Dose-Feeding Plastic Pelletizing Machine

The dose feeding pelletizing line is an integrated system for producing uniform plastic pellets, combining precise feeding, melt extrusion, water cooling, pelletizing, and drying processes. Unlike traditional pelletizing lines with separate equipment, this integrated system minimizes material loss (≤2%) and ensures consistent pellet quality by synchronizing parameters across all units (e.g., feeding speed, extrusion temperature, pelletizing speed). It is equipped with a centralized control system that automates the entire production process—from raw material input to finished pellet packaging—making it ideal for plastic raw material production, recycling, and masterbatch manufacturing.

Product Features

Feeding System: Twin-screw dose feeder (with precision screw pumps) offering ±0.5% metering accuracy, supporting 2-4 component material mixing (e.g., PVC resin + plasticizer + stabilizer). The feeder’s hopper is equipped with a level sensor and automatic refilling alert, preventing production interruptions due to material shortage.

Extrusion Unit: Single-screw extruder with L/D ratio 33:1 (optimized for plastic melting) and a heating system with 5 temperature zones. It achieves stable melt pressure of 15-25MPa—ensuring uniform plasticization and reducing pellet density variation (≤0.03g/cm³). The extruder’s barrel is made of 38CrMoAlA steel (nitrided) for wear resistance, with a service life of 8000+ working hours.

Pelletizing Technology: Rotating knife pelletizer (with 6-12 high-speed steel blades) featuring 3000rpm maximum speed, producing pellets with diameter 2-6mm (length-diameter ratio 1:1-1:2). The pelletizer’s cutting chamber is water-cooled to prevent blade overheating, ensuring clean cuts and minimizing pellet burrs (burr rate ≤1%).

Drying Module: Vibrating fluidized bed dryer (with adjustable air distribution) that reduces pellet moisture content to ≤0.1%—critical for preventing defects in subsequent processing (e.g., bubbles in injection molding). The dryer uses hot air at 60-80℃ (with energy recovery system) to reduce energy consumption by 15% compared to conventional dryers.

Applications

Plastic Raw Material Production: Manufactures high-quality PP, PE, and PVC pellets (meeting ISO 1873-1 standards) for use in injection molding, extrusion, and blow molding industries. The line’s high precision ensures consistent pellet size and density, enabling downstream manufacturers to achieve stable product quality.

Recycled Plastic Processing: Converts plastic scraps (e.g., film, pipes, bottles) into high-quality pellets with recycling efficiency up to 98%. The line’s melt filtration system (equipped with a 120-mesh filter) removes impurities (e.g., dust, metal particles) to improve pellet purity, making recycled pellets suitable for food-contact or high-end applications.

Masterbatch Production: Produces color masterbatches (with pigment content 10-50%) and functional masterbatches (e.g., anti-UV, flame-retardant, antistatic). The twin-screw feeder ensures uniform additive dispersion (dispersion degree ≥95%), preventing color streaks or uneven functional performance in the final product.

FAQ

Q: What is the pellet size tolerance of this line?

A: The size tolerance is controlled within ±0.1mm, meeting international plastic pellet standards such as ISO 1873-1. Customized pellet shapes (e.g., cylindrical, spherical, oval) are available with specialized die heads, with a 1-week lead time for die customization.

Q: How long does it take to change the pellet size?

A: With quick-change knife and die sets (equipped with positioning pins for easy alignment), the changeover can be completed within 30-60 minutes for standard size adjustments (e.g., from 3mm to 5mm). For major size changes (e.g., from 2mm to 6mm), additional adjustments to the pelletizer speed and cooling system may extend the process to 2 hours.

Dosing System: Firstly, pour the plastic material into the hopper, and then start the motor through the control system to drive the screw to rotate. The screw will support the material is sucked into the hopper and then pushed to the feed inlet of the extruder.

Extruder: After being pushed into the barrel of the extruder, the material becomes molten through heating and pressure. At this point, the screw of the extruder begins to rotate forward, extruding the molten plastic through the die into shape. At the same time, the extruder's dose feeding machine will continue to continuously transport plastic materials to the extruder's feed inlet, maintaining a certain production capacity.

Water ring cutting machine: 

When the material passes through the second extruder, it will form a strip into the water ring cutting machine. In this device, strips of material are cooled and cut into predetermined size particles in water. The role of water is not only to cool, but also to help stabilize the cutting process and take away the cutting heat.

Dewater machine: The particles after cutting through the water ring contain a certain amount of water, so it is necessary to remove these excess water through the dehydrator.

Vibrating Screen: Used for screening solid waste and recycling materials, promoting the classification and recycling of waste.

Silo: The function of a silo is to store the materials produced. It can provide a suitable storage environment to ensure the quality and safety of the materials.

Final product: PP PE pellet