1. What Is a Plate Hammer (Blow Bar)
In the heart of an impact crusher, the Blow Bar is the heavy-duty wear part fixed to the rotor.
- The Mechanism: As the rotor spins at high speeds (up to 1500 r/min), the blow bars strike the feed material with intense kinetic energy.
- The Impact Process: Crushing occurs in three stages: the initial blow bar strike, the impact against the Impact Plates, and material-on-material collision within the chamber.
What Is A Plate Hammer (Blow Bar)
2. Blow Bar Shapes and Fixing Methods
Blow bar design has a direct influence on wear life and crushing efficiency.
Common Shapes
- Bar type
- I-shape
- T-shape
- S-shape
- Hammer (axe) shape
The I-shape is commonly used for primary crushing to achieve deeper material engagement, while the S-shape is preferred for secondary crushing to maintain stable discharge size.
Fixing Methods
- Wedge Type:
Blow bars are fixed by wedge locking force. This design allows fast replacement and excellent stability at high rotor speeds.
- Bolt Type:
Used mainly in heavy-duty primary impact crushers to ensure secure fixing under extreme impact loads.
3. Material Selection: High Chrome vs. High Manganese
Correct material selection is critical for maximizing wear life. DUMA provides customized material solutions based on application.
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High Chrome Alloy (Cr26 / Cr27)
Suitable for highly abrasive and hard rocks such as granite and basalt. High hardness effectively resists micro-cutting wear.
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High Manganese Steel (Mn18Cr2)
Ideal for primary crushing. Under heavy impact, surface hardness rapidly work-hardens from HB 200 to over HB 500, while the core remains tough and crack-resistant.
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Ceramic Insert Composite
Ultra-hard ceramic inserts are embedded in high-wear zones, combining metal toughness with ceramic abrasion resistance. This is the optimal solution for extreme wear conditions.
4. About DUMA Machinery
DUMA Machinery is a direct manufacturer, not a trading company, operating an ISO 9001:2015 certified 42,000 m² integrated foundry and machining facility.
Our production covers the complete process from raw material inspection and casting to precision machining. With over 4,000 pattern sets, we ensure 100% dimensional compatibility for major brands including:
- Metso Nordberg NP Series
- Sandvik QI Series
- Terex Impact Crushers
- Every production batch undergoes:
- Metallographic structure inspection
- PT penetrant crack testing
This guarantees pure austenitic or martensitic structure with zero surface cracks, ensuring stable performance in mining and infrastructure applications.
Authoritative Technical References
- ISO 13503-2:2018 – International dimensional standards for impact crusher wear parts
- JB/T 13654-2019 – Technical requirements for cast impact crusher blow bars
- Taggart Handbook of Mineral Dressing – Classic reference on impact crushing mechanisms and energy transfer principles
