What are the differences between the jaw crusher and hammer crusher? How to choose them? In the crushing plant, the jaw crusher must work with a secondary crusher(impact crusher). Then somebody wants to use a hammer crusher replace jaw crusher and impact crusher. Does it feasible? When do we use a jaw crusher, and when do we use a hammer crusher. This article refers to these questions.
1. Working principle
Working principle of the jaw crusher is squeezing the materials. The materials are squeezing crushed in the crushing space which composes of movable jaw and fixed jaw.
But the hammer crusher depends on the impact, cut, laminate of hammer, the materials hit each, and back striking of liner for crushing.
2. Crushed material
Jaw crusher can crush all kinds of hard and soft materials, the compressive strength is between 300-350mpa. Such as granite, quartz, diabase, river pebbles, iron ore, etc.
Hammer crusher crush the materials that hardness is not high. The compressive strength is generally less than 200Mpa. Such as limestone, bluestone, coal gangue, etc. The hammer of hammer crusher wears seriously, It usually takes three days to replace. Therefore, the cost of the parts is high.
Generally speaking, the needle content is relatively high in the materials crushed by the jaw crusher. So the crushing plant usually needs woking with an impact crusher to get a better shape of the finished product.
The hammer crushers are rarely used in the gravel aggregate production line. Although the crushing processing of crusher is simple, the rate of finished products is low, easy to be over crushed, powder materials are too much. And the finished aggregate may produce micro-cracks, low compressive strength which affect the quality of aggregate, the sales and prices. So, it is often used to crush brittle material.
The jaw crushers are used for primary crusher(coarse crushing equipment) in the aggregate plant. It can work with the impact crusher or cone crusher. In the sand plant, it usually works with sand making machine(VSI crusher).
5. Way of adjusting discharge size
How to adjust the hammer crusher’s discharge size? It replaces the bottom screen plate to adjust. There is three ways to adjust the jaw crusher’s discharge size, plate adjustment, wedge block adjustment, hydro cylinder adjustment.
5.1 Plate adjustment
The adjustment plate is generally located behind the adjustment inner elbow plate seat. When it is necessary to adjust the discharge size, the number of the plate can be increased or decreased. Change the total thickness of the plate to change the position of the elbow plate. Move the position of the front and back of the lower jaw to realize the change of the discharge size.
5.2 Wedge block adjustment
The wedge-block adjusting device is mainly composed of two identical wedge- blocks. The wedge block locates behind the inner elbow-plate, and the inclined surfaces of the two wedge blocks are relatively glued together. By changing the relative position of the two wedge blocks, the total thickness of the wedge block pair can be changed. Then change the position of the elbow-plate, move the position of the lower part of the jaw to realize the change of the size of the discharge port.
5.3 Hydrocylinder adjustment
The hydraulic cylinder discharge port adjustment device is equivalent to a large oil cylinder installed in the middle of the elbow plate. So the length of the elbow plate can be changed step-less adjustment, thus changing the position of the front and back of the jaw, realizing the discharge port size adjustment.
The discharge adjustment device of the structure can’t only automatically adjust the size of the discharge opening, but also realize the functions of overload iron and cleaning the cavity. Convenient to operate and reduces labor intensity.
But the production cost of the jaw crusher is high, and the requires of the operation and maintenance skills of workers are higher.