{"id":3541,"date":"2026-04-12T06:04:59","date_gmt":"2026-04-12T06:04:59","guid":{"rendered":"https:\/\/kitech-recycling.com\/?p=3541"},"modified":"2026-04-12T06:28:50","modified_gmt":"2026-04-12T06:28:50","slug":"plastic-pelletizer","status":"publish","type":"post","link":"https:\/\/kitech-recycling.com\/pt\/blog\/plastic-pelletizer\/","title":{"rendered":"Pelletizer pl\u00e1stico: Tipos, princ\u00edpio de trabalho & guia de sele\u00e7\u00e3o"},"content":{"rendered":"

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How Plastic Pelletizers Work: Types, Components & Buyer Selection Guide<\/strong><\/p>\n

While millions of tons of plastic scrap are generated every year as industrial byproduct or postconsumer waste, the process of converting that waste into a valuable raw material runs through the plastic pelletizer. This is the machine at the heart of any recycling line \u2014 one of the most critical recycling machines \u2014 which transforms molten or shredded scrap polymers into uniform pellets \u2014 raw materials ready for reuse in injection, blow, and film processing. This guide unpacks the working of pelletizing systems, compares the three main cutting technologies, takes you through process control considerations and provides a straightforward guide to selecting the right pelletizing equipment for your recycling operation.<\/p>\n

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Quick Specs<\/h3>\n
\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\nValue<\/th>\n<\/tr>\n<\/thead>\n
Pelletizer Types<\/td>\nStrand, Underwater (UWP), Water Ring<\/td>\n<\/tr>\n
Throughput Range<\/td>\n50\u20133,000+ kg\/hr<\/td>\n<\/tr>\n
Pellet Shapes<\/td>\nCylindrical (strand) \/ Spherical (die-face)<\/td>\n<\/tr>\n
Compatible Polymers<\/td>\nPE, PP, PET, PS, ABS, PA, PC & compounds<\/td>\n<\/tr>\n
Die Plate Hole Diameter<\/td>\n2.0\u20136.0 mm (standard)<\/td>\n<\/tr>\n
Residual Moisture<\/td>\n<0.05% (UWP) to <1% (strand)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

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What Is a Plastic Pelletizer?<\/h2>\n

\"What<\/p>\n

A plastic pelletizer is an equipment that takes thermoplastic polymer or shredded plastic waste as input and produces small, uniform plastic pellets (usually 2-5 mm diameter). These small balls of plastic, also called nurdles or granules, then flow into downstream technology such as an injection or blow molding machine or a film die.<\/p>\n

Regardless of cutting method, the pelletizing process stays the same. Typically, raw plastics are fed through an extruder and then thermo-mechanically processed to they are melted and then transported through a screen change. Next, the melted polymer is conveyed through a die with several to several hundred holes, then cut into pellet-sized pieces, dried, cooled and then transported through a conveyor system to a pellet silo. Each step impacts pellet quality in terms of shape, size and moisture content.<\/p>\n

Pelletizing is relevant to recycling since the U.S. EPA<\/a> states that up to 50% of the energy needed to produce virgin resin can be saved by recycling plastics. When recycled plastic scrap is pelletized according to standards such as the APR guidelines<\/a> (which stipulate moisture content below 0.5% as outlined in ASTM D6980) the resulting pellets replace virgin material in many applications. Typically, energy consumption for PP recycling is in the range of 1 to 4 kWh\/kg at design throughput, acknowledging that motor size and efficiency; as well as the calorific value of the waste, influence the results.<\/p>\n

For plastics processors looking to purchase recycled plastics it is the degree of pellet formation that allows or prevents conventional processing without modification. Pellets that break apart in hoppers or exhibit inconsistent characteristics in the final product can be blamed on plastic pelletizer machines<\/a> that were not specified in terms of throughput, pellet size, residual moisture and bulk density.<\/p>\n

How Does a Plastic Pelletizer Turn Waste into Pellets?<\/h3>\n

Six steps comprise this process. 1) Sorted plastic scrap is fed into the extruder hopper by a metering device and shredded. 2) The extruder barrel is heated to above the polymer melt point while the screw produces pressure. 3) The polymer is pushed through a screen changer that removes all debris and foreign particles. 4) The material is then forced through a die plate with block holes drilled into the face to produce strands. 5) a pelletizer system located at the die face or several feet downstream slices the strands into pellets. 6) The pellets are cooled or quenched in a water bath, a water ring, or a pressurized chamber. They are then conveyed pneumatically to the drying unit in a centrifugal dryer. From there, dried pellets are conveyed pneumatically to storage.<\/p>\n

The complete transformation is 3-45 seconds depending on the system type.<\/p>\n

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Strand vs Underwater vs Water Ring: Three Pelletizing Systems Compared<\/h2>\n

\"Strand<\/p>\n

All three main pelletizing techniques do the same basic job\u2014carving the hot polymer into pellets\u2014but their location and method of cutting varies, and this variation influences everything from pellet shape and moisture content to capital costs and operator time required.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n
Feature<\/th>\nStrand<\/th>\nUnderwater (UWP)<\/th>\nWater Ring<\/th>\n<\/tr>\n<\/thead>\n
Throughput<\/strong><\/td>\n100\u20132,000 kg\/hr<\/td>\n500\u20133,000+ kg\/hr<\/td>\n200\u20131,500 kg\/hr<\/td>\n<\/tr>\n
Pellet Shape<\/strong><\/td>\nCylindrical<\/td>\nSpherical<\/td>\nLenticular<\/td>\n<\/tr>\n
Best Materials<\/strong><\/td>\nPET, PA, PP, filled compounds (up to 90% fill)<\/td>\nAll polymers<\/td>\nPE (LDPE, LLDPE, HDPE), PP, PC, PS<\/td>\n<\/tr>\n
Cooling<\/strong><\/td>\nWater bath + air knife<\/td>\nPressurized water chamber<\/td>\nWater ring + centrifuge<\/td>\n<\/tr>\n
Residual Moisture<\/strong><\/td>\n<1%<\/td>\n<0.05%<\/td>\n<0.5%<\/td>\n<\/tr>\n
Relative Cost<\/strong><\/td>\n$$ (lowest entry)<\/td>\n$$$$ (highest)<\/td>\n$$$ (mid-range)<\/td>\n<\/tr>\n
Operator Involvement<\/strong><\/td>\nHigh (conventional) \/ Low (ASP)<\/td>\nLow (automated)<\/td>\nLow<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Strand pelletizing\u2014this is the oldest and most familiar form of pelletization. A die-plate forms continuous rolls of molten resin which are coiled through the water bath, an air knife dries the surface, then the strands enter the strand cutter into which rotating blades cut the strands into cylindrical pellets. Filled compounds process more easily than with die-face technology because the strands are solid before being cut.<\/p>\n

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\u2714 Strand Advantages<\/strong><\/p>\n