Crusher Jaw Plates

Why material selection is the most important thing?

According to statistics, the replacement cost of the wear parts of the crusher accounts for more than 40% of the production cost. The cost of replacement mainly includes the cost of new parts, the cost of replacing workers, and the marginal cost of downtime. Unsuitable material parts will cause the parts to not wearable and increase the frequency of replacement parts. It is a big loss. So it is important to select the right material for your jaw plates.

Material types for jaw plates

There are 4 types of jaw plates materials:

1. Manganese steel. Manganese steel, also called Hadfield steel or mangalloy, is a steel alloy containing 12-14% manganese. Renowned for its high impact strength and resistance to abrasion in its hardened state, the steel is often described as the ultimate work-hardening steel. There are some grades for manganese steel jaw plates:
   • Mn14Cr2 Jaw Plates. Mn14cr2 jaw plates are used in crushing soft stones. For example, it has a good life when crushing the easy and non-abrasive blasted rock, non-abrasive gravel, and non-abrasive round rock.
   • Mn18Cr2 Jaw Plates. Mn18Cr2 is the most popular material for casting jaw crusher jaw plates. This Mn18Cr2 jaw plates widely in crushing difficult and non-abrasive blasted rock, medium and non-abrasive,non-abrasive gravel, and non-abrasive round rock.
   • Mn22Cr2 Jaw Plates. Mn22Cr2 jaw plates are widely used in crushing hard and abrasive stones. Under our technology, span life is much better than normal.
2. Alloy steel. Alloy steel to cast small jaw crusher jaw plates. Normally, the weight of alloy steel jaw plates less than 2 tons. After the jaw plate is energized, it can achieve the function of magnetic separation of raw materials.
3. Microalloy steel. By adding some rare elements into manganese steel, the manganese steel jaw plate gets more good wearable and hardness. This kind of material is widely used in crush copper mine.
4. TIC inserts jaw plates. Qiming Casting uses some titanium carbide rods to insert the manganese body.

Crush different kinds of stones or ores, it needs different jaw crusher tooth types to suit. There are some popular jaw plate tooth profiles and uses.

•  Standard Tooth. It is suitable for both rock and gravel crushing; Wear life, power requirements, and crushing stresses in good balance; Typical factory installation.
• Quarry Tooth. Suitable for crushing Shot Rock in quarries; The flat teeth perform better with abrasive materials; (more wearable tooth material); Cause higher stresses and increase power requirements.
• Super Tooth. Suitable for general use and especially a good choice for gravel crushing; the Large mass and special design of the teeth gives long wear life and allows fine material flow down through the cavity along the grooves without wearing the teeth.
• Corrugated Recycling Tooth. Suitable for crushing concrete; Fine material flows easily through the cavity along the large grooves.
• Wavy Recycling Tooth. Suitable for crushing Asphalt, Material flows easily down through the cavity along the grooves without packing; Normally used in the small setting range with the intermediate plate.
• Super Grip Tooth. Suitable for hard and round natural rock crushing; Provides better grip and capacity; Fine material flows easily through the cavity along the large grooves; Wear life of the fixed and movable jaw dies in good balance.
• Wedge & Standard Tooth. Suitable for both rock and gravel crushing; Thicker lower end of the jaw die and the thinner upper end of the jaw die; Maximizes size of the maximum feed size of the cavity with the maximum nip angle; Wedge jaw die is the fixed one and the Standard jaw die is the movable one.
• Anti Slab Tooth. Special jaws designed to crush slabby sedimentary rock; Can also be used when recycling concrete and asphalt slabs.
• TIC Inserts Tooth. Special jaws designed to crush hard rock; Can also be used when recycling concrete, asphalt slabs, and the mining industry.

There are 4 tips for prolonging jaw plates working life.

1. To install the right material jaw plate. Based on crush material, you need to select the right material. Such as the Mn22Cr2 jaw plates suit for crushing hard stone.
2. To install the jaw plate correctly. When installing the jaw plate, we must make sure that the jaw plate is installed correctly and stable to make it contact well with the machine surface. Otherwise, the jaw plate is easy to be shifted during the working process, causing the jaw plate to collide with the inner wall of the machine and seriously damaged.
3. No blocking of materials. When the material jams the jaw crusher, the sliding of materials squeezed by the jaw plate is increased, which increases the jaw plate abrasion, and enlarges the nip angle that the materials blocking situation becomes more serious, forming a vicious cycle.  Therefore, it is necessary to forbid the blockage of the material in the machine and find the blockage to be cleaned in time.
4. The feeding size must be controlled strictly. The abrasion of material properties to jaw plate is obvious, so we should strictly control the feeding size. The oversized particles are forbidden to enter the machine. In addition, the feeding must be evenly, or else, it may lead the angle of discharging hopper of crushing cavity to become big, and the movable plate indirectly contacts with materials to damage the jaw plate.

There are two situations that need to change the jaw plates.

1. Economic benefits and costs. After a long time of running, productivity will decrease because of the wear of jaw plates. So we need to calculate the ratio of economic benefits and cost. If the loss can cover the jaw plate’s price, we need to consider changing jaw plates.
2. In order to prevent damage to the crusher parts, jaw plates need to be changed before they are worn through. Different kinds of jaw crushers have different situations. In some kinds of jaw crushers, jaw plates with a wedge retention design can wear to a thickness of 20-25 mm until they must be changed; In some other jaw crushers, jaw plates with locking wedges in the back can wear to a thickness of 60-65 mm until they must be changed. When to change jaw plates? It based on your jaw crusher wedge retention design.

Jaw crusher wear parts need to be changed following the correct procedures to avoid risks. Different kinds of jaw plates need different ways to change jaw plates.

Two-piece jaw die rotation and replacement

• Worn out jaw dies are removed from the bottom of the crushing chamber.
• Work hardened upper jaw dies are installed at the bottom of the crushing chamber.
• New jaw dies are installed at the top of the crushing chamber.

One-piece jaw die rotation and replacement

• After a new jaw dies installation, rotate the single-piece jaw dies when 30% of the tooth profile is worn.
• Rotate a second time when the tooth profile at the bottom of the jaw die is completely worn.

There are 13 steps to change jaw plates:

1. Prepare to work tools:600 live-mouth wrench, wire rope, hand hammer, mast, sledgehammer, electric welding, crane
2. Prepare new jaw plate
3. Stop the feeding and the operation of the crusher, pay attention to wearing insulated gloves to prevent wet hands and electric shock.
4. Remove the screw of the old jaw plate
5. Remove the side plate, loosen the side plate screws, and lift the side plates with the overhead crane
6. Remove the clamps and slowly remove the stationary plate clamps and place them next to them.
7. The welding hoisting ring is welded to the moving plate and the fixed plate respectively. Be sure to solder firmly to prevent bruises during lifting
8. Lift the jaw plate and start the crane to lift the moving plate and the fixed plate and transport it to the storage area of waste materials. It should be noted that there is a need for monitoring during the opening of the crane. There can be no people under the crane to avoid bruising, and the wire rope should be strong.
9. Lift the new jaw plate, and start the crane to hang the moving plate and the fixed plate separately.
10. Install the clamps, place the clamps in place, and tighten the screws.
11. Tighten the stationary plate screws and install the side plates.
12. Adjust the gap of the discharge port.
13. Start the jaw crusher and vibrate the mine for trial operation.

If planning to exchange wear plates (3100-0), cheek plates, deflector plate (3500-0), and/or support bars (3200-0) at the same time, please proceed to the instructions for those parts before installing the new jaw plate. Replace the support bar screws if they are broken. Remove the support bar and clean it carefully. It’s important that the contact faces of the jaw are clean. There are 13 steps for installing jaw plates.

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. Be aware of the weight of the jaw plate. Handle the jaw plate with care. The tackle should now be tight but not lifting 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.