LaiZhou ChengDa Machinery Co., Ltd.

As key granulation equipment in industries such as feed, biomass fuel, and pharmaceuticals, the maintenance cycle of pellet mills directly affects production efficiency and equipment lifespan. A reasonable maintenance schedule can effectively reduce fault-related downtime and ensure stable operation of the production line.

Daily Maintenance (Required Every Shift)

Daily maintenance is the foundation of pellet mill upkeep. Before each startup, operators must check whether lubrication is sufficient in key areas such as the main shaft, roller presses, and gearbox, verify that rotating components are not loose, and ensure the gap between the die and roller press is adjusted to the standard range of 0.1–0.3 mm. After each shutdown, all residual material in the feeding auger, conditioner, and inner wall of the ring die must be thoroughly cleaned to prevent carbonization and die hole blockage. At the same time, the electrical wiring connections should be inspected for firmness, and abnormal noise or vibration should be identified to ensure the equipment is in normal condition.

Weekly Maintenance

Weekly maintenance focuses on the inspection of the transmission system and wear-prone components. The roller press bearings need to be disassembled, cleaned, and refilled with high-temperature-resistant grease. The tension of the main motor belt should be checked, and the feeder speed should be calibrated. Meanwhile, the wear condition of the ring die's inner wall should be inspected; if the hole diameter expands by more than 10%, timely replacement is required. In addition, the travel safety switch and paddle wear should be examined, all connecting bolts should be tightened, and particular attention should be paid to checking the wear degree of transmission keys and clamping hoops.

Monthly Maintenance

Monthly maintenance involves a more in-depth inspection of the pellet mill's internal systems. A mixture of soybean meal, fine sand, and grease should be run through the machine for 20–40 minutes to polish the inner wall of the ring die. Worm gears, worm shafts, bearings, and other moving parts should be checked for smooth rotation, unusual noise, or signs of wear. The fan and feed pipes should be cleaned to ensure smooth material conveying. The wear depth of the roller press should be measured, and if it exceeds 0.5 mm, it should be replaced promptly. At the same time, the insulation performance and wiring firmness of the electrical system should be checked to ensure electrical safety.

Quarterly to Semi-Annual Maintenance

The quarterly to semi-annual maintenance cycle mainly targets the lubrication system and transmission components. The lubricating oil in the reduction gearbox needs to be replaced, with the oil level kept at the midpoint of the oil gauge. A comprehensive inspection of the transmission system should be carried out, and the overload protection threshold of the electronic control system should be verified. Motor synchronous belts should be inspected and replaced if necessary, with tension properly adjusted. Dust should be cleaned from the distribution box, and the operating status of the frequency converter and the tightness of wiring terminals should be checked. The auger shaft and conditioner transmission bearings need to be disassembled, cleaned, and maintained to ensure smooth transmission.

Annual Maintenance

Annual maintenance is a comprehensive overhaul of the pellet mill. The entire equipment should be inspected to assess the wear condition and service life of all components. Filters and pipelines should be replaced, and all filters should be cleaned. The electrical system should undergo a thorough inspection, with aging, damaged, or corroded electrical components and wiring replaced. Equipment precision should be calibrated to ensure that pellet quality during production meets standards. The main motor needs to be completely disassembled and cleaned internally, the anti-rotation locking block should be checked for effectiveness, and clearances between various components should be adjusted.

Special Requirements for Lubrication Management

Lubrication management is the core element of pellet mill maintenance. Main shaft bearings and transmission bearings use grease lubrication; during continuous operation, high-temperature grease should be added every 8–12 hours, and the grease should be completely replaced after 500–800 cumulative operating hours. For the gearbox reducer, new oil should be replaced after the first 100–200 hours of operation, and thereafter every 1,500–2,000 hours or every 3–6 months. Roller press bearing housings and adjustment pins should be greased every 24–48 hours, and the old grease should be thoroughly cleaned and replaced with new grease after 800–1,000 cumulative operating hours.

Production-Based Maintenance Intervals for Key Components

In addition to time-based cycles, maintenance of key components should also be carried out according to processing output. The roller press must be inspected for wear after processing every 500–600 tons of raw material, and mandatory replacement is required after 800 tons. For dies, organic fertilizer granulation dies should be replaced after 4,000–5,000 tons of cumulative processing, while biomass granulation dies made of Cr12MoV material can be used for 6,000–8,000 tons before replacement. The automatic oil injection pump should be checked for unobstructed oil lines every 200 hours to prevent bearing damage caused by dry grinding.

In summary, the maintenance cycle of pellet mills should be carried out in five tiers—daily, weekly, monthly, quarterly to semi-annual, and annual—while also performing specialized maintenance on key components based on processing output. Establishing a standardized maintenance record sheet to track key parameters such as lubrication timing and clearance values can effectively extend equipment service life, reduce failure rates, and lower production costs.