Bonfiglioli BXN/MXN Motor Installation and Brake Maintenance Complete Guide



Complete guide for installation and brake maintenance of Bonfiglioli BXN/MXN series motors

In industrial transmission systems, the motor is the core power source, and its installation quality and maintenance level directly determine the reliability of the entire production line. Bonfiglioli's BXN, BX, BE, BN and compact MXN, MX, ME, M series three-phase asynchronous motors are widely used in various harsh working conditions due to their high energy efficiency (IE2/IE3) and rich braking options (FD DC braking, FA AC braking). However, even the highest quality motors can result in unplanned shutdowns or even safety accidents if there are omissions in installation wiring, brake adjustments, or regular maintenance.

This article will be based on Bonfiglioli's official "Installation, Operation, and Maintenance Manual" to provide on-site engineers with a full process technical guide from receiving acceptance to daily maintenance. The focus will be on analyzing key operations such as air gap adjustment, rectifier wiring, and insulation testing unique to brake motors to ensure safe and efficient operation of the equipment throughout its lifecycle.

Safety first: Essential checks before installation

Before coming into contact with any motor, it is necessary to confirm that the operator is qualified and familiar with safety regulations. The manual clearly states that the motor has live or rotating parts during operation, and removing the protective cover, improper use, or inadequate maintenance may result in serious personal injury.

Identification of nameplate: Each motor has a nameplate, which includes the serial number and production year. When the serial number is 17 digits, the year is in the 3rd to 4th digits; At position 13, it is in positions 5-6. Before starting any installation, it is essential to verify whether the voltage, frequency, power, and braking parameters on the nameplate match the on-site power supply.

Transportation and storage: The motor is usually fixed on a wooden pallet and can be transported by forklift. For motors with base numbers BXN100/MXN30 and above, eyebolts are provided, but they are only suitable for lifting the motor itself and are strictly prohibited from being used to lift the entire gear motor or assembly. When stored for more than 60 days, rust inhibitor (such as Mobilarma 248) should be applied to the flange and shaft extension surfaces; If it exceeds 6 months, the rotor should be rotated once a month to prevent the bearing grease from solidifying.

Mechanical installation: Details determine lifespan

2.1 Axial extension treatment and corrosion prevention

When the new motor leaves the factory, the shaft extension is coated with a rust proof protective layer. Before installation, it needs to be cleaned with a suitable solvent, but do not let the solvent come into contact with the oil seal lip, otherwise it will cause the sealing ring to swell and fail. After cleaning, apply anti seize agent (such as Loctite 767) on the shaft to effectively prevent micro corrosion of the shaft and its mating parts, and also provide convenience for future disassembly. The manual recommends removing the motor, cleaning the shaft extension, and reapplying anti seize compound every 6-12 months.

2.2 Installation Space and Heat Dissipation

The motor adopts IC411 self cooling method (with built-in fan), and it is necessary to ensure that there is sufficient distance between the fan cover and the surrounding walls or obstacles to ensure free circulation of cooling air. When installing outdoors, it is necessary to install a sunshade to prevent direct sunlight and rainwater from entering. For brake motors with manual release levers, the release lever should be unscrewed and properly stored after installation to prevent accidental misoperation that may cause the brake to release.

2.3 Insulation resistance test

After the first start-up or long-term parking, a 500V DC megohmmeter must be used to measure the insulation resistance of the winding to ground. The insulation value of the new winding at 25 ℃ should be greater than 10M Ω. If it is lower than this value, it indicates that the winding is damp and needs to be dried in an oven, otherwise forced power transmission may cause inter turn short circuits.

Electrical wiring: the core points of brake wiring

Bonfiglioli motors offer multiple wiring schemes, especially for motors with DC brakes (FD type), the correctness of wiring directly affects the braking response time and safety.

3.1 Standard Single Speed Motor Wiring

The terminal box is usually pre connected with a rectifier (for FD braking). Connect the main circuit according to the Δ/Y connection indicated on the nameplate (230/400V or 400/690V). The grounding terminal must be reliably grounded.

3.2 Four typical control schemes for FD brakes

According to whether independent power supply or rapid braking is required, the manual provides four types of wiring diagrams (A~D):

Option A (standard): The brake coil is powered by the motor terminal, and the braking action is delayed when the AC side is disconnected. It is suitable for soft start/stop situations.

Option B: The brake coil adopts an independent power supply (SA option), and the braking time does not depend on the motor time constant, which is suitable for applications that require precise control of the braking timing.

Option C: Simultaneously disconnect the AC and DC lines to achieve rapid braking (using NBR/SBR rectifiers).

Option D: Independent power supply and simultaneous disconnection of AC and DC to achieve the fastest braking response.

Important reminder: Due to the inductive load of the brake coil, the control contacts must be selected according to the use category of AC-3 (AC) or DC-13 (DC) that complies with IEC 60947-4-1, otherwise the contacts are prone to burning.

3.3 New Series FDD Brakes (for BXN/MXN)

The EVOX series motor adopts the FDD new brake, and its rectifier wiring is more complex, providing NR (standard performance) and SR (fast performance) rectifiers, and supporting multiple voltage combinations (WD1~WD12 configurations). The manual provides a detailed voltage/connection comparison table (such as WD1-50 applicable to 115/200/230/400V, etc.). For frequency converter power supply applications, the brake must use an independent power supply (SA) and ensure that the voltage is consistent with the motor nameplate.

3.4 Anti condensation heater (H1/NH1 options)

If the motor is equipped with an anti condensation heater, its power supply must be independent and must be cut off before the motor runs. This heater is used to prevent winding condensation during shutdown, especially suitable for humid environments.

3.5 Steering confirmation

When connected to the U-V-W terminal in phase sequence L1-L2-L3, it rotates clockwise when viewed from the drive end. Swap any two phases to reverse. For motors equipped with one-way anti reverse devices, the nameplate will clearly indicate the allowed direction and corresponding phase sequence, which must be strictly followed.

Start debugging: final check before loading

Before the first power on, complete the following checks one by one:

Confirm that all safety protection devices are installed in place.

No load power on, check if the rotation direction is consistent with the requirements.

Check if the independent fan (if any) is functioning properly.

Monitor the running sound to ensure no abnormal vibration or friction.

If equipped with a brake, repeatedly tap it several times to confirm that the brake can be properly engaged and released.

If there is excessive current, abnormal temperature rise, abnormal noise or severe vibration, immediately cut off the power and investigate the cause. Do not forcefully operate with load.

Daily maintenance and adjustment of brake air gap

The most critical maintenance item for the brake motor is the regular inspection and adjustment of the brake air gap (T). Excessive air gap can lead to increased braking noise, incomplete release, and in severe cases, a decrease in braking torque; If the air gap is too small, it may cause dragging and overheating.

5.1 FD brake air gap adjustment steps

Loosen the locking nut (ref.2).

Adjust the air gap to the minimum value specified in the table (e.g. Tmin=0.2mm, Tmax=0.5mm for FD02~FD53) by turning the hexagon socket bolt (ref.1) or nut (ref.3).

Secure the bolt and tighten the nut.

Check the empty stroke "X" of the manual release mechanism, which must be greater than the lower limit value in the table (such as X ≥ 0.8mm).

The thickness of the friction plate must always be greater than 1.5mm, otherwise the brake disc needs to be replaced.

5.2 FDD Brake Air Gap Adjustment (New Type)

Loosen the hexagonal socket bolt slightly (ref.1).

Use a wrench to rotate the socket bolt (ref.2) clockwise to increase the air gap and counterclockwise to decrease the air gap (about 1/6 turn to change by 0.15mm).

Adjust to Tmin (0.2 or 0.3mm) and tighten the bolt.

Also check the minimum thickness of X stroke and friction plate (see Table 1 and Table 2 in the manual).

5.3 Routine Maintenance Checklist

Check the operating current and temperature every month.

Clean the fan cover and motor surface every quarter to prevent dust blockage.

Check if the cable entry port and sealing ring are intact.

If there is a condensate drain hole (option), regularly unscrew the screw plug to drain the accumulated water.

Standard bearings require maintenance free grease lubrication, but it is recommended to check or replace the bearings every 3 years of operation.

Quick troubleshooting and spare parts management

When the brake shows slow response, abnormal noise, or insufficient braking force, first check the air gap and friction plate thickness, and then verify whether the rectifier input/output voltage is normal. For fast braking applications, it is essential to use SR series rectifiers to achieve strong excitation and fast shutdown.

Chapter 8 of the manual provides a detailed list of spare parts kits (kits), covering motor flanges, rotors, fans, bearings, brake discs, springs, rectifiers, etc. It is recommended that users pre stock commonly used vulnerable parts (such as brake discs, rectifiers, seals) according to the motor model to reduce downtime waiting time.

Scrapping and environmental disposal

When the motor is scrapped, it should be disassembled and classified according to the EU WEEE Directive (2012/19/EU) and local regulations. Iron, copper, aluminum, plastic, and electronic components should be recycled separately and not mixed with household waste.