The granulation process in a disc granulator is essentially the rolling of material along a fixed path on an inclined disc surface, where particles grow through the successive adhesion of material layers. This path is determined by the disc’s inclination angle, the verticality of the main shaft, and the levelness of the machine frame. When factories observe a drop in granulation efficiency or inconsistent particle size, the immediate reaction is often to adjust the rotation speed, change the inclination angle, or increase water spraying. However, they frequently overlook a more fundamental issue: whether the equipment foundation is level and the machine frame is sufficiently rigid. If the equipment is installed incorrectly, the actual inclination of the disc will not match the scale reading, causing the material to flow unevenly within the disc—a problem that cannot be corrected simply by fine-tuning the rotation speed.
If the foundation is not level, the disc’s inclination angle becomes a “false” setting. The inclination of an organic fertilizer disc granulator is typically set via an adjustment mechanism; a reading of 45° is only accurate if the machine’s base frame is perfectly level. If the foundation itself is sloped or the shims are not properly leveled, the actual inclination angle may deviate by 2° to 3°. On the side where the inclination is effectively shallower, the material layer becomes thicker and the residence time increases, resulting in larger particles. Conversely, on the side where the inclination is steeper, the material slides down more rapidly, leading to an excess of fine powder. This creates an uneven material distribution—thicker on one side and thinner on the other—which reduces granulation efficiency and causes uneven wear along the edge of the disc. This principle applies to all disc-type fertilizer granulators: since the inclination angle is defined relative to the horizontal plane, any lack of levelness in the foundation invalidates the reference point for all angle adjustments.
If the main shaft is not vertical, the material’s rolling path becomes elliptical. The main shaft of a disc granulator should be perfectly perpendicular to the disc surface. If the shaft’s verticality falls outside of tolerance during installation, the disc will exhibit “runout” (wobble) as it rotates. This causes the material inside the disc to be periodically tossed upward and dropped, disrupting the intended rolling trajectory. Instead of rolling into uniform, spherical granules, the material is “jolted” into flattened shapes or broken fragments. Long-term operation further exacerbates wear on the main shaft bearings and increases vibration in the reduction gearbox.
Insufficient frame rigidity and loose anchor bolts are “chronic issues.” During operation, a disc granulator is subject to persistent off-center loading; if anchor bolts are not tightened to the specified torque or lack anti-loosening measures, they will gradually loosen over the course of a few weeks. This causes the frame to vibrate periodically, leading to wobbling of the granulation disc and inconsistent particle sizing. In a disc granulation production line, the granulator is typically preceded by a feeder and followed by a screening and material-return conveyor system. Vibrations in the frame can propagate to this conveying equipment, causing the material discharge point to shift—which, in turn, further intensifies uneven material distribution within the disc.
Modern “two-in-one” granulators impose even stricter requirements on the foundation. These units integrate the mixing zone and the granulation zone onto a single frame; if the foundation is not level, the relative positioning of these two zones may shift. This results in uneven stress on the seals between the mixing and granulation sections, potentially allowing unmixed material to “short-circuit” directly into the granulation zone, thereby compromising the uniformity of the granules.
The troubleshooting process is straightforward: use a spirit level to calibrate the foundation before installation, employ shims for leveling, and then perform secondary grouting. During no-load operation, place a small amount of material on the disc surface and observe whether its rolling trajectory is symmetrical. Additionally, periodically re-verify the level of the frame and the torque of the anchor bolts. A disc granulator is not a piece of equipment that can simply be “placed on the ground and expected to run”; the levelness of the foundation is the prerequisite for all other process parameters. Ensure it is installed level first—only then should you proceed to fine-tune the operating parameters.