What should you do if your counterattack breaker hammer isn’t durable and wears out too quickly? Here are 7 factors that affect its lifespan—you need to know them!
2019-08-28
Loosening, fracture, and wear are all primary failure modes of impact crusher hammers, significantly reducing their service life and increasing component consumption. To cut production costs and enhance efficiency, it is essential for users of impact crushers to understand the root causes behind excessive hammer wear, enabling them to implement timely and effective countermeasures.
Generally speaking, the degree of wear and service life of hammer plates are directly related to factors such as the material of the hammer plates, manufacturing quality, hardness of the ore, the linear velocity of the hammer plates (rotor's peripheral speed), and the structural design of the plates—among which the material of the hammer plates is the primary factor determining the extent of wear.
01
The quality of the hammer bolt manufacturing is poor.
Some manufacturers of impact crushers still rely on outdated production processes, using bolted attachments to secure the hammerheads directly onto the rotor’s hammerhead seats. This conventional fixing method makes the bolts embedded in the hammerhead surface particularly vulnerable to shear forces exerted by the material being processed. If these bolts are also of poor manufacturing quality, they tend to loosen or even break frequently, significantly increasing the risk of hammerhead loosening, detachment, or fracture—and ultimately shortening the equipment’s service life.
Currently, large equipment manufacturers in China typically use either plate clamping or wedge locking. In the plate-clamping method, the plate hammer is inserted sideways into grooves on the rotor, and to prevent axial movement, pressure plates are used at both ends to secure it firmly. The wedge-locking method, on the other hand, involves wedges being driven into corresponding slots between the plate hammer and the rotor, ensuring a tight fit. This is currently considered one of the better methods for securing plate hammers, and it’s also widely adopted by manufacturers around the world.
02
Improper selection of hammer material
Common materials for counterattack breaking hammers include three types: high-manganese steel, alloy materials, and high-chromium cast iron.
Improper selection of the hammer material can lead to significant wear on the hammers. Therefore, it's crucial to carefully compare and choose the right material for your hammers during actual production. Each of the three materials offers distinct advantages: when crushing medium-hardness materials, high-manganese steel hammers are the ideal choice; while for harder materials, alloy-based materials such as chromium-molybdenum alloy cast steel are more suitable.
03
The manufacturing quality of the hammer is poor.
In the current market, the quality of counterattack hammers varies widely—some small manufacturers cut corners by using inferior materials during production, yet users can’t easily spot the difference based on appearance alone. As an editor, I once received a message from a friend who noticed, after his plate hammer broke, that the fracture revealed visible porosity and even voids, along with a noticeably coarse microstructure. This clearly indicates issues such as poor casting and heat-treatment quality.
04
Improper selection of the hammer structure
There are many types of hammer designs, with working surfaces available in both wide-and-thick and narrow-and-thin variations. The wide-and-thick design offers a larger effective wear area. Additionally, hammers can be single-head or double-head, as well as single-sided or double-sided. A single-head hammer has just one wear surface, while a double-head hammer features two wear surfaces—and a double-head, double-sided hammer boasts as many as four wear surfaces. Under the same material conditions, hammers with greater effective wear capacity and more wear surfaces naturally enjoy a longer service life.
05
The linear velocity of the hammer (the circumferential speed of the rotor)
The rotor speed can guide the selection of an appropriate rotational velocity for impact crushers when processing materials of varying particle sizes and compositions, helping to prevent over-crushing while also reducing energy consumption. Generally speaking, the higher the rotor speed, the greater the impact force generated during the collision between the hammer and the material, resulting in a larger crushing ratio. However, this also leads to increased wear on the hammers. Therefore, it’s crucial not to simply pursue high production output at the expense of excessive hammer wear. Instead, while still meeting production demands, the linear velocity should be minimized as much as possible to prolong the lifespan of the hammers.
06
The material does not meet the crushing requirements.
1) Impact crushers can typically handle materials such as granite, basalt, and limestone with particle sizes no larger than 350 mm and compressive strengths not exceeding 320 MPa. However, if operators fail to feed the material strictly according to crushing requirements—such as feeding excessively hard or oversized particles—the hammer plates may wear out too quickly.
2) If there is excessive sticky material, it will cause a large amount of material to adhere to the hammer plates, leading to overload operation and resulting in rapid wear of the hammer plates.
07
Improper use and maintenance
Due to the frequent breakage of hammer plates, operators have a heavy workload and high labor intensity when replacing them. As a result, after installing new hammer plates, they often become reluctant to stop the machine for inspections, leading to loose bolts that aren’t tightened promptly. This, in turn, can cause the hammer plates to come loose or even break. Proper maintenance plays a crucial role in extending the equipment’s lifespan—never neglect maintenance simply because you’ve already replaced parts.
In daily production, proper maintenance of the hammer plates should include:
1) Do not feed iron-containing materials. If you hear metallic knocking sounds or notice the ammeter indicating an overload, immediately stop the machine, remove any foreign objects, and carefully inspect all relevant rotating parts for damage before resuming operation and feeding material again.
2) Material-handling operations are prohibited during startup and shutdown;
3) Do not allow large materials (exceeding the maximum feed size specified in the manual) to enter the crushing chamber;
4) Feeding must be centralized and uniform (with material evenly distributed across the rotor);
5) Each shift must inspect the wear condition of the hammer plates, as well as the status of all bolts and their fasteners.
6) When installing, replacing, or adjusting the hammer plates, pay attention to their weight. Ensure that the weight difference between symmetrically positioned plates is kept as small as possible to maintain rotor balance before starting the machine.
7) Regularly inspect the wear condition of key machine components such as impact hammers, counterattack liners, and lining plates, and establish a systematic maintenance and replacement schedule aligned with the equipment overhaul cycle.
8) Be careful not to overload the machine, as this could cause significant damage and shorten its lifespan.
To reduce hammer wear and extend their service life, you can start with the seven points mentioned above: strictly control the manufacturing process of hammers, follow operational guidelines, and ensure proper equipment maintenance. This approach will help lower the frequency of hammer replacements to some extent, ultimately saving production costs and boosting overall business efficiency.
Duma Machinery's main products include: mantle and concave liners, crushing walls, and distribution plates for cone crushers; jaw plates, side guards, and pressure bars for jaw crushers; lining plates for ball mills, autogenous mills, and other equipment; impact crusher hammers and impact plates; as well as hammer heads, screen bars, liner blocks, and other wear-resistant alloy steel components for metal shredders.