When it comes to plastic recycling, size matters more than you might think. I’ve seen firsthand how those tiny granules can make or break the entire recycling process. Too big, and they won’t wash properly; too small, and you might as well be throwing money—and plastic—down the drain. The question of “how small is too small” isn’t just academic—it’s a practical dilemma that recyclers face daily.
The Goldilocks Zone of Plastic Granules
The sweet spot for plastic granules typically falls between 20mm to 100mm, with 30mm being that magic number where efficiency peaks. Our testing at the facility showed something fascinating: granules around 30mm size increase washing efficiency by a whopping 40% compared to their 100mm counterparts. Why? Simple physics—smaller pieces mean more surface area, which means better degreasing and contaminant removal. But here’s where it gets tricky—when pieces drop below 20mm, we start seeing material losses of 15–20% during washing, not to mention the nightmare of increased wastewater pollution.
Ever wonder what happens to those ultra-fine particles? They slip through screens, clog filters, and—here’s the kicker—can actually contaminate batches of otherwise good recycled material. It’s frustrating when you realize that some of these losses could’ve been avoided with better pre-shredding control.
When Smaller Isn’t Better
You’d think that shredding plastic down to near powder would be the ultimate goal—after all, finer material should mean more thorough recycling, right? Wrong. Here’s what actually happens:
- Energy waste: It takes significantly more power to shred material below 10mm—sometimes up to 30% more energy input for diminishing returns
- Quality degradation: Over-shredding can mechanically damage the polymer chains, reducing the material’s structural integrity
- Downstream chaos: Those tiny particles wreak havoc on extrusion equipment, with screens clogging 30% faster than normal
I remember one batch where we accidentally shredded PET flakes down to about 5mm—the entire production line turned into a nightmare of jams and contamination alerts. Lesson learned the hard way!
The Contaminant Factor
Here’s something most people don’t consider—the smaller the granule size, the harder it becomes to remove contaminants. Metal fragments or mineral deposits that would normally be sorted out at larger sizes suddenly become nearly indistinguishable from the plastic itself when everything’s ground down too fine. Our quality control team spends up to 50% more time dealing with contaminated batches when granule sizes dip below 15mm.
The irony? Some recyclers chase smaller sizes thinking it’ll lead to higher purity, when in reality they’re often making their contamination problems worse. It’s one of those counterintuitive realities of plastic recycling that you only learn through years of hands-on experience.
Finding the Balance
After a decade in this business, I’ve come to view granule sizing as more art than science. The “perfect” size changes depending on:
- Plastic type (PET behaves differently than LDPE)
- Downstream processes (mechanical recycling vs. pyrolysis)
- Contamination levels
- Equipment capabilities
Our SG3000 shredders address this challenge with customizable screen sizes and intelligent feed control. The ability to adjust output between 20–100mm with ±2mm tolerance has been a game-changer—finally giving operators precise control over this critical variable. It’s not just about avoiding being “too small”—it’s about hitting that moving target of “just right” for each unique recycling scenario.
At the end of the day, understanding granule sizing is about recognizing that in recycling—as in life—extremes rarely work. Neither the biggest nor smallest sizes are ideal. The true mastery lies in finding that perfect middle ground where efficiency, quality, and practicality intersect.
