Crusher Jaw Plates

Selecting the appropriate material for the wear parts of the crusher is crucial as it accounts for over 40% of the production cost. Replacement cost includes the cost of new parts, workers, and downtime. Poor quality parts lead to frequent replacements, making it a big loss. Therefore, it is vital to choose the right material for jaw plates.

There are four types of materials for jaw plates:

1. Manganese steel, containing 12-14% manganese, is known for its high impact strength and resistance to abrasion in its hardened state. It comes in three grades:

-Mn14Cr2: used for soft stones like non-abrasive blasted rock and round rock

-Mn18Cr2: the most popular material for casting jaw crusher jaw plates, suitable for difficult, medium, and non-abrasive blasted rock, gravel and round rock

-Mn22Cr2: ideal for crushing hard and abrasive stones, with a longer span life than normal

2. Alloy steel, used to cast small jaw crusher jaw plates. It weighs less than 2 tons and is magnetically charged to separate raw materials.

3. Microalloy steel, which combines manganese steel with rare elements to enhance its hardness and wear resistance. It is suitable for crushing copper mines.

4. TIC inserts jaw plates, where some titanium carbide rods are inserted into the manganese body.

Different types of stones or ores require different jaw crusher tooth types for effective crushing. There are various jaw plate tooth profiles that are popularly used in crushing applications.

The Standard Tooth is ideal for crushing both rock and gravel. It offers a balanced combination of wear life, power requirements, and crushing stresses, which makes it a typical factory installation.

The Quarry Tooth is suitable for crushing Shot Rock in quarries. Its flat teeth perform better with abrasive materials and are made from more durable tooth material. However, it causes higher stresses and increases power requirements.

The Super Tooth is a versatile option and an excellent choice for crushing gravel. Its large mass and special teeth design provide long wear life and allow fine material flow down through the cavity along the grooves without wearing the teeth.

The Corrugated Recycling Tooth is ideal for crushing concrete. Its large grooves allow fine material to flow easily through the cavity.

The Wavy Recycling Tooth is suitable for crushing Asphalt. It allows material to flow easily down through the cavity along the grooves without packing and is typically used in the small setting range with the intermediate plate.

The Super Grip Tooth is ideal for hard and round natural rock crushing. It provides better grip and capacity and allows fine material to flow easily through the cavity along the large grooves. The wear life of the fixed and movable jaw dies is in good balance.

The Wedge & Standard Tooth is suitable for both rock and gravel crushing. It has a thicker lower end of the jaw die and a thinner upper end of the jaw die, which maximizes the size of the maximum feed size of the cavity with the maximum nip angle. The Wedge jaw die is the fixed one, and the Standard jaw die is the movable one.

The Anti-Slab Tooth is a special jaw designed to crush slabby sedimentary rock. It is also useful for recycling concrete and asphalt slabs.

Finally, the TIC Inserts Tooth is a special jaw designed to crush hard rock. It can also be used when recycling concrete, asphalt slabs, and the mining industry.

There are four tips for prolonging the working life of jaw plates:

1. Install the right material jaw plate: Based on the material being crushed, you need to select the right material for the jaw plate. For example, the Mn22Cr2 jaw plates are suitable for crushing hard stones.

2. Install the jaw plate correctly: When installing the jaw plate, it is important to ensure that it is installed correctly and stably to ensure good contact with the machine surface. Otherwise, the jaw plate may shift during the working process, causing it to collide with the inner wall of the machine and become seriously damaged.

3. Avoid material blockage: When the material becomes jammed in the jaw crusher, the sliding of materials squeezed by the jaw plate increases, which increases the jaw plate abrasion and enlarges the nip angle, making the material blocking situation more serious. Therefore, it is necessary to prevent blockage of materials in the machine and clean any blockages in a timely manner.

4. Strictly control the feeding size: The properties of the material can cause abrasion to the jaw plate, so the feeding size must be strictly controlled. Oversized particles should not be allowed to enter the machine. Additionally, the feeding must be even to prevent the angle of the discharging hopper of the crushing cavity from becoming too large, which can indirectly damage the jaw plate by causing it to come into contact with the materials.

There are two situations that may require changing the jaw plates of a crusher. The first is related to economic benefits and costs. Over time, the productivity of a crusher may decrease due to wear and tear on the jaw plates. In such cases, it is important to evaluate the ratio of economic benefits to costs. If the loss suffered due to decreased productivity outweighs the cost of replacing the jaw plates, then it is advisable to consider changing them.

Secondly, changing the jaw plates in a timely manner can prevent damage to the crusher parts. The frequency with which jaw plates need to be replaced depends on the design of the jaw crusher. For example, jaw plates with a wedge retention design can typically wear to a thickness of 20-25 mm before they need to be replaced, while those with locking wedges in the back can wear to a thickness of 60-65 mm before replacement is necessary. It is important to understand your jaw crusher’s wedge retention design in order to determine when it is time to replace the jaw plates.

It is important to follow correct procedures when changing the wear parts of a jaw crusher to avoid any potential risks. Different types of jaw plates will require different methods for replacement.

For a two-piece jaw die rotation and replacement, the worn out jaw dies should be removed from the bottom of the crushing chamber. Work-hardened upper jaw dies should then be installed at the bottom of the crushing chamber, followed by installing new jaw dies at the top of the chamber.

For a one-piece jaw die rotation and replacement, the single-piece jaw dies should be rotated after 30% of the tooth profile has worn, and then rotated again when the tooth profile at the bottom of the jaw die is completely worn.

There are 13 steps to follow when changing jaw plates, which include preparing the necessary tools such as a 600 live-mouth wrench, wire rope, hand hammer, mast, sledgehammer, electric welding, and crane.

To begin, the feeding and operation of the crusher should be stopped, and insulated gloves should be worn to prevent electric shock from wet hands. The screw of the old jaw plate should be removed, and the side plate should be loosened and lifted with an overhead crane.

The clamps should be removed, and the stationary plate clamps should be slowly taken off and placed nearby. The welding hoisting ring should then be welded to both the moving plate and the fixed plate, ensuring a firm solder to prevent bruises during lifting.

The jaw plate should be lifted, and the crane should be started to lift the moving plate and the fixed plate and transport them to the waste material storage area. It is important to monitor the crane during this process to avoid any injuries, and the wire rope should be strong.

The new jaw plate should then be lifted, and the crane should hang the moving plate and the fixed plate separately. The clamps should be installed, placed in their proper position, and tightened with screws.

Finally, the stationary plate screws should be tightened, and the side plates should be installed. The gap of the discharge port should be adjusted before starting the jaw crusher and vibrating the mine for trial operation.

If you are planning to exchange wear plates (3100-0), cheek plates, deflector plate (3500-0), and/or support bars (3200-0) simultaneously, please refer to the instructions of those parts before installing the new jaw plate. If the support bar screws are broken, replace them. Remove the support bar and clean it meticulously. It is essential to ensure that the contact faces of the jaw are clean. There are 13 steps to follow for installing jaw plates, which are as follows:

1. Clean the wear plate (3100-0), support bar (3200-0), and corners of the crushing chamber.

2. Position the hook of a mobile crane vertically above the new jaw plate (3300-1).

3. Hang the lifting tool (2) (provided with the crusher) on the hook of the mobile crane and attach the hook of the lifting tool to the lifting cavity (1) on the new jaw plate (3300-1).

4. Take up the slack in the lifting tackle, keeping in mind the weight of the jaw plate. Handle the jaw plate with care. The tackle should now be tight, but it should not lift the jaw plate. Keep clear of hanging loads.

5. Carefully lift the jaw plate (3300-1) into the crushing chamber.

6. Place the jaw plate (3300-1) on the support bar (3200-0).

7. Adjust the jaw plate (3300-1) into its correct position.

8. Place a crowbar between the jaw plate (3300-1) and the deflector plate (moving jaw) (3500-0) or front frame end (stationary jaw).

9. Slacken off the lifting tackle.

10. Remove the hook of the lifting tool (2) from the lifting cavity (1).

11. Pack a sponge rubber strip or rags into the lifting cavity (1) to keep out dust.

12. Remove the crowbar.

13. Put two props between the jaws to fix the jaw plates in place until the clamping bars above are installed.

• The wear ratio: Fixed jaw > movable jaw>lower cheek plate>upper cheek plate
• The working time: 1 Fixed jaw= 1.5 Movable jaw= 3 Lower cheek plate= 6 Upper cheek plate
• Usually, the fixed jaw wears the fastest.