The Ultimate Guide to Jaw Crushers: Definition, History, Types, and Future Trends

Construction of Jaw Crushers

Jaw crushers are heavy-duty machines that need to be constructed robustly. Typically, their main frame is made from cast iron or steel and connected with tie bolts. Modern versions might feature a main frame of welded mild steel plate.

The jaws of these crushers are usually made from cast steel and are equipped with replaceable liners. These liners are typically made from manganese steel or “Ni-hard,” which is a Ni-Cr alloyed cast iron. Using hard-liners is crucial not only to reduce wear but also to minimize crushing energy consumption by limiting the deformation of the surface at each contact point. The jaw plates are bolted in sections, allowing for easy removal or periodic reversal to ensure even wear.

Cheek plates are installed on the sides of the crushing chamber to protect the main frame from wear. Like the jaw plates, these cheek plates are made from hard alloy steel and have similar lifespans. While jaw plates can be smooth, they are often corrugated, which is preferred for crushing hard, abrasive ores. The corrugated profile is said to perform compound crushing by compression, tension, and shearing, unlike conventional smooth plates that primarily crush through compression, though irregular particles under compression loading might still break in tension. Since rocks are much weaker in tension than compression, corrugated profiles are expected to lower power consumption and wear costs. Having some sort of pattern on the jaw plate surface is desirable in a jaw crusher to reduce the risk of large flakes slipping through the straight opening and to decrease the contact surface when crushing flaky blocks. A slight wave shape has proven successful in some installations.

The angle between the jaws is typically less than 26°, as a larger angle can cause particles to slip (not be nipped), reducing capacity and increasing wear. Curved plates are sometimes used to prevent choking near the crusher discharge, which can occur if fines are present in the feed. The lower end of the swing jaw is concave, while the lower half of the fixed jaw is convex, allowing for a gradual reduction in size as the material nears the exit, minimizing the chance of packing. This design also leads to less wear on the jaw plates, as the material is spread over a larger area.

The speed of jaw crushers usually ranges from 100 to 350 rpm and varies inversely with the size of the machine. The main criterion for determining the optimum speed is to allow particles enough time to move down the crusher throat into a new position before being nipped again.

History of Jaw Crushers

Jaw crushers have a rich history that dates back to the 19th century. They have evolved over the years, with key innovations in their design leading to improved efficiency and performance. Early jaw crushers were simple machines that relied on the power of human muscles to operate. However, with technological advancements, jaw crushers have become more efficient and powerful, capable of handling even the toughest materials.

What is a Jaw Crusher?

In the realm of crushing equipment, jaw crushers stand out for their formidable nature, often likened to “rock breakers.” Primarily used as primary crushers, these machines excel at breaking down some of the largest and hardest materials into more manageable pieces, ready for further reduction by other crushing equipment.

Types of Jaw Crushers:

There are two types of Jaw Crushers: Single Toggle and Double Toggle.

• Single Toggle: The single toggle movement jaw crusher, more compact than double toggle designs, was once unable to accept large feed sizes. However, technological innovations have solved this issue, making these machines popular for their speed. Although they experience more wear and tear than double toggle crushers, wear parts are widely available and economical, so this has not prevented the single toggle design from becoming popular.

• Double Toggle: Double-toggle movement jaw crushers have long been the standard for crushing hard and abrasive rocks and sticky feeds. These jaw crushers are highly energy efficient. The overhead pivot design further reduces wear and tear on the crusher.

How Jaw Crushers Work:

A jaw crusher is a primary crushing machine used in mining, construction, and demolition recycling industries. It operates by compressing rock between a fixed jaw and a moving jaw, which moves back and forth to create crushing action. This process breaks down large rocks into smaller, more manageable pieces. The fixed jaw of a jaw crusher acts as a sturdy frame, while the movable jaw exerts force on the rock by pressing it against the fixed jaw. The crushing action is achieved through the movement of the eccentric shaft, which causes the movable jaw to move back and forth. This movement is controlled by a toggle plate, which serves as a safety mechanism to protect the crusher from damage due to overloading or encountering uncrushable material. The size of the crushed material is determined by the gap between the two jaws, known as the discharge opening. By adjusting the discharge opening, operators can control the size of the crushed material, allowing for the production of different end products.

Benefits of Using Jaw Crushers:

Using jaw crushers in your operations can offer a wide range of benefits, improving productivity, efficiency, and profitability. Here are some of the key advantages of using jaw crushers:

• High Crushing Capacity: Jaw crushers are known for their high production capacity, allowing you to process large quantities of material efficiently. This is particularly beneficial in applications where a high throughput is required.
• Versatility: Jaw crushers are versatile machines that can handle various materials, from soft and friable to hard and abrasive. This versatility makes them suitable for various industries, including mining, construction, and recycling.
• Cost-Effective: Jaw crushers are cost-effective solutions for crushing applications. They offer a relatively low initial investment and require minimal maintenance, resulting in lower operating costs over the long term.
• Reduced Downtime: Jaw crushers are designed for high reliability and durability, minimizing downtime and ensuring continuous operation. This is crucial in industries where downtime can result in significant production losses.

Conclusion:

Jaw crushers are essential tools used in mining and construction industries to break down large rocks into smaller, more manageable pieces. They have evolved significantly, with technological advancements improving efficiency and performance. By understanding jaw crushers’ history, types, working principles, and future trends, we can appreciate their importance in various applications and industries.