Material selection of jaw plate of jaw crusher: dynamic analysis from working condition adaptability to performance upgrading

In the field of crushing operation, the material selection of jaw plate, the core vulnerable part of jaw crusher, directly determines the crushing efficiency, maintenance cost and operation continuity of the equipment. With the improvement of "high load, long cycle and low loss" demands for crushing equipment in mining and building aggregate industries, jaw plate material has been upgraded from traditional single type to "working condition customization and performance recombination". The following combined with the actual application scenarios and technical parameters to carry out the real and reliable material selection analysis.

From the perspective of the basic material classification, the mainstream jaw plate materials in the current market can be divided into three categories: high manganese steel, wear-resistant alloy steel and composite materials. The performance differences of the three types of materials and the applicable scenarios present a clear "working condition matching logic". Among them, high manganese steel (such as ZGMn13) is widely used in the working conditions with medium crushing hardness (such as limestone and dolomite) and less impurities in materials due to its excellent "work hardening" characteristics. When the high manganese steel jaw is impacted by materials, the surface will quickly form a hardened layer with hardness of HB500 or above, while the core remains good in toughness and can effectively resist impact fracture. Its casting process is mature and the cost is relatively controllable. So far, it is still the basic choice for medium and small-sized crushing production lines. However, it should be noted that when used to crush high hardness granites, basalts, or when the material is mixed with metal impurities, the hardened layer of high manganese steel is subject to rapid wear or local cracking, and the average service life is usually 300-500 hours, requiring frequent replacement.g.

For the crushing demand of high hardness and high abrasive materials, wear-resistant alloy steel (such as Cr-Mo alloy and high chromium cast iron) has gradually become the preferred choice for medium and large production lines. Taking Cr-Mo alloy jaw plate as an example, the hardness of matrix is increased to HRC50-55 by adjusting the content of chromium, molybdenum and other alloy elements, and at the same time, a certain tenacity is guaranteed by means of tempering treatment. When crushing granite, iron ore and other materials, manganese steel with high abrasion resistance is increased by 2-3 times, and the service life can be extended to 800-1200 hours. However, the high chrome cast iron forms M7C3 carbides with higher chromium content (15% - 30%), the hardness can reach over HRC60, the abrasion resistance is stronger, but the brittleness shall be improved through reasonable casting process (such as isothermal quenching), the fracture under impact shall be avoided, and it is more suitable for the "low impact and high abrasion" steady state operation scenes of fixed crushing station. It is noted that the processing cost of wear-resistant alloy steel is higher than that of high manganese steel, and it is generally recommended to use it in the high load scenario of "the monthly crushing capacity of single equipment exceeds 10000 tons" to balance the replacement frequency and comprehensive cost.

In recent years, the technical breakthrough of composite jaw plates (such as "high manganese steel matrix+wear-resistant alloy overlaying layer" and "ceramic particle reinforced metal matrix composite material") further fills the performance gap of traditional materials. Taking the overlay composite jaw plate as an example, the surface hardness of the overlay Cr-Ni-Mo alloy layer on the surface of the high manganese steel base plate can reach HRC55-60, and the core maintains the toughness of the high manganese steel, which not only solves the brittleness problem of the high chrome cast iron, but also improves the wear resistance of the high manganese steel. In the scene of "large material hardness fluctuation (such as mixed ore)", the service life of the overlay layer is increased by 1.5-2 times compared with the pure high manganese steel, and after the overlay layer is worn, the secondary repair welding can be carried out to reduce the replacement cost of consumables. While ceramic particle reinforced composite material improves the abrasion resistance by more than 30% by embedding alumina ceramic particles in the metal matrix. However, due to the complex forming process and high cost, it is temporarily used in the special ore crushing field with high requirements for crushing accuracy and loss control, which has not been widely used in a large scale.

From the core principle of material selection, dynamic matching shall be carried out around "material characteristics - equipment parameters - cost budget": if the crushed material is soft rock/medium-hard rock with Proctor hardness f=6-10 and the impact load of equipment is small, high manganese steel shall be preferred; If the material hardness f ≥ 12, or the abrasive property is strong (such as ore with high quartz content), and the equipment is heavy jaw (feed inlet ≥ 600mm), it is suggested to select wear-resistant alloy steel; If the material composition is complex, the hardness fluctuates greatly, or the "long-period maintenance-free" is pursued, the composite material is a better solution. At the same time, the material selection needs to be combined with the actual operation data - for example, when a limestone crushing production line adopts ZGMn13 jaw plate, it is replaced once a month, and the single cost is 8000 yuan; Cr-Mo alloy jaw plate shall be replaced once every 3 months, with single cost of 18000 yuan. According to the calculation, the annual consumable cost is reduced from 96000 yuan to 72000 yuan, and the downtime for maintenance is reduced to indirectly increase the production capacity.

In the future, with the promotion of the concept of "green crushing", jaw plate materials will also develop towards the direction of "recyclability and low alloying" - for example, research and development of low nickel and high manganese steel will reduce the dependence on precious metals while ensuring the performance; Explore the material regeneration technology after the decommissioning of jaw plates to reduce the production of industrial solid wastes. For users of crushing equipment, it is suggested to select materials through "small batch trial+data tracking". For example, first purchase small jaw plates of different materials for 1-2 months of working condition test, record wear rate, crushing efficiency, replacement cost and other data, and then determine the optimal material scheme in combination with long-term production plan to avoid blindly pursuing "high abrasion resistance" and ignoring cost adaptability, so as to really realize "dynamic balance between material performance and operation demand".