Engineer's Guide

Inspection / Maintenance

Lifespan of Chains and Sprockets


1) Link Plate Wear

Degree and severity of wear is unevenly distributed to different sections of the plate. Wear depends on the type of goods being transported as friction can occur in 3 main places: between the case and the transported goods, inside the links, and at the sides of rollers. Contact is differentiated, therefore uneven distribution of wear can occur.

2) Inner-Wear of Pins and Bush

A winding movement is generated between chain and sprocket wheel at which time the pin and bush’s inner surface undergo wear. Over a long period of use, the pitch is elongated, resulting in the overall elongation of the chain.

3) Wear of the Rollers

Although wear to the outer diameter is significant, when compared to other parts it does not affect the performance. When using R of F roller, depending on wear of the contact side and/or bush contact point, rollers can be used until the bottom of the link plate comes into contact with the rail.


If you start to reach the limit of the link plate at the rail, it not only promotes pin and bush wear but also increases frictional resistance and may cause increased tension, which can lead to a lack of output to the driving chain.


The usage limit of S rollers depends on the accurate assembly of the sprocket which results in smooth mesh points. S rollers can be used until the point where holes begin to appear.

4) Pitch Elongation

Friction that occurs at the curved parts of the rail and at the chain-sprocket mesh point causes wear to the pins and bushes which, over time, results in the overall elongation of the pitch.


Chain elongation limits about 2-3% of the original chain dimensions.


As illustrated in the diagram below, the chain elongation amount is calculated by measuring the state of applied tension of more than 4 links of chain.

5) Sprocket Wear

When sprocket teeth are worn (as shown in the diagram to the left), the meshing between chain and sprocket is not smooth, thus causing damaging vibration.


In the case of this type of grinding wear, overlay welding (for reinforcement) or reverse assembly of sprockets is possible.


Wear of the sprocket wheel’s tooth root is proportional to the chain speed. Operating limit vary slightly depending on the type of conveyor and chain size. Modification or replacement usually takes place when the wheel is worn 3-6 mm.


Reference: Overlay welding rods should be selected from among the DF2B-B standard

Metal with a hardness of HV350 ~ HV600 should be selected based on the amount of wear observed.

In addition, use compound D4316 for basic welding when there is extensive damage.





Tension Adjustment of Chain

When there isn’t enough tension the chain becomes slack, which results in unsmooth conveyance.

In particular, when the slack is extreme, the chain will coil around the sprocket, interrupt with the rail, and can cause a large malfunction. Therefore, careful periodic adjustment of the chain tension is essential.


Inspection Frequency (Operational Standard of 8 hr/day)
Within one week of commencing operation Once Monthly

Because it is typical in cases of continuous operation, please increase the number of inspection times when applied to situations of repeated loads and high corrosion, such as in adverse environments.

Within one week of commencing operation Once Weekly
After 1 Month Twice Monthly
Chain Tension Adjustment

Please smoothly remove the chain from the sprocket.


Please leave enough space at the frame and/or rail to avoid interference of the apron, chain, etc.


Please adjust so as to avoid surging.

Horizontal Flow Conveyor δ = 1/10L ~ 1/20L
  • When operation is repeatedly interrupted
  • When chain speed is high (25m/min)
  • When chain is large or heavy
  • When transferring materials of extreme heat
δ = 1/15L~ 1/25L




Sprocket Mounting


  • Flow Conveyor : Within ±1.0mm/1m
  • Bucket Conveyor : Within ±0.5mm/1m
  • Long Fan Conveyor : Within ±0.5mm/1m
  • Slat Conveyor : Within ±0.5mm/1m
The parallelism should be adjusted by ± 1mm
  • Adjust so that the driving and driven sprockets are on the same plane.
  • Flow Conveyor: Within δ=1mm
  • Bucket Elevator: Within δ=2mm
  • Long Fan Conveyor: Within δ=1mm
  • Slat Conveyor: Within δ=1mm
One-sided Sprocket Wheel-Tilting Phenomenon (failure)
 

- Acceptable Accuracy -

Under 10 m of length ± 8mm

Over 10 m of length ±10 mm





Lubrication

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TEL : +82-31-984-4435 / FAX : +82-31-984-4452 / E-mail : rf430@unitel.co.kr

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