For identifiable glass-filled thermoplastic sprues, runners or other in-house scrap, choose a granulator around the material and its contact points—not a knife specification alone. Resin grade, filler type and percentage, part geometry and wall thickness, material temperature, and feeding pattern all affect what the machine must handle. A thin runner fed steadily is a different duty from a thick part arriving in batches, even when both use the same resin family.
Compare the complete wear configuration
Follow the material from entry into the cutting chamber to discharge. The knives do the cutting, but the chamber, rotor contact surfaces and, on a screened machine, the screen can also see abrasive material. Ask which surfaces have wear protection, what that protection consists of for the proposed configuration, and which parts can be replaced when worn. A special knife alone does not describe the rest of the machine.
| Contact area | Configuration and replacement scope |
|---|---|
| Knives and cutting edges | Identify the proposed knife configuration and which knives can be replaced; compare maintenance and replacement criteria for the intended material. |
| Cutting chamber surfaces | Identify the surfaces protected against wear and whether liners or other affected parts are replaceable. |
| Rotor contact surfaces | Identify the protected areas and which worn components can be repaired or replaced. |
| Screen, if fitted | Identify the screen specification and replacement method, including access for inspection and cleaning. |
These are comparison points, not a standard list of parts fitted to every machine. Check the wear parts and maintenance provisions included for each proposed model before comparing service work. The rotor and knife guide explains the cutting components in more detail.
Separate speed, screen design and wear protection
Low speed, screenless operation and wear-resistant construction describe different things. A low-speed machine is not automatically the best choice for every filled material, and a screened machine is not automatically unsuitable. Compare each design against the size and shape of the scrap, required feeding pattern and output. The choice between screenless and screened granulators also affects how the machine produces and controls its output.
For context, Rapid names a PowerTECH configuration for filled and abrasive materials in its 150 series. WITTMANN describes glass-fibre applications for its low-speed, screenless S-Max primus. These are examples of specific manufacturers' approaches; their features do not establish the configuration or suitability of another machine.
Use a trial to observe the job, then track wear over time
A short material trial can show how the supplied scrap feeds and what output is produced under the conditions used. Record the material, feed pattern and operating conditions alongside the result. It cannot establish long-term knife life or consumable cost. To compare wear over a longer period, keep records for the same material and configuration, including quantity processed, maintenance and the criteria used to replace parts.
RHONG's centralized granulator page is a starting point for discussing material and configuration. Contact us with the resin grade, filler percentage, largest scrap dimensions and feeding pattern so the application can be discussed against a specific configuration.