There are a number of different criteria to consider when selecting the right chamber for your crushing needs. There is one, however, that must always be considered. That you have well-graded feed to the chamber. A well-graded feed is generally thought to be 90-100% passing the closed- side feed opening, 40-60% passing the midpoint and 0-10% passing the closed-side setting.
A feed that is not well graded will invariably cause one or more problems with the crushing operation. If the feed is too coarse or too fine, the following problems could develop.
1.Reduced TPH through the crusher.
2.Feed too coarse = low horsepower consumption, too fine = high horsepower consumption
3.Coarse feed will not produce as cubical a product as it should be.
4.Feed too coarse will cause the upper part of the crushing chamber to wear out
5.Feed too fine can cause upper frame movement
6.Oil temperature will rise if feed is too fine
7.Most importantly is the difference in capacity from a new liner to a worn out liner as the reduction in capacity is caused by the lower portion wearing faster than the upper portion which causes the feed operation to close off.
Choke Feeding Is A Proven Aid
In order to maintain the maximum levels of capacity, gradation and cubical product, a crusher must be choke fed at all times. The best way to keep a choke feed to the crusher is with a surge bin ( or hopper) and feeder that are located prior to the crusher. Choke feeding is almost impossible to achieve without a hopper and feeder.
When the crusher feed is reduced, the product tends to become coarse, with slivers and flats occuring.
When should you replace a liner in your crusher?
If the liner is wearing evenly throughout the chamber, you should consider changing out the manganese when it has worn down to about 25mm thick at the bottom. At about 19mm to 16mm thick, the manganese will crack, causing the backing material to begin to disintegrate. This in turn will cause the liners to break loose. If this happens, continued operation could destroy the seat on the support bowl or the head of the crusher.