The NPK fertilizer granulator is the core equipment in the production of compound fertilizers; its operational stability directly determines product quality and production efficiency. Due to the complex composition and corrosive nature of NPK raw materials—combined with the equipment's constant operation under heavy loads—various faults occur frequently. These issues not only disrupt production continuity but may also increase raw material wastage and maintenance costs. Drawing upon practical production experience, the following analysis outlines the most common types of granulator faults and their primary causes, serving as a reference for equipment maintenance and troubleshooting.

Poor granule formation is the most frequent fault, manifesting as loose, brittle, or unevenly sized granules with rough surfaces—or, in severe cases, a complete failure of the material to agglomerate into granules. There are three primary causes for this: First, an imbalance in the raw material's moisture content—excessive moisture leads to sticking and clumping, while insufficient moisture results in a lack of binding force, making agglomeration difficult. Second, severe wear on the die rollers or improper adjustment of the roller gap, which prevents the generation of sufficient extrusion pressure, resulting in granules with inadequate density. Third, an irrational raw material formulation—specifically, an excessive proportion of fine powders or an insufficient proportion of binding agents—which compromises the effectiveness of granule formation.
Machine clogging is another persistent production issue. It typically occurs at the feed inlet, within the die holes, or in the gaps between the scraper blades, manifesting as material accumulation and blockage, a sudden surge in motor current, and—in severe cases—the triggering of the overload protection system, resulting in an emergency shutdown. The main causes include inadequate raw material pretreatment (e.g., the presence of metallic foreign objects or excessive coarse particles); die holes that have not been cleaned for extended periods and have become clogged with solidified material; and an excessively high feeding rate that exceeds the equipment's processing capacity, leading to material accumulation.
Abnormal equipment operation is also a common problem, specifically manifesting as the motor failing to start, excessive noise and vibration, or an overheating main shaft. Motor startup failures are often attributed to material accumulation within the granulation chamber, electrical circuit faults, or malfunctions in the limit switches. Noise and vibration typically stem from damaged bearings, improper die roller gaps, or the presence of foreign objects inside the equipment. Excessive heating of the main shaft is most frequently caused by insufficient bearing clearance or inadequate lubrication.
Furthermore, issues such as insufficient output volume and an excessively high proportion of fine powder in the finished granules are also relatively common; these issues are closely linked to an unstable steam supply, excessive wear on the die rollers, or an improper ratio of recycled material. In fact, most malfunctions can be prevented through standardized operating procedures—such as regularly cleaning die holes, inspecting components for wear, and controlling the moisture content and mixing ratios of raw materials. By mastering these common faults and their underlying causes, operators can rapidly diagnose issues, minimize downtime, and ensure the efficient and stable operation of the NPK fertilizer production line.