Following on with the theme from the Joint Forum meeting held in February this year, a paper was presented by Andrew Jennings of CDI, USA, entitled “On-site Measurement of Conveyor Friction”.
The paper explained that the conveyor friction value is critical on long conveyors with little elevation change. Friction is 50% (low rolling resistance rubber) to 70% (standard rubber) of OPEX. Friction determines belt strength, pulley size and motor size which is a substantial portion of CAPEX.
- Friction determines the acceptable vertical and horizontal curve radii. Width related indentation loss should also be considered. It is possible to compute a conveyor’s drag with relatively crude methods. Relating that drag to the friction factors used in conveyor models is not entirely straightforward. Assumptions need to be made about idler, cleaner, skirtboard, pulley and gearbox losses.
- If the belt is loaded, an accurate weigh scale is required and an evenly loaded conveyor, or the user would need to know how the load is distributed and use software to compute.
- Strain gauges may not be needed to compute but are indispensable tools for recording hidden issues with control systems and components installed on conveyors.
- Not all LRR rubbers are equal, and not all idlers are equal. Rubber losses approximate three to four times idler losses.
This fascinating subject is to be further explored at the next Joint Forum meeting.