Precision Twin Shaft Shredder Blades for Li-Ion Battery Recycling

Battery packs contain copper and aluminum current collector foils that are 8–20μm thick. When the shear gap between counter-rotating blades exceeds approximately 0.05mm, the foils deform plastically rather than shearing—folding and wrapping around the rotor, causing operational jams. In a nitrogen-purged environment, clearing a rotor jam requires complete shutdown of the inert gas system, evacuation, and manual removal—hours of downtime consuming significant N₂. Holding blade thickness parallelism to ±0.02mm guarantees a consistent minimum shear gap across the full rotor length, preventing foil wrap-arounds under normal operating conditions.

LiPF6, the most common lithium-ion electrolyte salt, reacts with trace atmospheric moisture to produce HF (hydrofluoric acid). In a cell breach event during pre-shredding, even a nitrogen atmosphere contains enough residual moisture for partial hydrolysis. Standard tool steel grades (D2, SKD11) corrode rapidly in HF—surface pitting initiates at grain boundaries within 200–500 hours, degrading edge geometry and reducing shear efficiency. Sureay applies specialized anti-corrosion surface treatments to extend service intervals significantly beyond standard tool steels in battery recycling lines.

Twin-shaft (dual-shaft) shredders are standard for EV battery pack primary size reduction because the counter-rotating, low-speed high-torque design subjects cells to controlled shear rather than impact. This controlled failure mode reduces acute thermal events compared to high-speed single-shaft impactors. Precision twin-shaft blades with controlled shear clearances are therefore the mechanical first-stage standard, followed by further downstream processing.

Battery pre-shredders from specialist manufacturers (Erdwich, Hosokawa, Metso, and Andritz battery recycling lines) use proprietary rotor shaft profiles more precisely toleranced than general industrial shredders. Wire-EDM splined and hexagonal bores to ±0.01mm are required for zero-play rotor mounting—any rotational backlash at operating speed causes consistent shear gap variation and foil jam risk. We manufacture bore profiles to custom shaft drawings; please provide the rotor shaft profile drawing for exact bore specification.