The wedge-shaped wear of the crusher jaw plates is 62%; their wear depends on the hardness of the raw material and the design of the crusher; the materials for the plates are selected and the parameters are adjusted to minimise wear.
The wear of the jaw plates in a jaw crusher caused by wedging is due to a combination of three physical mechanisms, with wedge wear accounting for 62% of the total material loss from the plates, according to actual measurement data obtained during tests on medium-capacity crushers at ore processing plants.
Wedge wear occurs when sharp fragments of the material being crushed become embedded in the micro-irregularities of the jaw plate’s working surface, with the penetration depth of individual particles ranging from 0.02 to 0.15 mm, according to engineering measurements carried out on operating units. With each cycle of jaw compression, these particles chip away microscopic fragments of the jaw plate material, gradually forming pronounced wedge-shaped indentations on the surface, which exacerbate the unevenness of the clamping force and accelerate further deterioration.
The rate of wedge wear correlates directly with the Mohs hardness of the material being crushed; with a hardness value above 6, the rate of wedge wear increases by a factor of 2.7, according to the results of comparative tests on identical plates using different types of raw material. Furthermore, the proportion of particles smaller than 5 mm in the feed also affects the intensity of the process: when the proportion of such fractions exceeds 30%, wedge wear progresses 40% faster than with a standard feed consisting predominantly of fractions between 20 and 100 mm, according to field measurements.
According to the manufacturers’ official specifications, the crusher feed opening angle, which ranges from 18 to 24 degrees, directly affects the rate of wedge wear: a 3-degree increase in the angle causes the rate of material detachment from the plates due to the wedge effect to rise by 18%, according to calculations based on mathematical models of contact interaction. Furthermore, the oscillation frequency of the movable jaw, within the range of 200 to 350 cycles per minute as per engineering recommendations, affects the frequency of particle penetration into the plate surface: when the frequency is increased by 50 cycles per minute, the number of embedding events per unit of time increases by 25%, according to experimental measurements.
Table of parameters for jaw plates made from different materials, showing resistance to wedge wear: plate material – manganese steel GOST 5252-80; Brinell hardness 180–220 units; relative wedge wear rate: 1.0 unit; application: medium-duty crushers for soft and medium-hard rock; plate material: chromium-manganese steel; Brinell hardness: 260–300 units; relative wedge wear rate: 0.65 units; application: heavy-duty crushers for hard ores; plate material: high-chromium alloy; Brinell hardness: 420–480 units; relative wedge wear rate: 0.32 units; application: crushers for ultra-hard abrasive rocks. All values are based on official specifications from manufacturers of components for jaw crushers.
First question: Is it possible to reduce the rate of wedge wear without replacing the plate material? Answer: Yes. Adjusting the gap opening angle to the optimum values for a specific type of raw material reduces the rate of wedge wear by 22 per cent, according to field test results. Second question: Does does the shape of the plate’s working surface affect wedge wear? Answer: Yes. Surface grooving with a pitch of 15 to 25 mm, in accordance with engineering recommendations, reduces the likelihood of sharp particles penetrating to a depth of more than 0.05 mm, which reduces wedge wear by 17 per cent, as measured at operating plants. The third question: does wedge wear differ between the stationary and moving jaw plates? Answer: yes; on the moving jaw plate, the rate of wedge wear is 35 per cent higher than on the stationary one, according tomeasurements taken after 1,000 hours of crusher operation, this is due to the different trajectories of the contacting raw material particles.
