Define the change before investigating
A finer-looking batch can reflect a change in particle distribution, but appearance alone does not tell you how much fines content has changed. Agree on a test sieve and report the fines as a mass proportion of a representative sample. Record how and where each sample was taken, and use the same method when comparing batches. Airborne dust at the machine and fines measured in a sample are different observations; one cannot substitute for the other.
Keep the material, feed and collection conditions with the sample record. Note the resin and scrap form, the screen fitted, the collection route and any changes since the earlier batch. If several conditions changed together, the comparison cannot identify which one caused the difference.
Use symptoms to direct inspection, not to diagnose
| Observation | Inspect or record | Conclusion not yet justified |
|---|---|---|
| Higher measured fines | Sampling method, material and feed conditions | The screen alone caused the change |
| Dusty or uneven output | Knife condition and knife gap against the machine manual | Blades are the only possible cause |
| Changed flow through screen | Screen condition and maintenance history | A smaller aperture will solve the problem |
| Dust around collection | Collection and conveying route as well as the cutting station | The sample fines proportion is known |
Worn knives or an incorrect knife gap can accompany poorer cutting and more fines. A worn or obstructed screen also deserves inspection. These are possibilities, not a diagnosis from a symptom: see Conair’s granulator maintenance guidance and Wittmann’s service tips. Follow the applicable machine manual for inspection and maintenance settings.
Before maintenance or cleaning, trained, authorized personnel should stop the machine, isolate the energy supplies, control stored energy and verify the safe state and stopped rotor under the model manual and factory isolation procedure. An emergency stop alone is not the isolation procedure.
Compare the result across the whole route
Record the condition found and the work completed, then compare representative output samples using the agreed sieve and mass calculation. Keep the material, feeding and collection conditions comparable and note any differences. Agree separately on the quality criteria for accepting the output; this comparison has no universal pass threshold.
A dust separation device may be considered in the collection route, but it does not repair worn knives or make an unsuitable resin acceptable. Likewise, screen aperture is only one part of the particle distribution. The screen size guide explains that distinction, while the capacity guide covers the conditions behind output figures.
For a new installation, review the general-purpose plastic granulator and send the material, sample method and collection requirements with your inquiry.