What Is A Jaw Crusher

Jaw Crusher Overview

Jaw crusher is a primary crushing equipment that crushes large materials by compression force, and is often called “rock crusher” because of its powerful crushing capacity. In fields such as mining, quarrying and recycling, it undertakes the critical task of crushing hard and large materials into smaller particles, providing the basis for subsequent secondary crushing or processing.

Key advantages

• Material adaptability: capable of handling a wide range of materials from hard granite to recycled asphalt pavement (RAP) with less wear and tear than primary impact crushers.
• Low dust and fines output:During the crushing process, less fines and dust are typically generated, which contributes to a better working environment and reduced subsequent processing costs.
• High efficiency and energy saving:Compared with primary gyratory crushers, it has higher crushing efficiency in specific scenarios and can complete primary crushing of materials more quickly.
• Compact design adapts to narrow space:due to its small size, the jaw crusher is perfect for underground mining, mobile crushing and other space-constrained scenarios, which is difficult to achieve with some other primary crushing equipment.

Different Types of Jaw Crushers

Single Elbow Jaw Crusher

The Single Elbow Plate Jaw Crusher is a relatively simple structure utilizing a single movable jaw plate that swings back and forth. This design allows it to perform well with non-abrasive materials (e.g. limestone) and is often used where the crushing force is not particularly high.

Double Elbow Jaw Crusher

The Double Elbow Plate Jaw Crusher has two jaws involved in the movement, one fixed and one movable, and this design gives it a stronger crushing force. As a result, it is more suitable for handling harder materials (e.g. granite, basalt) and is able to cope with tougher crushing tasks.

Mobile Jaw Crusher

The Mobile Jaw Crusher is mounted on tracks or wheels and is highly mobile. This makes it ideal for construction sites, small crushing operations and other scenarios that require frequent movement, allowing it to flexibly carry out crushing work at different locations.

Laboratory Jaw Crusher

The Laboratory Jaw Crusher is a small crushing plant, mainly used in scientific research and testing environments. It is capable of accurately crushing small quantities of material to facilitate scientific research and material analysis.

Components of a Jaw Crusher

• Frame:As the structural skeleton of the machine, it is usually made of high-quality steel to provide strength and stability for the equipment and ensure the reliable crushing process.

• Jaws:Including fixed jaws and movable jaws, the fixed jaws remain stationary while the movable jaws move back and forth to realize the crushing of materials. The jaws are usually toothed to improve crushing efficiency.

• Crushing Chamber:Located between the two jaws, this is the area where the material is crushed. Its V-shape design makes the material enter from the wide upper part, gradually be squeezed and crushed, and then discharged from the narrow lower part. The design of the crushing cavity (including the gap between the jaw plates) directly affects the crushing efficiency.

• Flywheel: a heavy wheel for storing energy so that the jaw plates can move smoothly and continuously to ensure the stability of the crushing process.

• Elbow plate:helps to keep the jaw plate in the correct position during operation and absorbs the impact load to protect the equipment from sudden impact damage.

• Eccentric shaft: Converts the rotational energy of the motor into the reciprocating motion of the movable jaw plate, which is the key component to transfer the motion.

How do jaw crushers work?

The working process of the jaw crusher is as follows: the material enters through the wide upper opening of the crushing chamber, and the movable jaw plate reciprocates relative to the fixed jaw plate, generating mechanical pressure and crushing the material. With the movement of the movable jaw plate, the material is squeezed in the crushing cavity, and gradually moves from the wide area at the upper part to the narrow area at the lower part, and is finally crushed into smaller particles and discharged from the lower part.

The movable jaw plate of Single Elbow Plate Jaw Crusher makes elliptical movement, while Double Elbow Plate Jaw Crusher utilizes oscillating movement to crush hard materials. The crushing force is generated by the eccentric shaft and transmitted to the crushing area through the elbow plate system. Spring tension rods provide a non-rigid connection throughout the system, and centrifugal mass on the eccentric shaft is used to compensate for heavy loads.

Due to the angle between the two jaws, the material enters the crushing chamber at a significantly reduced size. The final size distribution of the crushed material is determined by the adjustable crushing settings and the suitability of the selected jaw tooth profile. The adjustable wedge system allows multiple adjustments of the crushing settings. The components of the entire adjustment system are easily accessible, require low maintenance and can be easily replaced in case of severe wear.

What are application fields of jaw crusher?

Mining Industry

Jaw crushers are common in the mining industry and are used to crush large rocks into smaller particles. It can be used to crush iron, copper, gold, silver and other ores. Reducing the size of ores before processing and refining helps to separate valuable minerals from waste rock, making valuable materials easier to extract and process. Also in the coal industry, jaw crushers are used to crush coal before it is processed and transported to power plants or other end users.

Quarrying Industry

In the quarrying industry, jaw crushers are used to break large rocks into smaller particles that can crush stone, concrete and asphalt, and these crushed materials can be used in construction projects.

Construction Industry

Jaw crushers are also widely used in the construction industry for crushing concrete, asphalt and other materials, and these materials can be used in road construction and building projects. Particularly for material recycling, jaw crushers are capable of crushing old concrete and asphalt into smaller particles that can be reused in new construction projects.

Recycling industry

In the recycling industry, the jaw crusher is used to crush concrete, asphalt and other building materials. It is also used to crush a wide range of materials such as glass, plastics, metals, paper, etc. for the production of new products. For materials that are difficult to recycle, such as e-waste and construction waste, the jaw crusher can also effectively break them down.

Advantages and Disadvantages of Jaw Crushers

Advantages

• High efficiency: the jaw crusher adopts the principle of extrusion crushing, together with the high-frequency reciprocating motion of the eccentric shaft and the movable jaw, it can achieve a processing capacity of up to hundreds of tons per hour. In open pit mining scenarios, a single large jaw crusher can operate continuously for more than 12 hours, quickly crushing the mined raw ore to the initial particle size, providing a stable supply of material for the subsequent crushing process and significantly improving overall production efficiency.
• Versatility: With jaw plates made of high manganese steel or chromium-molybdenum alloy steel, the machine is able to cope with granite, basalt and other hard ores up to 7 on the Mohs hardness scale, as well as abrasive materials such as construction waste and ceramic waste. In metallurgy, building materials, highway construction and other industries, the jaw crusher can be flexibly adapted to the crushing needs of various types of materials by replacing the lining plate of the crushing chamber with one made of different materials, and it has become the core equipment for cross-field applications.
• Simple structure: the whole machine mainly consists of four major components: frame, movable jaw assembly, eccentric shaft, and elbow plate, which reduces the number of precision components such as gear drive and hydraulic system compared with the complex models such as cone crusher. This design makes it possible to focus only on basic maintenance items such as jaw plate wear and bearing lubrication during daily inspections, and companies can train ordinary workers to complete equipment inspections through standardized operation manuals, significantly reducing the reliance on professional maintenance.
• High cost-effectiveness: under the same capacity conditions, the purchase cost of jaw crusher is 20%-30% lower than that of impact crusher, and the motor-driven system is more energy efficient, with the energy consumption per unit of treatment controlled at 1.2-1.8kW・h/t. Its wearing parts, such as jaw plate, elbow plate, etc., are highly versatile and sufficiently supplied, with the cost of a single replacement about 1/3 of the cost of wearing parts of cone crusher, and the cost of a single replacement about 1/3 of the cost of wearing parts of cone crusher, and the cost of a single replacement about 1/3 of the cost of wearing parts of cone crusher. The cost of a single replacement is about 1/3 of that of a cone crusher, which saves a lot of operating expenses during the whole life cycle of the crusher.
• Adjustable size:Through the wedge-shaped adjusting device or shim adjusting system, users can flexibly set the discharge opening size within the range of 10-150mm. In the production of sand and gravel aggregate, the operator can quickly reduce the discharge opening from 80mm to 30mm according to the project requirements, precisely controlling the particle size of the finished product to meet the grading requirements of different concrete ratios and realizing refined production.

Disadvantages

• Frequent maintenance: Although the basic maintenance process of the jaw crusher is relatively simple, under heavy working conditions such as mining and large quarry plants, the equipment operates under high load for a long period of time, and the wear and tear of key components such as movable jaws and bearings are aggravated. In order to maintain crushing efficiency and safety, it is usually necessary to carry out a weekly comprehensive inspection, monthly replacement of lubricating grease, and quarterly in-depth overhaul of the transmission system. This high-frequency maintenance not only increases the cost of labor and consumables, but also leads to an average annual downtime of more than 50 hours, which directly affects the production schedule and economic benefits.
• Abrasive material wear:When processing quartz stone, granite and other high hardness, high abrasive materials, jaw crusher jaw plate, liner plate and other metal working surfaces will be due to continuous impact and friction, rapid flaking, grooves and other wear phenomena. Measured data show that when dealing with materials with hardness coefficient f=12-14, the service life of the jaw plate is only 3-6 months, while it can be 1-2 years under normal working conditions. Frequent replacement of worn parts not only increases the purchase cost, but also requires specialized personnel to work with the lifting equipment for replacement, which further pushes up the complexity of maintenance.
• Dust generation: During the crushing process, the material is extruded and impacted by the high-speed splash dust, the main component of which contains free silica and other harmful substances. If no effective control measures are taken, the dust concentration in the operation area can be as high as 50-100mg/m³, far exceeding the national occupational health standard (8mg/m³). Long-term exposure to the environment significantly increases the risk of pneumoconiosis among operators. At the same time, dust spillage can also cause ecological problems such as soil crusting and vegetation withering in the surrounding area, leading to the risk of environmental regulatory penalties.
• Noise generation: When the jaw crusher is in operation, the periodic impact of the movable and fixed jaws, and the mechanical vibration of the motor and transmission device will generate noise pollution as high as 90-105 dB. This high-intensity noise not only seriously interferes with the normal communication and operation of the site personnel, but also may lead to hearing damage, insomnia and other occupational diseases after long-term exposure. When working in environmentally sensitive areas such as residential areas and schools, noise exceeding the standard is more likely to cause complaints from the neighboring residents and face administrative penalties from the environmental protection department.
• Limited feed size: The feed size of the jaw crusher directly determines the maximum size of the material that can be processed, for example, the maximum feed size of the PE600×750 model is only 500mm, and when it comes to the huge rocks commonly found in mining, or the oversized concrete blocks produced by building demolition, the material must be reduced in size by blasting, hydraulic crusher, and other pre-processing means, which undoubtedly increase the size of the material, and thus reduce the size of the material. This undoubtedly increases the preliminary operation and cost investment, and reduces the overall crushing efficiency.

9 Tips To Improve The Efficiency Of Jaw Crusher

Feed the right material

For even wear of the jaws and lower operating costs, distribute the ore evenly at the feeder inlet and fill the crushing chamber to ensure that the material is uniformly subjected to crushing forces.

Ensure adequate feed volume

During the normal use of the feeder, the amplitude can be adjusted within the rated amplitude range by adjusting the control box knob according to the need of productivity, thus realizing the stepless adjustment of feeder productivity to meet different production needs.

Feeder Precautions

• Prevent iron pieces from entering the crushing chamber, which may damage the jaw plate and other parts, and in serious cases, lead to equipment failure.
• The height of the ore should not exceed the fixed jaw plate, so as not to affect the crushing effect and equipment operation.
• The maximum size of the raw material should be 75-100mm smaller than the feed opening of the jaw crusher. Too large size of the ore will easily block the crushing chamber and affect the crushing efficiency.

Setting the right size of discharge opening

Too small a discharge opening size will lead to clogging, consume too much energy and cause serious damage to the jaw crusher; too large a discharge opening size will increase the load of secondary crushing. Therefore, the size of discharge opening should be set reasonably on the basis of ensuring the raw material processing capacity.

Adjustment of discharge opening

There are two kinds of adjusting devices can be used to adjust the size of discharge opening: wedge-shaped adjusting device and gasket adjusting device. The wedge adjusting device adjusts the discharge opening size hydraulically, while the shim adjusting device adjusts the discharge opening size by changing the number of shims.

Jaw plate introduction

The two jaw plates are toothed, with straight segments designed to be inverted and interchangeable. Therefore, one jaw plate can be installed on both movable and fixed jaws, which prolongs the service life of the jaw plates and reduces the replacement cost.

Jaw plate wear state and treatment measures

The wear state of the jaw plate and its adjustment are very effective in improving the production capacity of the jaw crusher. Operators should regularly check the wear condition to determine when to invert, interchange and replace the jaws. The following are common wear conditions and measures to deal with them:

• The bottom of the movable jaw is worn 1/3 and the bottom of the fixed jaw is worn 2/3: Invert both jaws.
• The top and bottom of the movable jaws are 1/3 worn, the center section is half worn, and the top and bottom of the fixed jaws are 2/3 worn: turn both jaws upside down.
• Top and bottom of both jaws are completely worn: replace with new jaws.

Lubrication

Bearings are the core components of jaw crusher operation and are closely related to crushing performance. High-quality lubrication is the key to ensure the performance and service life of bearings, which should be lubricated regularly to reduce friction and wear.

Lubrication points and grease filling quantity

The eccentric shaft bearings mounted on the base bearing box and movable jaws are the only parts that require lubrication. The crusher is equipped with labyrinth seals to keep the grease inside the bearings clean. All four bearings are equipped with grease fittings for adding grease. Before adding grease, the grease nipple and grease gun should be cleaned to prevent dust from entering the bearing housing.

Jaw Crusher vs Impact Crusher

Jaw Crusher vs Cone Crusher

• Overall structure:Jaw crusher mainly consists of frame, transmission mechanism, adjusting device, tensioning device, safety device and lubrication system, the structure is relatively simple, mainly using compression force to crush hard stone, high crushing ratio; cone crusher mainly consists of frame, horizontal shaft, dynamic cone, balance wheel, eccentric sleeve, upper crushing wall (fixed cone), lower crushing wall (dynamic cone), hydraulic coupling, lubrication system, hydraulic system and so on. The cone crusher mainly consists of frame, horizontal shaft, dynamic cone, balancing wheel, eccentric sleeve, upper crushing wall (fixed cone), lower crushing wall (dynamic cone), hydraulic coupling, lubrication system, hydraulic system and so on.

• Feeding requirements:The feeding size of primary jaw crusher has a wide range, the feeding opening of large jaw crusher is more than 600mm, up to 1200mm, medium-sized is 300-600mm, and small-sized is below 300mm; the feeding size of cone crusher is relatively small, generally less than 450mm (depending on the specific conditions of the product).

• Finished product shape:Jaw crushers are usually used for primary crushing and have a large crushing capacity with a large output size but are suitable for the secondary crushing stage; cone crushers are used for the secondary and tertiary crushing stages and therefore have a smaller discharge size, the rock is continually crushed until it is small enough to pass through the narrow opening at the bottom of the cone crusher, and the final product is in good shape.

• Price: The price of a cone crusher is much higher than that of a jaw crusher due to wearing parts and construction. For the same output, the rotating body of a cone crusher is 2-3 times more expensive and 1-2 times heavier than a jaw crusher, making cone crushers more costly and more complicated to install and maintain than jaw crushers.

Key Factors for Selecting Unique Jaw Crushers

• Crushing capacity:Determine the required crushing capacity based on the expected output and production goals of the operation, and select a jaw crusher with sufficient capacity to handle the expected workload.
• Feed size: Evaluate the maximum size of the feed material to ensure that the jaw crusher can accommodate it effectively. Larger feed openings are better suited to handle larger rocks and achieve higher productivity.
• Adjustable output size: Considering the range of output sizes required for a particular application, the jaw crusher should have adjustable settings to control the desired size of the final product.
• Portability:Consider whether to choose a stationary or mobile jaw crusher, depending on the operational requirements. A mobile jaw crusher provides the most convenient setup for operations that require mobility.

Conclusion

As an important primary crushing equipment, the jaw crusher plays a key role in several industries such as mining, quarrying, construction and recycling. Its powerful crushing capacity, wide range of material adaptability and relatively simple maintenance features make it the first choice for many companies. However, it is also necessary to pay attention to its shortcomings, such as frequent maintenance, dust and noise problems, and take appropriate measures to improve them.

By choosing the type of jaw crusher reasonably and operating and maintaining it correctly, it can give full play to its performance, improve productivity and reduce cost. If you have the need for customized jaw crusher or want to know more information about related equipment, please feel free to contact us.

Frequently Asked Questions

What kind of materials can the Jaw Crusher process?

Jaw crushers can handle a wide variety of materials, including hard rocks (e.g. granite, basalt), ores (e.g. iron, copper, gold ores), recycled asphalt pavement (RAP), concrete, asphalt, glass, metals, and more.

How often do jaws need to be replaced?

The frequency of jaw replacement depends on the abrasiveness of the material, the amount of crushing and the conditions of use. Generally speaking, the wear of the jaw plate needs to be checked regularly, and when the wear reaches a certain level (as mentioned in the above wear condition and treatment measures), it should be inverted, interchanged or replaced in time.

Is mobile jaw crusher suitable for small projects?

Yes, mobile jaw crusher has the advantages of mobile flexibility and small footprint, which is very suitable for small projects or scenarios that require frequent moving of the operation site.

What is the difference between primary and secondary crusher?

Primary crusher is mainly used to crush large materials into smaller particles as the basis for subsequent crushing, jaw crusher is usually used as primary crusher; secondary crusher is used for further crushing of materials after primary crushing to achieve finer particle size requirements, such as cone crusher, impact crusher and so on are often used as secondary crusher.