In the fertilizer production field, granulular fertilizer packaging machines play a crucial role in the automated metering and filling of qualified granular fertilizer after granulation, drying, cooling, and screening to standard weights (typically 5-50 kg/bag). This equipment is specifically optimized for the physical characteristics of granular materials, such as good flowability and low dust content. Through the synergy of electronic weighing and PLC automatic control, granulular fertilizer packaging machines can maintain stable metering accuracy within ±0.1% to ±0.5% while packaging at high speeds. Packaging speeds can reach 180-720 bags/hour, making it the final key process in the fertilizer production line that transforms "semi-finished products" into "commodities." The equipment can be integrated with automatic feeders, sewing machines, conveyors, etc. to form an automated packaging production line, requiring only 1-2 people to operate on-site.
The granular fertilizer packaging machine adopts an integrated electromechanical design. The main components of the machine are as follows:
(I) Storage and Feeding System: This includes a storage hopper and a feeding device. The storage hopper is used to temporarily store the granular fertilizer to be packaged and is usually equipped with a level sensor to monitor the material level. The feeding device is a key component for controlling metering accuracy. Specifically designed for the good flowability of granular materials, it uses a pneumatic arc gate or vibrating feeder to achieve graded feeding. Graded feeding is divided into two stages: fast feeding first to improve efficiency, and then switching to slow, precise feeding when approaching the target value to ensure accuracy. The sensor provides real-time feedback signals to control the start and stop of the feeding mechanism.
(II) Weighing and Metering System: This is the core component ensuring the equipment's accuracy. It consists of a high-precision weighing sensor, a weighing hopper, a weighing control instrument, and an electronic control system. Depending on the model, either a weighing hopper or a suspended weighing method can be used. The sensor uses imported high-precision components, ensuring stable signal transmission. The weighing control system is designed according to the environmental requirements of fertilizer packaging workshops and has dustproof and waterproof functions. (III) Bag Clamping and Filling System: Includes pneumatic bag clamps and a hopper. The packaging bag is manually placed over the hopper, and the pneumatic bag clamp automatically clamps the bag opening, ensuring the bag does not detach or leak during filling. The hopper is rationally designed to ensure smooth flow of granular material into the packaging bag.
(IV) Conveying and Sealing System: Includes a belt conveyor and a sealing device (sewing machine or heat sealer). After filling, the packaging bag is conveyed to the sealing station. Sewing or heat sealing can be used depending on the bag material.
(V) Electrical Control System: Uses a PLC programmable controller as its core, equipped with weighing control instruments and an electronic control system. The system can store multiple formula parameters, enabling rapid switching between different product specifications. It features over-tolerance alarms, automatic error correction, automatic zeroing, and anti-interference functions.
Application range of equipment
The application areas of granular fertilizer packaging machines primarily focus on the fertilizer and agrochemical industries. In fertilizer production, it is suitable for quantitative packaging of various granular fertilizers such as compound fertilizers, blended fertilizers, BB fertilizers (blended fertilizers), urea, potash fertilizers, and phosphate fertilizers. In the agrochemical industry, it is suitable for packaging granular pesticides and seeds. In the chemical industry, it can be used for packaging materials such as plastic granules and chemical granules. The equipment can adapt to various packaging specifications from 5-50kg, meeting the diverse needs of fertilizer plants ranging from small and medium-sized to large-scale fertilizer production bases. The equipment can be used as a standalone unit or integrated with automatic feeders, conveyors, and sewing machines to form an automated packaging production line.
Types of available raw materials
Granular fertilizer packaging machines can process mainly granular materials. These include: Fertilizers: compound fertilizer granules, blended fertilizer granules, BB fertilizer granules, urea granules, potash fertilizer granules, phosphate fertilizer granules, organic fertilizer granules, etc.; Agrochemicals: granular pesticides, seeds, etc.; Chemicals: plastic granules, chemical granules, etc. The equipment utilizes the material's own weight and good flowability to achieve efficient feeding and metering. For materials that easily absorb moisture and clump (such as fertilizer granules), regular cleaning is necessary during equipment maintenance.
Working principle of the equipment
The working principle of the granular fertilizer packaging machine is based on the collaborative mechanism of electronic weighing and PLC automatic control. Its workflow is as follows:
(I) Feeding Stage: Material is conveyed from the storage hopper to the lower inlet via a feeding device. A pneumatic arc gate or vibrating feeder is used for graded feeding—initially rapid feeding to shorten the packaging cycle, then switching to slow, precise feeding when approaching the target value. Sensors provide real-time feedback signals to control the start and stop of the feeding mechanism.
(II) Weighing Stage: Material enters the weighing hopper (or directly into the packaging bag), and the weighing sensor monitors the weight change in real time. The sensor signal is processed by the weighing control instrument and transmitted to the PLC controller. When the set weight is reached, the PLC issues a stop feeding signal.
(III) Filling and Conveying Stage: After weighing, the material is filled into the packaging bag via the discharge hopper. The bag clamping mechanism keeps the bag opening tightly clamped during the filling process. After filling, the packaging bag is conveyed to the sealing station via a conveying device. (iv) Sealing stage: Depending on the material of the packaging bag, a sewing machine is used to sew and seal the bag, or a heat sealing machine is used to heat seal it. After sealing, the finished packaging bag is sent to the palletizing area by a conveyor device.
Equipment operation method
(I) Pre-start Preparation: Operators should be trained and familiar with the equipment structure and working principle before starting work. Check for loose screws in all parts. Check that the weighing sensor is installed horizontally and the wiring is secure. Check that the air source pressure meets the standard (usually 0.4-0.6MPa). Check that the power supply voltage is stable (within ±5%).
(II) Parameter Setting: Set the packaging weight and allowable error range through the human-machine interface or control panel. The system can store multiple formula parameters to achieve rapid switching between different product specifications.
(III) Operation: Manually place the packaging bag onto the feeding port. The bag clamping mechanism automatically clamps the bag opening. After startup, the system automatically completes feeding, weighing, filling, bag dropping, and conveying processes. During operation, the weighing data display should be monitored in real time to ensure stability.
(IV) Shutdown Operation: First, turn off the material supply, and after the hopper is emptied, turn off the main unit and disconnect the power. Maintain equipment usage and maintenance records and complete shift handover procedures.
Equipment maintenance methods
(I) Daily Maintenance: Clean residual materials and dust from the equipment after each shift. Check all fastening bolts for looseness. Pay attention to waterproofing, moisture-proofing, and corrosion prevention of electrical components; keep the electrical control box and wiring terminals clean.
(II) Periodic Maintenance: Perform a machine parts inspection at least once a month, checking the worm gear, worm shaft, bearings, and other moving parts for smooth rotation and wear. Regularly check the load cells and clean any accumulated material on their surfaces. Regularly calibrate the weighing system to ensure measurement accuracy.
(III) Electrical Maintenance: Check for loose or aging wiring terminals. Test the emergency stop button and photoelectric sensor sensitivity. Keep the inside of the electrical control box clean to prevent electrical faults.
(IV) Sealing Device Maintenance: Regularly check the working status of the bag sewing machine (or heat sealing machine) and replace worn needles or heating elements promptly.
Equipment troubleshooting
Inaccurate Measurement: Clean any adhering material from the sensor surface and check if the sensor is installed horizontally. Adjust the feeding speed and add a buffer device to reduce material impact. Recalibrate the weighing system using standard weights. Check for weighing parameter drift and recalibrate.
Insufficient Feeding: Stop the machine and clear any blockages. Check if the feeding device is jammed. Ensure a stable material level in the hopper.
Poor Bag Clamping: Check if the air source pressure is within the range of 0.4-0.6 MPa. Replace worn bag clamping seals. Adjust the bag opening positioning device.
Poor Sealing: Replace the sewing machine needle or adjust the heat sealing temperature. Regularly check the working status of the sealing mechanism.
