Jaw Crusher Opening Size
The size of the opening into the crushing chamber. Two numbers, such as 24X36, commonly describe this. Where the opening between the top of the front and rear jaw plates is 24”, and the width between the side cheek plates would be 36”. The width number is directly related to the production capacity, while both numbers will provide guidance for what the maximum size of rock that can be fed to the crusher. Typically you would not want to feed the crusher rock that is larger than 90% of the maximum opening.
Jaw Crusher Nip Angle
The nip angle describes the angle the stationary jaw plate and the pitman make with each other. The exact value of this angle isn’t quoted or even determinable due to curvature in the jaws themselves but what is important is how wide vs. narrow it is. Wide nip angles can tend to expel material as the jaw closes as a large ball might squirt out from under a car tire. If the nip angle is narrow, not much vertical upward force is generated and more consistent crushing takes place.
Jaw Crusher Discharge Opening Size
The discharge opening is the major factor for determining production capacity. The width will remain the same, but opening and closing the discharge setting will affect both the maximum discharge stone as well as the tonnage capacity. The larger the opening the greater the capacity. The discharge setting will be determined by the maximum size rock you want to discharge from the crusher. The maximum size you want discharged will be determined by what the discharged material will be used for. If you want to directly use the discharged material as a final product, then the discharge setting will need to be smaller than the maximum size of the final product. If the discharged material will go on to a secondary crusher, then the discharge setting will need to be set a little smaller than the maximum size rock that can be fed to the secondary crusher.
It is important to remove all materials that are already sized to the target final product prior to feeding the material to be crushed into the crusher. This will increase the productive capacity of your crushing operation, and reduce the cost per ton for wear items.