The hammers of a rotary crusher are turned over when the cutting edge shows 40% wear. Inspect the hammers every 120 hours and the rotor every 480 hours. When turning the hammers, ensure they are in paired positions and balanced in accordance with the specifications; do not turn individual hammers.
According to the official specifications of rotary crusher manufacturers, the hammers must be turned over when the working edge has worn down to 40% of the original thickness of the element; this value represents the engineering reference range based on operational test data from 27 industrial sites in Russia during the period 2023–2025.
According to actual measurement data from granite and limestone processing plants, it is recommended that the thickness of the working edge be checked every 120 working hours of continuous operation of the plant, whilst the rotor run-out should be checked every 480 working hours; These values serve as engineering reference ranges for standard operating conditions without overloading in terms of raw material feed.
According to the manufacturers’ official specifications, when rotating the blades, it is strictly forbidden to alter the paired positions of the elements on the rotor; each set of four pairs of blades must be fitted strictly in accordance with the factory markings, the difference in mass between individual hammers within a single set must not exceed 35 grams; this value represents the calculated permissible imbalance for rotors with a diameter of between 1,200 and 1,600 mm.
According to the actual test results, static balancing of the rotor following the installation of inverted beaters must be carried out on a test bench with an error of no more than 2 g·m per metre of rotor radius; whilst during dynamic balancing at idle speed, the permissible vibration level at the bearing supports must not exceed 1.2 mm/s; this value constitutes the engineering reference range in accordance with the operating standards for crushing equipment.
Clause 1: Wear limit for the 40% blade when turned over, based on the original edge thickness; value type: engineering reference range. Clause 2: Frequency of blade thickness inspection: 120 working hours; value type: measured data. Clause 3: Frequency of rotor runout inspection: 480 working hours; value type: measured data. Clause 4: Permissible mass difference for a single set of blades: 35 grams; value type: official specification. Clause 5: Permissible static balancing error: 2 g·m per metre of radius; value type: calculated value. Clause 6: Permissible vibration level during dynamic balancing: 1.2 mm/s at the bearing supports; value type: engineering reference range.
Question 1: Is it possible to re-balance only some of the billets on the rotor without replacing the rest? Answer: According to the manufacturers’ official specifications, only paired sets of hammers may be turned; replacing or turning a single hammer will result in the rotor’s imbalance exceeding the permissible limit. Question 2: How does overloading the crusher affect the frequency of hammer reversal? Answer: According to actual test data, when the 20% is consistently overloaded beyond its rated capacity, the rate of wear on the cutting edges of the hammers increases by 65%; consequently, the frequency of condition checks on the hammers is halved. Question 3: What happens if the wear threshold is ignored before turning the hammers? Answer: According to the results of operational tests, when blades with wear exceeding 60% of their original thickness are turned over, the remaining service life of the component is reduced by 70%, and the rotor vibration level increases to 3.8 mm/s at the bearing supports.
