Disc granulator
The disc granulator is a powder granulating equipment with a rotating inclined disc as the core working component. This equipment processes powdery raw materials into uniform spherical particles through the process of rolling, adhesion and growth of materials in the plate. The equipment has outstanding advantages such as high granulation rate (up to more than 93%), round particles, intuitive operation, and easy maintenance. It is one of the most popular mainstream granulation equipment in organic fertilizer, compound fertilizer and other industries.

Structural Composition of the Disc Granulator

From an operation and maintenance perspective, the structure of the disc granulator can be divided into the following functional modules:

(I) Working Module—Granulating Disc: Comprises the disc body, rim, and lining. The disc body features an integral arc structure reinforced by multiple radial steel plates at the bottom; the rim height determines the material capacity within the disc; the lining is made of high-strength fiberglass (FRP) or stainless steel, ensuring corrosion resistance and durability.

(II) Power and Transmission Module: Consists of an electric motor, gearbox, pulleys, pinion gear, and main gear. The main gear is fixed to the bottom of the disc, while the pinion meshes with it to drive the disc's rotation. A flexible belt drive is employed to ensure smooth startup.

(III) Adjustment Module: Includes an angle-adjustment screw rod and locking nuts for adjusting the disc's inclination angle; some models are equipped with a variable-frequency drive (VFD) to adjust the rotation speed, accommodating the granulation requirements of different materials.

(IV) Cleaning Module: Includes a scraper assembly, non-powered scrapers, a bottom scraper, and a rim-corner scraper; an automatic cleaning mechanism prevents material from adhering to the disc walls.

(V) Support Module: Comprises the frame, base, and main shaft. The base is thickened and weighted, eliminating the need for anchor bolts and simplifying installation.

Maintenance Methods for Disc Granulators

Maintenance for the disc granulator should be scheduled on a daily, weekly, monthly, quarterly, and annual basis.

Daily maintenance: Before startup, check the lubrication of the drive mechanism and bearings, and add the specified lubricant; after shutdown, promptly clear residual material from the disc to prevent hardening or caking. During operation, perform predictive checks by observing the running status, listening for abnormal sounds, and touching bearings to monitor temperature.

Periodic maintenance: Weekly calibration of the scraper clearance and disc flatness is required, with timely replacement of worn parts; apply high-temperature grease to the main gear weekly. Conduct a comprehensive structural inspection monthly, tightening loose bolts and checking the drive system for abnormal noises. The main bearing housing requires regreasing every 5–6 days.

Shutdown maintenance: Stop feeding material before shutting down; allow the granulating disc to idle for 5 minutes to clear out remaining material before cutting the power. Following major overhauls or prolonged periods of inactivity, conduct a 2-hour no-load test run to check the rotation direction and monitor for periodic noise or vibration; proceed to a 4-hour heavy-load test only after the no-load run proves normal.

Lubrication management: The temperature rise of the main bearing should not exceed 25°C, and the temperature rise of the reducer lubricant should not exceed 20°C. Use the specified lubricants for different components. Maintain a clearance of 5–10 mm between the scraper and the disc bottom, and a gap of 2–5 mm between the side scraper and the disc rim.

Common issues with the equipment

(I) Low pelletization rate and uneven granules: Characterized by excessive powder in the final product, inconsistent granule sizes, and poor sphericity. This is the most common issue; causes include incorrect material moisture content, improper adjustment of the disc's inclination angle or rotation speed, and severe scraper wear.

(II) Disc misalignment and abnormal operating noise: Manifests as unstable operation, wobbling, or unusual sounds. Primary causes include uneven wear on support wheels, loose mounting bolts, lack of lubrication or bearing damage, and excessive gear backlash due to wear.

(III) Overheating bearings: Characterized by excessively high temperatures (hot enough to burn the touch) at the reducer or main unit bearings, often accompanied by abnormal noise. This is usually caused by poor lubrication or bearing wear.

(IV) Intermittent operation or sudden shutdown: The equipment does not run continuously, stopping and starting sporadically. This is generally caused by bearing failure, loss of balance in the disc assembly, or abnormal motor voltage.

(V) Material clogging: Impurities such as stones or plastic fragments mixed into the raw material can get stuck at the edge of the granulating disc, causing clogs that severely impact production efficiency.

Solutions to Equipment Problems

Solutions for the aforementioned malfunctions are as follows:

Low pelletizing rate: First, check the material moisture content; if too high, spread the material out to air-dry for 1–2 hours, and if too low, evenly spray with water or a binding agent. Check the particle size of the crushed raw materials and re-crush any that do not meet specifications. Stop the machine to adjust the disc inclination angle (45°–55° is ideal), making incremental adjustments of 5° and testing the operation after each change. Inspect the scraper for wear; replace it if wear is severe, and adjust the clearance to 3–5 mm during installation.

Disc misalignment: Stop the machine and inspect the support wheels; replace those with severe wear and smooth out those with minor wear. Tighten all mounting bolts and adjust the support wheel height to ensure the disc rotates horizontally. Feed material evenly to prevent accumulation on one side.

Bearing overheating and abnormal noise: Stop the machine immediately for inspection and replenish or replace the lubricating oil or grease. Replace the bearing immediately if it shows signs of seizing or wear. For abnormal noise at gear meshing points, clear away surface debris; apply grease for minor wear, or replace the gears if wear is severe.

Material clogging: Screen raw materials to remove impurities such as stones and plastic fragments before feeding; maintain material moisture within the appropriate range.

In summary, the core approach to troubleshooting the disc granulator is to "identify the cause first, then apply the specific remedy," while daily maintenance focuses on "lubrication, cleaning, and parameter control." Most malfunctions can be resolved on-site through simple procedures, significantly reducing downtime.