It depends on:

1. Core gum endurance capacity - differs between manufacturers > 100% life cycle endurance strength

2. Splice pattern and loading on core gum rubber and separately on steel cord - 1 step, 2 step, 3 step .... will have a different endurance life for same load

3. Splice pattern can alter loading on rubber and steel cord with better or worse stress risers in each rubber and steel cord

4. Number of loading cycles - belt speed, cycle time of each splice

5. Stress levels in vertical curves, horizontal curves, in belt transitions, on pulley diameter selection, on belt hygienne and build up of contaminates on pulleys

6. Proximity of drive and non-drive pulleys to one-another and on lagging anomalies, on splice anomalies, and on build-up on pulleys.

7. Tracking of belt into high tension zones - 6% traacking error allowance = more than 10% increase in local strength difference from higher stressed side - and in transition design.

8. Number of high tension pulleys belt is wrapped around

9. Steel cord construction

10. Reinforcement fabrics if any

11. Ratio of core gum gap between steel cords and cord diameters in splice - stress stiffening endurance ratings

12. In the final analysis the splice needs to be tested in a full multiple repeat pattern on a endurance test machine such as Goodyear-Veyance or Hannover Univeristy using a fast relaxation period that replicates real world tension drop rate ( i.e. strain-rate drop in rubber). Old DIN or Hannover tests changes strain rate well below practical operations. Need strain rate drop to occur faster than 0.5 seconds such as a 5 m/s belt driving over a 1200 mm drive pulley = (5000 mm/sec belt speed) / (1200 mm dia x PI / 2) = 0.38 seconds from T1 to T2. Big difference to old Hannover (DIN) 2 second (T1 to T2) relaxation time and big difference with rubber's endurance rating.

This was a 20 second test. 60 seconds will yield more input.

Your question is complex and the answer cannot be easily contained in a short synopsis. Ask an expert if you wish a accurate answer. ■

Without the above noted details, no answer is possible.

I left out a major condition, what is the belt's safety factor? Belt Breaking Strength / Belt Operating Tension assuming a constant design load (which is not likely) = 6:1.

A proper design for a belt 1000 m long, with belt speed = 5 m/s = 27,000 peak running cycles per year. A belt can be designed to achieve 10 years life or 270,000 cycles that is verifiable on a splice endurance machine, using a belt safety factor > 5:1, knowing the fatigue rate of the rubber, exclusive of poor design features, and poor starting or stopping regulation. ■

A further condition is the belt life as requested. The belt life will highly depend on the cover selection and more importantly on the chute design. A proper chute design, such as Palabora's hardrock curved spoon, yielded a likely wear life > 20 years for a 1100 m long belt, operating at 4 m/s, loaded on 16 degrees, tranporting -300 mm sharp primary crushed copper ore at 6500 t/h. ■

RCOK 3-D DEM program can prove your chute design and best (maximize) belt life answer. See our website: http://www.conveyor-dynamics.com/rocky.htm ■