Granulator Blades Manufacturer: Granulator Knives & Shredder Blades
As a granulator blades manufacturer we machine rotary knives, bed knives and complete knife sets from SKD11, D2 and HSS, ground to the cutting clearance your rotor actually runs. As a granulator blades supplier we ship single replacement knives or a fully matched set, and we quote both, because half our customers are changing one chipped blade and half are rebuilding a rotor.
1. What we make
Rotary and bed knives
The working pair on a granulator. Both are dimensioned together, because the cutting clearance is set by the difference between them — not by either blade on its own.
Granulator knife →Recycling shredder blades
Heavy-section blades for plastic, rubber and PET crushers, supplied as a set with the fixed and rotary knives sized to the same machine class.
Shredder blade set →Double shaft shredder blades
Thick disc-type blades for twin-shaft shredders — tyres, bulky waste, cable and industrial scrap — made to your drawing or sample.
Twin shaft blades →2. Granulator knife sets by machine size
If your machine is one of the common PC-series granulators, the set composition below is what we ship most often. The counts matter as much as the sizes: a rotor that takes nine rotary knives will not run correctly on eight.
| Machine size | Fixed (bed) knife | Rotary knife |
|---|---|---|
| PC300 | 298 × 80 × 17 mm · 2 pcs | 99.5 × 80 × 17 mm · 9 pcs |
| PC360 | 358 × 110 × 15 mm · 2 pcs | 60 × 70 × 15 mm · 18 pcs |
| PC400 | 398 × 80 × 17 mm · 2 pcs | 99.5 × 80 × 17 mm · 12 pcs |
| PC470 | 234 × 90 × 20 mm · 2 pcs | 94 × 85 × 17 mm · 15 pcs |
| PC500 | 498 × 85 × 17 mm · 2 pcs | 99.5 × 85 × 17 mm · 15 pcs |
| PC600 | 298 × 80 × 17 mm · 4 pcs | 99.5 × 80 × 17 mm · 18 pcs |
Set compositions from the recycling shredder blade range. Non-standard sizes are made to drawing.
Machines outside this list are the normal case rather than the exception. Send the rotor drawing or a worn knife with the bolt pattern visible, and we will work from the mounting dimensions instead of the machine name.
3. Material and hardness
| Material | Hardness | Where it is the right choice |
|---|---|---|
| SKD11 | HRC 58–62 | The default for plastic and rubber granulators — high wear resistance with enough toughness to survive occasional metal contamination |
| D2 | HRC 58–62 | Abrasive streams: glass-filled plastic, cable with filler, PET with grit. Holds an edge longer, less forgiving of impact |
| HSS | HRC 60–62 on request | Where the blade runs hot or the material is harder than expected; better hot hardness than cold-work die steel |
| Custom alloy | to your specification | Mixed waste streams where neither wear resistance nor toughness alone solves the problem |
Grades listed on the granulator knife page. Hardness is specified in writing on every order and verified by sampling the finished batch before it ships.
Wear in a granulator is rarely uniform. Rotary knives lose their edge along the cutting face, bed knives wear across the whole edge, and both can look acceptable on the machine while cutting badly. If you are seeing more fines, more noise, or a rising motor load, the blades are usually the cause before anything mechanical is.
4. What decides whether a set fits your rotor
Four dimensions decide fit, and only one of them is the blade length everyone quotes first.
- Cutting circle and hook angle. On rotor knives the mounting face is angled relative to the cutting edge. A knife ground to the wrong hook angle will sit proud or recessed, and the clearance to the bed knife will be wrong across the whole rotor.
- Bolt pattern and counterbore. Hole spacing, hole diameter and counterbore depth. A pattern that is 0.5 mm out will not clamp.
- Blade thickness. Sets the clearance against the bed knife together with the rotor adjustment. Thicker is not stronger here — it is a different machine setting.
- Number of cutting edges. A four-edge reversible knife is a different commercial proposition from a single-edge knife: it costs more per blade and less per tonne, and it only pays if the rotor geometry supports indexing.
5. Regrind, index or replace
Three options, and the right one depends on how much material is left above the bolt.
| Option | When it makes sense | What to expect |
|---|---|---|
| Index the blade | Four-edge reversible knives with a clean unused edge | Cheapest per hour of running time — no machining, no downtime beyond the swap |
| Regrind | Enough body left that the mounting face is still true after grinding | Lower cost than new, but the blade gets thinner each cycle; check the clearance afterwards |
| Replace the set | Chips, cracks, or a body worn close to the bolt counterbore | A matched set restores the original clearance and stops the rotor chasing a bad edge |
We would rather tell you to regrind than sell you a set you do not need. Send photographs of the cutting edge and we will say which of the three applies.
6. How the blades are made
Blanks are cut and machined on CNC, then ground to the cutting geometry and the mounting faces. Hardness is specified in writing on the order and verified by sampling the finished batch — we test the batch rather than trusting the incoming certificate alone. Dimensions are checked against the drawing before packing, and every set is packed as a set so the knives that were ground together stay together.
Because we grind to drawing rather than to a catalogue, a custom set usually needs no tooling investment. The two things that do slow an order down are an incomplete bolt pattern on the drawing and a hardness specification that contradicts the material — both are worth ten minutes of checking before you send it.
7. Related pages
- Industrial blade size chart — granulator set dimensions alongside every other blade family we make.
- Recycling shredder blades — the product category, with all grades and set options.
- All product series — the other nine blade families, from doctor blades to oscillating knives.
Frequently asked questions
Yes. Single knives are the more common order. What we will flag is that a new knife next to a worn one changes the clearance between them, so if the rest of the set is close to the end of its life, replacing one knife can cost more in cut quality than it saves.
How do I measure a granulator knife?Length, width and thickness at the mounting face, plus the bolt hole spacing measured centre to centre and the counterbore diameter and depth. Add the cutting edge angle or the hook angle if the drawing has it. A photo of the mounting face with a ruler across it is worth more than a paragraph of description.
Do you make four-edge reversible knives?Yes, where the rotor geometry supports indexing. They cost more per blade and less per hour of running, which is why they suit high-throughput lines and are usually unnecessary on small machines.
What hardness should I specify?For plastic and rubber granulators, HRC 58–62 in SKD11 or D2 covers most cases. Go higher only if the wear is abrasive rather than impact-driven; a harder blade chips sooner in a stream that contains metal. If you are unsure, tell us what you are grinding and we will recommend a grade.
Can you match a knife from a worn sample?Yes. Send the worn knife and we measure it, then send the reading back for you to confirm before we quote. That step catches the case where the worn blade is itself the wrong part — which happens more often than you would expect on older machines.
Send a rotor drawing or a worn knife
Tell us the machine, the material and what you are getting now per blade, and we will come back with the grade, the set composition and the price per set rather than per piece.
Request a granulator blade quote