Lenze BFK458-25 Electromagnetic Spring Brake – 400 N·m Fail-Safe Braking | BFK458 Series
Engineering Background
The Lenze BFK458 series represents the industry benchmark for spring-applied, electromagnetically released brakes in servo-driven and variable-speed drive applications. Engineered in Germany to DIN/IEC standards, the BFK458-25 delivers a rated holding torque of 400 N·m at 180 VDC, making it the preferred choice for high-inertia axes, vertical load holding, and safety-critical E-stop functions across heavy industrial machinery.
Product Positioning
The BFK458-25 is designed for procurement engineers specifying fail-safe braking on servo motors, gearboxes, and direct-drive systems where power-off braking is a functional safety requirement. It integrates directly with Lenze i700, 8400, and 9400 servo inverter families, as well as third-party drives via standard 180 VDC brake supply modules.
Complete Technical Specifications
| Parameter | Value |
|---|---|
| Part Number / SKU | BFK458-25 (400 N·m) 180VDC |
| Brand / Manufacturer | Lenze SE (Germany) |
| Series | BFK458 |
| Brake Type | Spring-Applied, Electromagnetically Released (Fail-Safe) |
| Rated Holding Torque | 400 N·m |
| Rated Supply Voltage | 180 VDC |
| Operating Mode | Power-off braking (spring engages on de-energization) |
| Engagement Time | Typically < 50 ms (load dependent) |
| Release Time | Typically < 100 ms at rated voltage |
| Insulation Class | Class F (155 °C) |
| Protection Rating | IP54 (standard); IP65 available on request |
| Ambient Temperature | -20 °C to +40 °C |
| Mounting Interface | Flange-mount, IEC motor frame compatible |
| Weight | 33 kg (approx.) |
| Country of Origin | Germany |
| Compliance | CE, UL, RoHS |
Proven Application Environments
- Vertical axis holding – Gantry cranes, Z-axis CNC, robotic arms requiring gravity load retention on power loss
- Servo motor braking – Direct coupling to Lenze MCS/MCA servo motors and third-party IEC frame motors
- Winding & unwinding machines – Tension control and emergency stop on paper, film, and textile lines
- Conveyor & material handling – Inclined conveyors, pallet lifters, and automated storage systems
- Packaging machinery – High-cycle indexing stations requiring rapid, repeatable braking
- Wind energy & pitch control – Blade pitch locking under grid fault conditions
Engineering Advantages
- True fail-safe architecture – Spring engagement guarantees braking without electrical power; compliant with IEC 60204-1 safety stop categories
- High torque density – 400 N·m in a compact flange envelope minimizes motor shaft extension and system footprint
- Long service life – Sintered friction lining rated for >1,000,000 switching cycles under rated load
- Low maintenance – Wear indicator and manual release lever standard; no lubrication required
- Wide drive compatibility – 180 VDC coil voltage matches standard Lenze and third-party brake rectifier outputs directly
- Thermal stability – Class F insulation sustains performance in continuous-duty high-ambient environments
System Architecture & Signal Flow
The BFK458-25 operates on a normally-engaged principle:
- Power OFF / E-Stop → Coil de-energized → Spring pack clamps friction disc → Shaft locked at 400 N·m
- Power ON / Run command → 180 VDC applied to coil → Electromagnetic force compresses spring → Friction disc released → Shaft free to rotate
- Brake supply → Typically sourced from Lenze brake rectifier module (e.g., EBR series) or integrated drive brake output; coil current monitored for wear diagnostics
- Feedback → Optional microswitch for brake-released confirmation signal to PLC/safety relay
Sourcing & Quality Verification
- All units sourced directly from Lenze-authorized distribution channels or verified surplus with full traceability documentation
- Each unit inspected for: original Lenze labeling, date code, coil resistance within ±5% of datasheet, and mechanical engagement function
- Certificate of Conformity (CoC) and original Lenze packaging provided where available
- Batch photos and inspection reports available upon request prior to order confirmation
- Konmask.com maintains a no-counterfeit policy — all products rejected if authentication cannot be verified
Procurement Process
- Inquiry – Submit your BOM or part number to support@konmask.com or via the product page
- Stock confirmation – We confirm availability, lead time, and unit price within 24 business hours
- Quotation – Formal quotation issued with HS code 8505.20 for customs clearance
- Payment – T/T, PayPal, or trade-term options (EXW/FOB Xiamen)
- Shipping – DHL / FedEx express (3–5 days) or sea freight for bulk orders; export documentation included
- After-sales – 12-month warranty against manufacturing defects; technical support from Konmask engineering team
Technical FAQ
Q: Can the BFK458-25 be used with a 24 VDC brake supply?
A: No. The BFK458-25 coil is rated for 180 VDC. A 24 VDC supply will not generate sufficient electromagnetic force to release the spring. Use the correct Lenze brake rectifier or a 180 VDC DC power supply.
Q: Is manual release possible during maintenance?
A: Yes. The BFK458-25 includes a standard manual release lever allowing the brake to be held open mechanically without electrical power — essential for axis jogging during commissioning.
Q: What is the expected service interval?
A: Under rated load and normal duty cycles, the friction lining is rated for >1,000,000 actuations. Lenze recommends inspection at 500,000 cycles or annually, whichever comes first.
Q: Can this brake be retrofitted to non-Lenze motors?
A: Yes, provided the motor shaft diameter and flange dimensions match the BFK458-25 mounting interface. Consult the Lenze BFK458 dimensional drawing (available on request) and verify IEC frame compatibility.
Q: What certifications does the BFK458-25 carry?
A: CE marking (Machinery Directive 2006/42/EC), UL recognition, and RoHS compliance. Suitable for use in SIL 2 / PLd safety functions when integrated with an appropriate safety relay.
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