Electrical Protection: Breakdown voltage up to 3000V. Blocks stray currents to prevent electrical corrosion.
Competitive Pricing: Efficient sourcing channels allow us to offer more competitive pricing than the market average
Interchangeable: Compatible with SKF/FAG/NKE models for a perfect replacement.
Variety of Types: Both C3/C4 and brass retainers, stamped steel retainers, are available for selection.
TFL 6328M/C4VL2071 is a 100% equivalent and direct replacement for large-size insulated bearings from SKF/FAG/NKE in terms of mechanical dimensions (140x300x62mm), solid brass cage design (M), C4 clearance, and VL2071 inner-ring standards. All bearings undergo strict voltage resistance and insulation resistance testing before dispatch. Customers can achieve direct replacement without changing the original motor shaft or end-shields.
| SKF | FAG | NKE |
|---|---|---|
| 6328M/C4VL2071 | 6328-M-J20C-C4 | 6328-M-C3-SQ77E |
Meeting the extreme industrial demand that overlays a “140mm large bore, solid brass cage, C4 extra-large clearance, and bore ceramic coating” relies on a premium supply chain. Relying on a robust premium power transmission supply chain network and a strict quality control system, TFL provides high-quality products that deeply integrate advanced coating processes with precision mechanical standards. We not only provide high-reliability anti-erosion solutions rivaling top global brands but also offer professional technical support from our engineering team for selection and diagnostics. With rapid-response stock availability and No MOQ, TFL is dedicated to helping global clients eliminate lead-time risks on large specialized parts, achieving significant cost optimization.
Inner-Ring Insulation (VL2071) — High-bond alumina coating on the bore and side faces to isolate high-voltage stray currents directly at the source.
Heavy-Duty 63 Series Design — Dimensions 140 x 300 x 62 mm, built to withstand massive radial and shock loads (approx. 20.5 kg).
C4 Extra-Large Clearance — Absolutely critical for surviving extreme temperature gradients and massive heat transfer.
TFL 6328M/C4VL2071 is exclusively designed for VFD systems where the stator and housing have specialized connections, while concurrently facing extreme heavy-duty loads, extreme operating temperatures, severe vibrations, and VFD leakage currents. Typical applications encompass AC traction motors in heavy-haul railways requiring absolute stator grounding, main motors of metallurgy hot rolling mills requiring tight water-cooled fits, and massive mining ball mills utilizing split housings. Its solid brass cage provides unmatched mechanical impact rigidity, while the VL2071 inner-bore coating constructs a robust defense protecting the high-temperature shaft system from electrical erosion when housing assembly is restricted.
In AC traction motors for heavy-haul freight locomotives or high-speed trains by CRRC, to meet strict electromagnetic compatibility (EMC) and grounding specifications, the motor end-shield must maintain direct metallic conductive contact with the bearing’s outer ring. This absolutely prohibits the use of outer coatings. Due to the massive heat generated by high-torque startups and intense track shocks, the TFL 6328M/C4VL2071 employs an inner-bore insulation design, cutting off common-mode leakage currents at the shaft journal while utilizing the heavy 63 series cross-section and brass cage to resist impacts. Its C4 extra-large clearance reserves ample anti-seizure buffer for high thermal expansion, acting as the premier high-spec insulated solution for overhauls.
In VFD main drive motors (such as heavy-duty systems built by Siemens and ABB) for hot strip mills in steel plants, bearings are continuously exposed to radiant high temperatures, frequent overloads, and immense mechanical shocks from billet gripping. The bearing housing is equipped with a water-cooling jacket, requiring an extreme interference fit with the outer ring, preventing outer-ring coatings. TFL 6328M/C4VL2071’s inner-ring insulation design perfectly matches this heat-dissipation structure, isolating high-frequency shaft currents while ensuring excellent housing thermal conductivity. The solid brass cage resists severe load vibrations, and the C4 extra-large clearance absorbs dangerous differential thermal expansion when the shaft journal is extremely hot (up to 120°C - 150°C).
In the main drive systems of large mining ball mills or heavy crushers by Metso, the housing often adopts a split design to facilitate the lifting of large-shaft rotors. This structure demands absolute outer-ring conformance to the housing bore with micron-level tolerances, leaving no room for outer coated interference. TFL 6328M/C4VL2071 utilizes inner-ring insulation, isolating high-voltage VFD leakage currents directly at the rotor shaft without altering precision housing assembly. Its C4 clearance prevents seizure caused by continuous high-temp operations under heavy loads, and the brass cage combined with the 63 series heavy-duty structure ensures stable, continuous production under severe impacts from extremely hard ore.
*The brands and series mentioned are provided for industry illustration only. Final bearing selection should be confirmed through verification of dimensions, clearance class, insulation type, and operating conditions. For selection assistance or technical consultation, please contact the TFL engineering team for support.
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