprocket. Solution See above.
Cause 4 Chain casing or bearings are loose Solution Tighten all bolts and nuts.
Cause 5 Chain or drive area interfering with the casing. Solution Inspect and adjust.
Cause 6 Excessive chain or sprocket wear Solution Replace the chain or sprocket (replace all chains).
Cause 7

Improper setting of the guide rail.


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Solution Inspect and adjust.
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4


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Excessive wear on the inside surface of the chain plates or sides of the sprocket teeth.

Cause 1 Poor centering of sprocket Solution Remove the chain and correct a centering of drive and driven sprockets.
Cause 2 Chain is being pushed to the side. Solution Remove the cause of push. Install a guide roller.
Cause 3 Inclined sprocket caused by poor shaft bore processing accuracy Solution After checking for defective parts, correct and replace with new sprockets.
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5Wear on a sprocket tooth root and tooth pressing surface
Cause 1 Chain wear Solution Replace chain and sprockets at the same time.
Cause 2 Insufficient number of engaged teeth Solution Increase the number of sprocket teeth.
Cause 3 BF chain (no rollers) used Solution Change to RF chain (with rollers).
Cause 4 Insufficient tooth hardness against wear inclusions and excessive loads Solution Use a sprocket with hardened or block replaceable teeth.
Cause 5 Incompatibility between sprocket and chain Solution Replace the chain or sprocket with the correct size.
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6Good articulation
Cause 1 Rusting or corrosion. Solution
  • ・Install a partition to protect the chain.
  • ・Select a suitable chain (e.g. GS Series).
Cause 2 Conveyed material sticks between pins/bushes/plates. Or foreign matter enters. Solution
  • ・Install a partition to protect the chain.
  • ・Select a chain with large clearance between pin, bush and roller.
  • ・Remove particles or contamination, or apply penetrating oil.
Cause 3 Chain deformation due to improper installation Solution Inspect and correct the installation condition of sprocket and shaft.
Cause 4 Insufficient lubrication Solution Consider lubrication or wear-resistant series (CT, BT series, etc.).
Cause 5 Use in extremely high temperatures (over 400°C). Solution Provide adequate clearance.
Cause 6 Seizing from excessive loads. Solution Reduce load. Lubricate regularly (e.g. install a lubricator).
Cause 7 Pin bending due to excessively high loading. Solution Reduce load. Lubricate regularly (e.g. install a lubricator).
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7Chain causes stick-slip (jerking phenomenon).
Cause 1 Change the rolling friction coefficient of chain. Solution
  • ・Clean and lubricate moving parts with Tsubaki oil.
    (・Contact a Tsubaki representative. )
  • ・Replace with new sprockets.
  • ・Switch to Bearing Roller Conveyor Chain.
Cause 2 Conveyor speed is too slow. Solution Increase conveyor speed.
Cause 3 Insufficient rigidity in the frame. The conveyor chain is small compared to the device. Solution
  • ・Increase the frame rigidity, increase the chain model number.
  • ・Decrease the slack in the drive chain.
Cause 4 The force of friction is excessively large. Solution
  • ・Lubricates between guide rail and chain to reduce frictional forces.
  • ・Switch to Bearing Roller Conveyor Chain.
Cause 5 Conveyor length is too long. Solution Shorten the conveyor length by dividing the conveyor.
Cause 6 Speed variation due to polygonal action Solution Number of drive sprocket teeth shall be 12T or more.
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8Excessive wear on inside of chain plates or on one side of pin of NF block chain or BF chain (no rollers).
Cause 1 Increased internal tension when engaging the sprocket. Solution
  • ・Attach supporting blocks to the sprocket.
  • ・Reduce load.
    Lubricate both chain and sprocket.


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9Rusting of the chain
Cause 1 Inappropriate selection of material. Solution Select a more suitable chain material. Protect the chain from the environment. Apply a rust inhibitor (lubrication, cover).
Cause 2 Condensation Solution Eliminate the temperature difference between the inside and outside of the conveyor (e.g. using insulation). Install a drain to remove water.
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10


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Excessive wear caused by the conveyed material

Cause 1 Conveyed materials that are particularly abrasive, such as ore powder, stick to the chain, causing the chain surface is being worn away. Solution
  • ・Prevent conveyed material from falling onto the chain.
  • ・Use a wear-resistant chain.

    →Please consult us.

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11


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Excessive wear from corrosion

Cause 1 Corrosion due to exposure to acid and alkaline fluids, combined with mechanical wear, and accelerates abrasion. Solution
  • ・Use a chemical-resistant material.
  • ・Use wear-resistant materials for parts where mechanical wear occurs.

    →Please consult us.

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12


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Electrochemical corrosion

Cause 1 When the chain is covered with water or passes through a solution, the sliding parts of the chain form local batteries and the surface is subject to galvanic corrosion. Solution
  • ・Use a chemical-resistant material.
  • ・Use wear-resistant materials for parts where mechanical wear occurs.

    →Please consult us.

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Plate related

13Sudden link plate fracture
Cause 1 Excessive load, too much tension on take-up. Solution
  • ・Eliminate the cause of overloading.
  • ・Install a safety device (e.g. a Tsubaki Shock Relay).
  • ・Increase chain size. (size up).
Cause 2 Reduction in strength due to wear and corrosion Solution
  • ・Replace with a new part. Install a cover to protect the chain.
  • ・Lubricate regularly.
  • ・Select a chain with the proper specs for the application.
Cause 3

Plates are pressed outward by sprocket teeth.


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Solution
  • ・Check and correct the installation accuracy.
  • ・Check for excessively worn chain or sprocket, and replace as necessary.
  • ・Check if the chain and sprocket match, and correct as necessary.
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14Deformation of plate holes, pin rotation (pin is shifted from normal position)
Cause 1 Overload Solution
  • ・Eliminate the cause of overloading.
  • ・Increase chain size. (size up).
Cause 2 Improper installation of the connecting link. Solution Replace connecting link with a new one.
Cause 3 Excessive load and inadequate lubrication. Solution Replace with a new chain and improve the lubrication and loading conditions.
Cause 4 Sticking between pin and bush, poor articulation. Solution
  • ・Increase chain size. (size up).
  • ・Use a chain with a larger clearance between pin and bush.
  • ・Lubricate between pin and bush with penetrating oil.
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15


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Cracks in the plate (1)Fatigue breakage

Cause 1 Excessive load, or excessive take-up tension. Excessively large repetitive load. Solution Eliminate overloading or large repetitive loads.
Cause 2 Load greater than maximum allowable load is acting. Solution
  • ・Increase chain size. (size up). or specs of the chain to raise maximum allowable load.
  • ・Replace with new chain or sprocket
Cause 3 A repetitive load is acting on the attachments. Solution
  • ・Eliminate overloading or large repetitive loads.
  • ・Increase the chain size to increase the allowable load of the attachment.
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16


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Cracks in the plate (2)Stress corrosion crack

Cause 1 The chain is being used in an acidic or alkaline environment.
Not affected by repetitive load.
Solution
  • ・Install a cover to protect the chain from the environment. Replace with new chain or sprocket
  • ・Use a chain with a high resistance to stress corrosion cracks.
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17Red pattern found on the plates
Cause 1 Scale adhering to the plate material Solution
  • ・Can continue to be used as is (DT, DTA, AT, etc.).
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Pin related

18


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(1)Pin fatigue fracture

Cause 1

If a load exceeding the maximum allowable load is applied repeatedly, the pin may be fatigue fractured.

The peak load acts like a repetitive load on the chain.

Solution
  • ・Check the size of the peak load and eliminate its cause.
  • ・Replace the chain with a larger size (larger pin diameter).
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19(2)Pin corrosive fatigue
Cause 1

A tensile load is applied to the side with pit, and the fracture progresses from the point of pit.

This is particularly likely to occur if the surface of the pin is corroded, making it weak to bending.

Solution
  • ・Install a cover on the chain. (See Plate related > Cracks in the plate > (2) Stress corrosion crack)
  • ・Use a pin made of an anti-corrosion material (e.g. MT).
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20(3)Pin brittle fracture
Cause 1

Poor environment.

Solution
  • ・Switch to anti-corrosive pins.
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21(4)Pin sudden fracture
Cause 1

Overload

Solution
  • ・Increase chain size. (size up).
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Roller, Bush related

22Poor roller rotation, uneven roller wear
Cause 1

Roller load is excessive.

Solution Provide sufficient lubrication between the bushes and rollers. Consider bearing roller or DTA Series.
Cause 2

Conveyed material/foreign objects enter between bush and roller.

Solution Clean regularly, and install a partition to protect the chain.
Cause 3

Conveyed material/foreign objects accumulate on the rails.

Solution Clean regularly and install a partition to minimize accumulation.
Cause 4

Lubricant adheres to the roller surface and rail without entering between bushes and rollers and between rollers and plates.

Solution Select an appropriate lubricant and lubrication method.
Cause 5

Roller/bush rust.

Solution Select an appropriate specification (e.g. RT).
Cause 6

Inner plate is moving sidewards.

Solution Replace with a new chain. Re-inspect the installation and load conditions.
Cause 7

Bush is cracked.

Solution Reduce the load and lower the speed of rotation.
Cause 8

Contact between side of roller and side of plates due to thrust load

Solution Eliminate the cause of thrust load.
Cause 9

The chain and sprocket do not match, or excessively worn teeth.

Solution Check the tooth profile.
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23Roller is opening up.
Cause 1

Excessive load, too much tension on take-up.

Solution Reduce the load, provide adequate lubrication, and remove any large steps in the rail. Loosen take-up.
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24Roller or bush is split.
Cause 1

Excessive load, too much tension on take-up.

Solution Reduce the load and provide adequate lubrication. Loosen take-up.
Cause 2

Too few teeth with respect to conveyor speed.

Solution Increase the number of teeth. Decrease the speed.
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25Roller is becoming hourglass-shaped.
Cause 1

Excessive load or improper lubrication

Solution improve the lubrication and loading conditions, and replace the chain with a new one.
Cause 2

Excessively worn rail.

Solution Correct or replace the rail.
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