Flat Die Pelleting Machine

Equipment Introduction

A flat die pelleting machine, also known as a flat film pelletizer, is a dry pelletizing machine based on extrusion molding technology that processes powdery or fibrous materials into cylindrical pellets. It is mainly used in organic fertilizer production, feed processing, biomass fuel manufacturing, and agricultural waste treatment.

This equipment adopts a conical wheel flat die structure and a screw center pressure adjustment mechanism, which can adapt to the pressing requirements of different materials by adjusting the die gap. The core pressure roller assembly adopts a multi-uniformly distributed structure, possessing the characteristics of pressure resistance, wear resistance, and stable operation. The flat die pellet mill can produce cylindrical pellets with a diameter of Φ1.5-Φ50mm, with a low temperature rise during processing (<30℃), which can better preserve the internal nutrients of the raw materials.

The flat die pelleting machine features low investment cost, wide applicability, simple operation, and low energy consumption, making it the preferred pelletizing equipment for small and medium-sized organic fertilizer plants, feed processing plants, and biomass fuel enterprises.

Equipment Structure

Main Frame & Machine Frame

1. Material: Constructed from high-quality carbon steel or alloy steel, treated with anti-corrosion powder coating or electrostatic spraying, providing vibration resistance, corrosion resistance, and a long service life.

2. Flat Mold (Die)

Material: Alloy steel or wear-resistant casting; common thickness 20–35 mm, hole diameter (2–10 mm) and hole type (round, elliptical, polygonal) can be customized according to material hardness.

Replacement Method: Bolt-fixed for easy and quick disassembly and maintenance.

3. Pressure Rollers

Structure: Double or triple pressure roller layout; roller surface treated with high-frequency welding or overall quenching, achieving a hardness of HRC50 or higher.

Adjustment: Mechanical or hydraulic adjustment of the roller die spacing to ensure optimal pressure.

4. Transmission System

Composition: Three-phase asynchronous motor + gear reducer + coupling + pulley.

Features: Emphasis on transmission efficiency (>95%), low noise (<75 dB), equipped with air cooling or oil cooling.

5. Feeding and Discharging System

Feeding: Vibrating feeder or screw feeder to maintain uniform and continuous feeding.

Discharging: Reamer type or fixed-length cutter; blades are made of alloy steel or tungsten carbide; easily worn parts can be quickly replaced.

6. Auxiliary Devices

Lubrication System: Centralized automatic lubrication pump + distributor, delivering high-grade grease at regular intervals;

Dust and Slag Removal: Bag filters or cyclone dust collectors can be installed at the inlet and outlet to ensure workshop cleanliness.

Equipment Compatible Raw Materials

The flat die pelleting machine boasts excellent material compatibility, adapting to various powdery, flocculent, and finely crushed materials with a moisture content of 20%-40% and free of hard, large impurities. Specific categories include:

1. Livestock Feed Raw Materials: Corn flour, soybean meal, wheat bran, rice bran, fish meal, bone meal, premixes, hay powder, straw powder, bran cake, etc., suitable for producing livestock and poultry feed, aquatic feed, and pet food. It is also suitable for forming high-fat and high-molasses formula feeds.

2. Organic Fertilizer/Agricultural Raw Materials: Livestock and poultry manure (chicken manure, sheep manure, cow manure), straw fragments, sawdust, mushroom residue, biogas residue, humus, wood ash, oilseed cake, and other fermented organic materials. It is the core forming equipment for small-scale organic fertilizer production lines.

3. Biomass Energy Raw Materials: Wood chips, bamboo powder, rice husks, peanut shells, straw powder, and other finely crushed biomass powders, suitable for producing biomass fuel pellets and heating pellets.

4. Light Industry and Chemical Auxiliary Raw Materials: Loose powder materials such as small-scale chemical powders, feed additives, trace element powders, fertilizer additives, and desiccant raw materials.

Key Raw Material Compatibility Parameters:

Material Fineness: 20-100 mesh fine powder/flocculated material;

Material Moisture Content: 20%-40% (optimal range 25%-35%);

Prohibited Materials: Stones, iron blocks, hard large impurities (easily damage mold rollers).

Equipment Applications

Flat die pelleting machines are widely used in the following fields:

In the feed industry, flat die pelleting machines can gelatinize starch and denature proteins, improving feed digestibility and palatability. The pellets have a smooth surface and high hardness, facilitating storage and transportation. In the biomass energy sector, loose sawdust and straw can be compressed into high-density fuel pellets, increasing density from approximately 500 kg/m³ to over 1100 kg/m³, significantly improving calorific value.

Equipment Working Principle

The core principle of the flat die pelleting machine is low-temperature dry extrusion compaction molding. The entire process involves no high temperatures, no drying, and no chemical reactions; it's purely physical and mechanical molding. 

The complete workflow is as follows:

1. Material Feeding: Pre-treated powdery and loose materials are evenly conveyed to the surface of the horizontal flat die by the feeding mechanism, naturally spreading out in the die hole area by gravity.

2. Compaction and Extrusion: The motor drives the main shaft through a reducer, causing the pressure rollers to roll at a uniform speed. The pressure rollers apply high-intensity mechanical pressure to the material on the die surface, crushing and breaking up material clumps, while simultaneously forcibly extruding the material into the flat die hole.

3. Degassing and Compaction: During low-speed extrusion, the air inside the material is fully expelled, and the material molecules tightly bind together, forming high-density, high-strength columnar strips.

4. Fixed-Length Pelletizing: The columnar strips penetrating the die hole are continuously extruded from the bottom of the die. The high-speed cutter at the bottom automatically cuts the material to a set length, forming uniform cylindrical solid particles.

5. Finished Product Output: The cut granules are conveyed to the discharge port via a slinger. After preliminary screening to separate fine powder, finished granules are obtained. Unqualified powder can be recycled for secondary granulation.

Core Advantage Principle: Low-temperature molding fully preserves probiotics, organic matter, nutrients, and active substances in the material, making it particularly suitable for granulating heat-sensitive materials. This is a core advantage that high-temperature granulation equipment cannot replace.

Granulation Process of Equipment

The granulation process of a flat die pelleting machine consists of the following stages:

The die orifice structure has a significant impact on granulation quality. Standard die orifices are straight holes of uniform diameter; to reduce extrusion resistance, tapered inlets can also be used. The effective thickness of the die orifice (working length) must be matched to the material characteristics and target particle density.

Flat die granulation is a short-process, low-energy-consumption, and fewer-step forming process. The standardized and complete process flow is as follows: raw material screening and impurity removal → material crushing and refining → material moisture content adjustment and stirring → uniform feeding → flat die extrusion forming → fixed-length pelletizing → finished product screening → pellet drying/air drying → finished product packaging → powder recycling and secondary granulation.

Compared to ring die granulation and wet granulation processes, it eliminates high-temperature drying, spray humidification, and complex conditioning processes, shortening the process flow by more than 40%, requiring less space, and reducing operating costs, making it particularly suitable for small to medium-sized mass production scenarios.

Application of Equipment in Production Lines

Flat die pelleting machines are typically used as core granulation equipment in production lines, forming a complete production line in conjunction with upstream and downstream processes.

1. Typical Flow of an Organic Fertilizer Production Line

Raw material fermentation → Drying (optional) → Crushing → Mixing → Flat die granulation → Drying → Cooling → Screening → Packaging → Finished product

Flat die granulators are used to granulate various fermented organic fertilizers. Before granulation, the raw materials do not need to be dried or crushed; they can be directly mixed to produce cylindrical granules, saving a significant amount of energy.

2. Typical Feed Production Line Flow:

Raw material crushing → Ingredient mixing → Flat die granulation → Cooling → Screening → Packaging

3. Typical Biomass Fuel Production Line Flow:

Raw material crushing (wood chips, straw, etc.) → Drying → Flat die granulation → Cooling → Screening → Packaging

4. Process Characteristics:

The process flow is relatively simple; the initial stage only requires crushing and simple mixing of materials.

The pellet temperature at discharge is relatively low, which is extremely beneficial for bio-fertilizers, preserving the activity of beneficial microorganisms as much as possible.

No heating or drying is required; the pellets are formed in one extrusion process.

Features include no return material, high pellet strength, and low moisture content.

Common Equipment Faults and Solutions

1. No Particle Output, Clogged Die Holes

Causes: Poor die hole smoothness in new die, excessively low material moisture content, rust clogging the die holes, excessive gap between the pressure roller and die; Solutions: Clean residual hard lumps from the die holes; repeatedly grind the new die with oil-containing powder; adjust the material moisture content to the standard range; recalibrate the roller-die gap to 0.1-0.3mm.

2. High Powder Content in Particles, Loose Formation, and Fragile

Causes: Excessively high/low material moisture content, excessive coarse fiber content, insufficient extrusion pressure, severe die wear; Solutions: Precisely adjust the material moisture content; add viscous powder to mix the material; increase the extrusion pressure of the pressure roller; replace worn or aged die.

3. Reduced Equipment Capacity and Slow Particle Output

Causes: Wear and slippage of the pressure roller and die, uneven feeding speed, partial blockage of the die holes, insufficient transmission torque; Solutions: Grind or replace the pressure roller and die; adjust the variable frequency feeding speed; clear all die holes; check the reducer lubricating oil and motor condition.

4. Abnormal noise and machine vibration during operation

Causes: Loose bolts, damaged bearings due to lack of lubrication, uneven roller die clearance, hard impurities in the material; Solutions: Tighten all bolts; replace damaged bearings and add grease; recalibrate the clearance; screen materials to remove impurities.

5. Inconsistent particle length and quality

Causes: Loose or worn cutter, uneven feeding, unstable extrusion pressure; Solutions: Tighten and grind the cutter, adjust the feeding speed to be uniform, calibrate the pressure rollers.

6. Motor overload tripping and burnout

Causes: Excessive feeding at one time, severe blockage, short circuit due to phase loss, bearing jamming; Solutions: Stop the machine to clear blockages, control the feeding speed; repair the circuit, replace faulty parts.

Flat die pelleting machines, with their unique advantages such as simple structure, low investment cost, strong raw material adaptability, low-temperature extrusion, and one-time molding, have become core equipment for small-scale production in the three major fields of organic fertilizer, feed, and biomass fuel. Their core technology lies in the extrusion cooperation between pressure rollers and a flat die, which forces materials through die holes to form cylindrical granules. The equipment is simple to operate, requiring only ordinary workers and no specialized technicians; it also boasts low operating costs and convenient maintenance. Production capacity covers a wide range from 20 kg/h to 8 t/h.

If you have any questions about fertilizer production equipment and processes, or would like to learn more about customized solutions, please contact us immediately. Whether it's equipment selection and quotation, installation, commissioning and operation training, or after-sales maintenance and process upgrades, we can provide you with professional and timely answers and support, offering a full-process service.