During plastic granulation production, various issues frequently arise, directly impacting particle quality and the stability of subsequent extrusion processes. The following analysis addresses common problems, identifies their causes, and proposes corresponding solutions for rapid troubleshooting and production optimization.
I. Pellet Appearance & Morphology Issues
01. Rough, Dull Surface with Pitting:
Cause: Incomplete plasticization (low temperature settings or insufficient shear force); Excessive moisture in raw materials (plastic, fillers like CaCO₃, or hygroscopic additives not fully dried); Improper lubrication system (excessive lubricant, especially external lubricant causing delayed plasticization; imbalance between internal/external lubricants); Equipment issues (severe screw wear, insufficient compression ratio, or weak shear force); Insufficient die head pressure (melt not dense enough).
Solution: Appropriately increase temperatures in plasticizing and homogenization zones; Ensure thorough drying of all hygroscopic components; Adjust lubricant system (reduce external lubricant, balance ratio); Inspect and replace worn screws if necessary; Increase melt density using finer mesh screens, adjusting die pressure bolts, or slightly reducing feed rate.
02.Pellet Sticking/Agglomeration:
Cause: Insufficient cooling (cooling water temperature too high or cooling time too short, pellet core not fully cooled); Static electricity buildup on pellet surface; Lubricant issues (excessive lubricant, especially external, or exudation); Cutter problems (dull blades or improper gap adjustment causing burrs); High ambient humidity.
Solution: Lower cooling water temperature (recommended 10-25°C), extend cooling bath length, or adopt more efficient cooling methods; Install ionizing air bars after cutting or at the vibrating screen; Select compatible, non-exuding lubricants; Sharpen/replace cutters and adjust gap; Reduce production environment humidity as much as possible.
03.Irregular Pellet Size with Tailing:
Cause: Unstable feeding (material bridging, feeder malfunction, or feed rate fluctuation); Melt pressure/temperature instability; Speed mismatch (cutter speed, main screw speed, and haul-off speed not synchronized); Cutter problems (worn, dull, or loose blades); Die plate issues (clogged die holes or inconsistent hole diameter due to wear causing uneven output).
Solution: Ensure consistent feeding; Precisely control temperature to stabilize melt pressure/temperature; Coordinate cutter, screw, and haul-off speeds; Regularly replace or sharpen cutters and ensure secure installation; Thoroughly clean die holes, inspect for wear, and replace die plate if necessary.
04.Chared Specks on Pellet Surface:
Cause: Carbonized material trapped inside screw; Material overheated for too long (leading to aging and charring).
Solution: Disassemble screw for thorough cleaning; Reduce heating time, inspect and repair any heating system faults.
II. Pellet Internal Structure & Performance Issues
01.Incomplete Plasticization (Unmelted Material, White Specks):
Cause: Insufficient temperature (plasticizing zone set too low); Screw problems (poor design or severe wear, insufficient compression ratio, weak shear force); Lubricant hindrance (excessive external lubricant impeding plasticization); Residence time too short (screw speed too fast or feed rate too high); Poor filler dispersion (e.g., CaCO₃ not fully wetted and dispersed).
Solution: Increase plasticizing zone temperature to required level; Evaluate/replace screw if worn or poorly designed; Reduce external lubricant, consider increasing internal lubricant or adding plasticization aids; Reduce screw speed or feed rate to extend plasticizing time; Optimize mixing process to ensure thorough filler wetting and dispersion.
02.Bubbles or Pores in Pellets:
Cause: High moisture content in raw materials (plastic, fillers, or regrind); Excessive volatiles (use of low-boiling plasticizers, lubricants, etc.); Processing temperature too high (localized overheating causing slight decomposition and gas generation); Poor die design (sudden excessive pressure drop at die head); Poor venting (vacuum venting system not operational or vents blocked).
Solution: Thoroughly dry all moisture-prone materials; Minimize volatile additives; Avoid localized overheating to prevent thermal decomposition; Ensure smooth melt pressure decay in die head; Ensure vacuum venting system functions correctly (clear ports, maintain vacuum).
03.Poor Thermal Stability (Yellowing, Black Specks, Yellow Streaks):
Cause: Inappropriate or insufficient stabilizer; Excessive processing temperature (overall too high or localized overheating - faulty temp control, high screw speed causing shear heat); Prolonged exposure to high temperature (die blockage, excessively fine or clogged screens causing material stagnation); Material buildup/decomposition in dead spots (screw, barrel, die wall, screen plate back); Excessive impurities or degraded material contamination.
Solution: Select suitable stabilizer type and dosage; Reduce barrel/die temperatures and shear heating; Prevent stagnation (clean die/screens regularly, avoid prolonged low-speed operation); Eliminate dead spots and clean equipment thoroughly; Ensure clean feedstocks and strictly control regrind quality/ratio.
III. Kitech Machinery Recycling Granulation Equipment: A Highly Effective Solution
By systematically analyzing root causes and implementing targeted solutions, plastic granulation quality and production stability can be significantly enhanced. If you continue to struggle with persistent granulation problems and cannot produce satisfactory plastic pellets, Kitech Machinery's recycling granulation equipment offers an excellent solution. We possess a professional technical team, dedicated sales support, and comprehensive after-sales service, ensuring your complete satisfaction both before and after purchase.
Plastic pellets produced using Kitech Machinery equipment exhibit superior characteristics:
Uniform Size: High consistency in pellet dimensions.
Consistent Color: Even distribution of color throughout the pellets.
Excellent Appearance: Smooth surface, free of bubbles.
Compliance: Fully meets all standards required for recycled plastic manufacturing.
IV. Commitment to a Greener Planet
As a trailblazer in plastic recycling technology, Kitech Machinery empowers industries worldwide with smarter, sustainable solutions. Our mission? To turn the tide on plastic waste-efficiently, profitably, and responsibly."
Plastic Pelletizing Machine: Turn scraps into premium-grade pellets with precision efficiency.
Plastic Recycling & Washing Machine: Transform contaminated plastics into ready-to-reuse flakes.
Shredders & Crushers: Crush bulky waste effortlessly for seamless downstream processing.
Squeezer & Dryers: Applied for drying LDPE industry film/bag and PP woven bags - perfect for high-moisture plastics!
Contact us team for an initial discussion. We are committed to producing the best quality products at the most competitive prices.
Email: remond@kitechpm.com
Contact Us: https://www.kitechrecycle.com/contact-us
