Plastic granulators fall into four main families: powerful (standard) granulators for general scrap, low-speed beside-the-press granulators for immediate runner recycling at the injection machine, medium-low-speed granulators balancing the two, and large-diameter heavy-duty granulators for bulky or thick-walled parts. This guide defines each type and shows which one fits which job.

The four main types at a glance

1. Powerful (standard) granulators

Powerful granulators are the workhorses: medium-to-large cutting chambers, higher motor power, and a fast rotor that handles rejected molded parts, sprues collected in batches, thin wall products, and general clean plastic scrap across several machines. They produce high throughput but generate more noise and fines than low-speed models, so they are usually placed in a separate granulation area, often with a soundproof enclosure and dust extraction.

• Best for: factories collecting mixed scrap centrally and needing high kg/h
• Strengths: versatile, fast, accepts a wide range of part sizes
• Watch out for: noise, fines, and blade wear if fed heavy lumps beyond spec

2. Low-speed beside-the-press granulators

Low-speed granulators operate with a slow, high-torque cutting action directly beside the injection-molding machine. A robot or conveyor drops the sprue and runner in immediately after demolding; the clean regrind can return to the same machine at once. Because cutting is slow, they create far less noise, dust, and material degradation, and energy use is low.

• Best for: single-machine, single-resin runner recycling with no contamination
• Strengths: quiet, low fines, low energy, immediate closed-loop reuse
• Watch out for: not designed for thick lumps, purgings, or large parts

3. Medium-low speed granulators

Medium-low-speed models sit between low-speed beside-the-press units and full powerful granulators. They granulate runners and small-to-medium rejected parts with less noise and fewer fines than a high-speed machine, while accepting occasional larger pieces. They are a practical compromise for shops that want beside-the-press convenience but process bigger runners or heavier parts than a compact low-speed model can take.

• Best for: larger injection machines and heavier runner systems
• Strengths: balanced cut, lower noise, bigger chamber than low-speed units
• Watch out for: still not a substitute for a heavy-duty lump granulator

4. Large-hollow / large-diameter heavy-duty granulators

Heavy-duty granulators are built with an extra-wide feed opening, thick steel construction, heavy flywheel rotors, and high-torque drives. They swallow large hollow products — drums, bins, crates, pallets, automotive and appliance components — plus thick purging lumps that would jam a standard machine. Many are sold with soundproof enclosures, hydraulic chamber opening, and conveyor feeding.

• Best for: blow-molding, logistics products, thick purgings, bulky rejects
• Strengths: very high torque, oversized feed, continuous industrial duty
• Watch out for: higher investment and footprint; needs stable power supply

Specialized granulators worth knowing

• Film granulators: steep-angle rotors and special chambers prevent thin film and fiber from wrapping the rotor
• Pipe/profile granulators: elongated feed openings accept long pipes and extruded profiles
• Inline sprue granulators: mini low-speed units mounted directly under a robot or press for instant reuse
• Bottle granulators: often paired with a compactor or pre-treatment line for PET bottles

How the types compare on noise, fines, and cost

Frequently Asked Questions

Q: Which type of plastic granulator is best for injection molding?

A: Most injection molders use a low-speed or medium-low-speed beside-the-press granulator for immediate, contamination-free runner recycling, and keep a central powerful or heavy-duty granulator for rejected parts, lumps, and purgings.

Q: Does low-speed granulation produce better regrind quality?

A: Generally yes. The slower cutting action generates less heat, dust, and fines, so the regrind is cleaner and more uniform — which is why low-speed machines are preferred for closed-loop recycling beside the press.

Q: Can one granulator handle every kind of plastic scrap?

A: No. Thin film wraps unsuitable rotors, thick lumps need high torque, and large hollow parts need a wide feed opening. Matching the machine type to the scrap shape prevents stalls, blade damage, and downtime.

Q: What does 'beside-the-press' mean?

A: It means the granulator is installed next to an injection-molding machine and fed directly with the sprue and runner as parts are demolded, allowing the same-resin regrind to be reused immediately without transport or contamination.

Q: Are all these types available with different blades?

A: Yes. Reputable manufacturers such as Lesintor offer SKD or 9CrSi blades across the range and customize knife configuration, screen size, and voltage to the application.

The right 'type' is decided by scrap shape, not by brand or horsepower. Profile the largest and the most frequent waste on your floor — then choose the slowest, quietest machine that can still handle the hardest piece.

About Lesintor

Suzhou Lesintor Import and Export Co., Ltd. (Lesintor) is a Chinese manufacturer with 20 years of experience in injection-molding auxiliary equipment. Its granulator range covers powerful granulators, low-speed beside-the-press granulators, medium-low-speed models, and large-hollow / large-diameter heavy-duty granulators, with SKD or 9CrSi blades customized to the application. Every machine carries a one-year warranty and is built to ISO and CE standards.

Website: www.lesintormachine.com   |   Email: sales1@lesintor.net   |   WhatsApp: +1 628 488 4101