Contents:

1. What are the impact crusher parts?

2. What is impact crusher blow bars?

• Crusher blow bars material types
• Which are the influencing factors on blow bars wear
• Some crusher blow bars working problems and solutions
• When to change crusher blow bars
• How to change crusher blow bars

3. Why choose Qiming Casting’s impact crusher parts?

What are the impact crusher parts?

Impact crusher is a kind of crushing machine that uses impact energy to crush materials. When the machine works, the rotor rotates at a high speed driven by the electric motor, and the material enters the plate hammer area, then crushes with the plate hammer on the rotor, and then is thrown to the impact device to crush again, and then bounces back to the plate hammer area from the impact liner to crush again. The material is discharged from the discharge port.

There are hundreds of parts in an impact crusher. Based on functions and exchange frequently, the common wear parts for impact crusher include:

• Apron liners
• Crusher blow bars
• Impact plates
• Spring
• Square steel
• Main shaft
• Locking block
• Compression block

What are impact crusher blow bars?

As an important component of horizontal shaft impact crushers, blow bars come into direct contact with material and provide a powerful impact force. HSI crushers and their blow bars are designed to fracture material quickly, resulting in high production rates and reduced costs-per-ton when compare to other types of crushers.

Crusher blow bars are thick slabs of metal, typically some mixture of chrome, that are cast for the purpose of effectively breaking apart material like asphalt, concrete, limestone, etc. Often in sets of 3 or 4, blow bars are inserted into an impact crusher’s rotor where they are able to strike material needing to be processed.

Crusher blow bars material types

There are five kinds of material that we used in manufacturing crusher blow bars. Different materials suit different impact crusher working conditions.

1. High Manganese. This material is widely used in crusher jaws, crusher cones and crusher shells,not common in impact crusher. However, when crushing less abrasive and large feed material(such as limestone), the manganese blow bars are the best choice.
2. Martensitic Steel. Martensitic steel lies between manganese and chrome steel. It’s used if the impact load is too little to harden the manganese steel, and good wear resistance is required along with good impact stress resistance.
3. Chrome Steel. Chrome steel is the common material in casting HSI blow bars because it has a very good hardness. Regularly, chrome steel typically has a hardness of 60 to 65 HRC. And if we increase the elements “Mo” content, it also can get very toughness and wearable, not easy break.
4. Metal Matrix Composites. This combination makes HSI blow bars very wear-resistant but at the same time very impact-resistant. With blow bars made of composites from the surface of ceramics, the working life can reach three to five times that simple martensitic steel blow bars.
5. Titanium Tungsten Alloy. In order to increase the span life of blow bars in different conditions, our foundry success to use titanium-tungsten alloy to cast crusher blow bars. Under this material, the span of life can reach more than 2 times compare to chrome steel blow bars.

Which are the influencing factors on blow bars wear

During material crushing in an impact crusher, wear is produced when the elements press against each other, such as liner, blow bars, and crushing material. During this process, small materials from each element become detached, causing the surface to wear away. The primary factor in wear for crushing applications is abrasion. Material fatigue is also a factor as the wear material is subjected to numerous pressure and impact stresses. There are several factors that influence the wear behavior of an impact crusher. The following some of the factors that affect the wear lifetime of crusher blow bars:

Material-related factors:

• Abrasiveness
• Breakability
• Grain shape
• Fine-particle proportion
• Moisture content
• The proportion of unbreakable elements

Machine-process-related factors:

• Crushing ratio
• The ratio of the upper to the lower impact toggle
• Rotor speed
• Type of loading
• Screening mesh of the prescreen
• Contamination in the crushing chamber

Operation-related factors:

• Continuity of feed
• Correct adjustment of machine parameters
• Replacement of wear parts in due time
• Selection of the right blow bars

Some crusher blow bars working problems and solutions

There are many reasons why your impact crusher blow bars are breaking on a regular basis. We have compiled a list of the most common causes of blow bar failure and the solutions to those problems.

 

Study case 1

Problem: Excessive penetration on the blow bar

Causes:

• The rotor speed is too slow.
• Increases risk of blow bar breakage.
• The blow bar is under-utilized before changing.
• Increased rotor wear.

Solution:

• Increase the rotor speed.
• Change to 4 high blow bars.

 

Study case 2

Problem: Poor penetration on the blow bar means the top of the blow bars is worn down flat.

Causes:

• The rotor speed is too high.
  • Wear rates will be excessive.
  • Reduced output.
  • Creates a lot of fines

Solution:

• Reduce the rotor speed.
•  Change configuration to 2 high and 2 low blow bars.

 

Study case 3

Problem: Wear on the sides of the blow bar

Causes:

• A high percentage of fines in the feed or overfeed causing fines to be pushed outside.
• Crusher chamber contaminated with caked material causing friction wear.

Solution:

• Reduce the speed of the feeder so wear becomes even across the surface of the blow bar.
• Clean chamber daily after each shift.

 

Study case 4

Problem: Blow bar wearing excessively to one side

Causes:

• The machine on uneven ground – material falling to one side
• The machine isn’t choke-fed.
• Feed dropped onto one side of the feeder when using a recirculating option.

Solution:

• Ensure the machine is on level ground.
• Continuous loading.

 

Study case 5

Problem: Blow bar is damaged or broken.

Causes:

• Incorrect blow bar for an application. (E.g. Chrome)
• There is steel or rebar in the feed.
• The feed size is too large.

Solution:

• Select the correct blow bar.
• Control feed size.
• Remove steel or rebar.

When to change crusher blow bars

There are 3 situations that need to change crusher blow bars:

1. Normal wear. In order to avoid damage to the rotor, blow bars should be replaced before they are worn through.
2. Blow bar break. When chrome blow bar crushes iron steel, it easily breaks; Some “problem” blow bars (Casting shrinkage cavity) also easily break; Other reasons results.
3. When one face is used, the blow bar can be turned around to use the other face.

How to change crusher blow bars

There are 6 steps to change crusher blow bars:

1. Open the impact crusher as per the instruction manual;
2. Switch off the system components and diesel generator;
3. Secure the rotor;
4. Visually inspect the wear limited on all blow bars;
5. Visually check the blow bars for cracks and protrusions;
6. Turn around or replace the blow bars as necessary

Notes on change crusher blow bars:

• For rough cleaning of crushing chamber, it is recommended to fill the crusher for several minutes with clean, coarse material;
• Always use suitable lifting gear and tack;
• At least two people should take part in installing and removing crusher blow bars;
• Improper replacement of the blow bars can lead to crusher damage;
• Completely extend the crusher gap before blow bar replacement in order to prevent a collision between the blow bars and toggle after new blow bars have been installed;
• Only operate the rotor if the blow bars have been correctly installed;
• Always replace blow bars in sequence;
• Before making the final setting, briefly operate the machine at the highest rotational speed, then check the wedge clamps; tighten the screws if necessary;
• Replace all blow bars even if only one of them broken;
• A non-secured rotor can lead to severe injuries, observe safety instructions;
• Always use conical spring washers with the clamping bolts of the tensioning devices. Retighten the clamping bolts after approx. two operating hours.

Why choose Qiming Casting’s impact crusher parts??

There are some reasons:

1. There are thousands of patterns that can be used, which can decrease the cost;
2. Qiming Casting supplies all the kinds of material can be chosen, which include manganese steel, chrome steel, ceramic inserts, TIC inserts, and alloy steel;
3. All of Qiming Casting’s impact crusher parts are backed by ISO9001:2015 quality control system;
4. Qiming Casting will supply complete quality control reports for customers.