SKD11, SKH-2, and TCT Blades: What's the Difference?
Why Blade Material Choice Matters
When buying a granulator, blade material is the specification most commonly overlooked. Equipment supplier quotations typically list only "standard blades" without specifying the material. After delivery, operators discover blade wear is far faster than expected and consumable costs far exceed the budget.
Blade material choice directly determines your sharpening interval and long-term consumable costs. Plants processing different materials may require completely different blade materials.
SKD11 Tool Steel
SKD11 is the most common standard blade material for granulators — the default configuration for most equipment shipped from the factory.
Basic characteristics: SKD11 is a high-carbon, high-chromium cold-work tool steel, typically Rockwell hardness HRC 55–58. High hardness with moderate toughness — can withstand a certain degree of impact without catastrophic fracture across the full blade.
The greatest advantage is re-grindability. Each sharpening removes a small amount of metal and restores edge sharpness; a single blade can be sharpened multiple times before reaching its replacement limit. Overall use cost is relatively low. Sharpening service providers are widely available.
Suitable materials: PP, PE, ABS, PS — general plastic waste and moderate-hardness industrial scrap. These materials do not cause severe blade wear; SKD11 service life is adequate and cost-efficiency is best.
Not suitable for: glass-fiber-reinforced engineering plastics, carbon-fiber plastics, mineral-filled plastics. These materials' abrasiveness causes extremely rapid SKD11 wear — sharpening intervals compress to unacceptable frequency.
SKH-2 High-Speed Steel
SKH-2 is a high-speed tool steel (HSS), also called "white steel," containing tungsten, chromium, vanadium, and other alloying elements. Both heat resistance and wear resistance are better than SKD11.
Basic characteristics: SKH-2 typically achieves HRC 58–63 — slightly above SKD11. More importantly, its heat resistance means it maintains better hardness at elevated temperatures — meaningful for granulator blades under continuous high-load operation, as blades are less prone to softening from friction-generated heat.
Wear resistance better than SKD11: when processing the same material, SKH-2 service life is typically 30–50% longer than SKD11, with correspondingly longer sharpening intervals.
Toughness between SKD11 and TCT: SKH-2 is somewhat more brittle than SKD11, with a higher probability of chipping when encountering metal contamination — but far less so than TCT carbide. For operations where waste sources are not fully controlled and occasional metal contamination occurs, SKH-2 is safer than TCT.
Sharpening method identical to SKD11: standard sharpening equipment can grind it; no special equipment required; sharpening cost and difficulty similar to SKD11 — a clear advantage over TCT.
Suitable materials: slightly harder engineering plastics, ABS/PC alloys, or applications requiring long continuous operation. Also suitable as a transition material for operations that cannot fully commit to TCT due to occasional contamination risk.
TCT (Tungsten Carbide-Tipped)
TCT (Tungsten Carbide Tipped) — the main component is tungsten carbide sintered with cobalt — has far greater hardness than SKD11 or SKH-2.
Basic characteristics: TCT typically achieves HRA 88–92 Rockwell (A-scale). Wear resistance is several to tens of times better than SKD11, with service life against highly abrasive materials that other blade materials cannot approach.
The greatest advantage is extreme wear resistance: against glass-fiber, carbon-fiber, and mineral-filled materials, TCT service life is dramatically longer than the other two options. This can substantially reduce sharpening and replacement frequency — long-term consumable costs may actually be lower than SKD11.
Main disadvantage — high brittleness: TCT toughness is significantly lower than SKD11 and SKH-2. When encountering metal contamination or strong impact, it shatters far more readily than the other two. Plants using TCT blades must be especially rigorous about contamination screening before feeding — a single metal contaminant can cause far more severe blade damage than it would with SKD11.
Sharpening is difficult and expensive: TCT hardness is extreme — standard sharpening equipment cannot grind it; diamond wheel equipment is required. Some providers do not offer TCT sharpening at all; replacing with new blades may be the more practical approach — but this makes per-use costs higher. Initial cost is also high: TCT unit price is typically 5–10 times SKD11. Evaluate cost per kilogram of waste processed — not unit price alone — to make a meaningful comparison. Against high-abrasion materials, TCT's longer service life often makes the total economics more favorable.
Suitable materials: glass-fiber-reinforced engineering plastics (GF content above 30%), carbon-fiber-reinforced plastics, mineral-filled plastics, and other highly abrasive waste.
Quick Comparison
SKD11: hardness HRC 55–58; toughness medium; wear resistance standard; heat resistance standard; re-grindability high; initial cost low; suitable for general plastics.
SKH-2: hardness HRC 58–63; toughness medium-low; wear resistance good; heat resistance good; re-grindability high; initial cost medium; suitable for harder engineering plastics and long continuous runs.
TCT: hardness HRA 88–92 (extreme); toughness low; wear resistance excellent; heat resistance good; re-grindability low (requires special equipment); initial cost high; suitable for highly abrasive materials (glass-fiber, carbon-fiber, mineral-filled).
Related articles: How to Sharpen Granulator Blades — sharpening method differences by blade material; How to Granulate Glass-Fiber-Reinforced Engineering Plastics — complete wear management guidance for abrasive materials.