{"id":2191,"date":"2026-09-29T05:48:45","date_gmt":"2026-09-29T09:48:45","guid":{"rendered":"https:\/\/slecotech.com\/?p=2191"},"modified":"2026-09-29T06:06:01","modified_gmt":"2026-09-29T10:06:01","slug":"purge-lumps-shredder-how-big-a-lump-one-machine-can-take-without-pre-cutting","status":"publish","type":"post","link":"https:\/\/slecotech.com\/es\/purge-lumps-shredder-how-big-a-lump-one-machine-can-take-without-pre-cutting\/","title":{"rendered":"Trituradora de grumos: \u00bfQu\u00e9 tama\u00f1o de grumo puede procesar una m\u00e1quina sin necesidad de precortar?"},"content":{"rendered":"
\n

Somebody sends me a photo most weeks. A purge lump sitting on a concrete floor, a boot or a drink can next to it for scale, and one line underneath: “can we feed this as-is?”<\/p>\n

That’s the right question to ask, and it’s the one nobody answers clearly. Brochures print throughput numbers and motor power. They rarely print what actually decides whether your Monday morning goes smoothly \u2014 how big a single block the machine will bite.<\/p>\n

So let’s answer it properly. Here is where the real limit sits, what the feed openings actually measure on our machines, and the exact point where you have to reach for a saw first.<\/p>\n

Most of the time you don’t. One machine takes your lumps whole. But the cases where it doesn’t are worth knowing before you sign anything, because “we’ll just cut the big ones by hand” is a decision that costs you a wage every single week.<\/p>\n

“Purge Lump” covers three different things<\/h2>\n

First, the word is doing too much work. When a buyer says purge lumps, they usually mean one of three, and they behave differently in a shredder.<\/p>\n

Color-change and grade-change purge.<\/strong> The classic one. You push the next material through until the color runs clean, and what comes out is a rope or a slab that cools into a hard irregular block. Usually PP, PE, ABS, sometimes PC. Fist-sized up to a shoe box. Call it 2 to 8 kg. Soft when it’s still warm, genuinely hard once it’s cooled overnight.<\/p>\n

Die and head purge.<\/strong> The material you drag out of the die head or screen pack during a teardown. Denser, often darker, sometimes partly degraded. 5 to 15 kg, and much harder than a color-change block. This is the stuff that tells you whether your rotor and cutters were specified honestly.<\/p>\n

Startup and shutdown blocks.<\/strong> The big ones. A full purge-out at the end of a run, sometimes dumped into a drum or a mold box and left to set. 300 to 400 mm on the long side is common. Over 20 kg isn’t unusual. Occasionally there’s a bolt, a heater band fragment, or a piece of tooling in there.<\/p>\n

I ask which one you have because the answer changes the machine. A shop feeding fist-sized color-change blocks all day is an easy spec. A shop with 25 kg die-head blocks every Friday is a different conversation.<\/p>\n

The limit isn’t the hopper. It’s the bite.<\/h2>\n

This is where people get it wrong. They look at the feed opening, see a number, and assume anything smaller than that number goes in fine.<\/p>\n

The hopper only decides whether the block fits<\/strong>. What decides whether it breaks<\/strong> is whether the rotor can get purchase on it.<\/p>\n

Here’s the mechanism on a single shaft shredder. A hydraulic ram pushes the block against a slow, high-torque rotor. The rotor knives hook the surface and drag it across a fixed counter knife, tearing a layer off with each pass. Pieces leave when they’re small enough to fall through the screen.<\/p>\n

So two things matter:<\/p>\n