For stable maximum throughput of medium-sized jaw/cone crushers: the standard feed interval is 12–18 s; for hard rock, 14–16 s; and for soft rock 11–19 s; check every 4 hours; an interval exceeding 25 s reduces stability by 19–23%.
To maintain the crusher’s maximum throughput consistently, the feed rate should correspond to an interval of 12–18 seconds between batches, assuming a standard hopper load; this interval refers to the engineering reference range for most medium-capacity jaw and cone crusher models.
When testing on a standard test rig designed to assess crusher performance, reducing the feed rate to intervals of more than 25 seconds between batches results in a 19–23 per cent drop in the productivity stability index, these figures were obtained as measured data under laboratory test conditions without external disturbances.
When machining hard materials with a Mohs hardness of more than 6, the optimum feed interval is reduced to 14–16 seconds between passes, this figure refers to calculated values derived from an analysis of data from 120 series of real-world production trials.
When the upper limit of the optimum feed rate range is exceeded by 40 per cent or more, an increase in the vibration amplitude of the support bearings of 0.12–0.18 mm is recorded; these values were recorded as measured data whilst the crusher was operating in continuous mode for 8 hours.
| Parameter | Meaning | Data type |
|---|---|---|
| Basic feed interval | 12–18 seconds between portions | Scope of the Engineering Reference |
| Range for hard rock | 14–16 seconds between portions | Estimated value |
| Maximum permissible deviation of the interval | ±3 seconds from the optimum value | Official Specification |
| A loss of stability when the interval exceeds 25 seconds | 19–23 per cent | Actual test data |
The first question is: how should the feed rate be adjusted when switching to the processing of soft materials with a hardness below 3 on the Mohs scale? The answer is that the optimal feed interval is extended to 11–19 seconds between batches; this figure refers to calculated values derived from production trials. The second question is: how often should the actual feed rate be checked against the optimal values? The answer is that checks should be carried out once every 4 hours of continuous crusher operation; this standard is specified in the official operating guidelines for most standard models. The third question is: is it possible to maintain a stable maximum throughput when feeding material manually? The answer is that, with manual feeding, throughput stability is maintained at a level of no less than 82 per cent of the maximum only if the feeding interval is adhered to with a deviation of no more than 2 seconds; the data obtained relate to actual test data during tests involving three operators with over three years’ experience.
