Complete selection, calibration, and common selection of Bonfiglioli C-A-F industrial gear units

Complete selection, calibration, and common selection of Bonfiglioli C-A-F industrial gear units

Product series positioning and basic parameter boundaries

Bonfiglioli C-A-F modular gear unit is the main product of industrial universal hard tooth surface gear transmission. The three series have clear structural positioning, and the first step in selection is to confirm whether the structural form matches the overall layout of Bonfigliol.

C series: inline helical gear reducer, input-output coaxial arrangement, machine base C05~C100, output torque 45-12000Nm; various variants of foot P, flange F, UNIBOX universal box U; 2-4 level deceleration, suitable for parallel input and output conditions such as assembly lines, fans, pumps, etc.

A series: oblique cone spiral bevel gear right angle reducer, input and output 90 ° orthogonal, machine base A05-A90, suitable for space limited scenarios where the motor side is arranged vertically with the actuator, such as conveyor drives, lifting mechanisms, and packaging machinery.

F series: Hollow shaft suspension reducer, hollow output shaft directly sleeved on the driven spindle, relying on torque arm to counteract the reaction torque, typical applications include belt conveyors and screw conveyors.

Basic environmental boundary (mineral oil version): working environment temperature -10 ℃~+40 ℃; Storage -10 ℃~+50 ℃; Maximum continuous surface temperature of the shell+100 ℃; The maximum oil temperature of lubricating oil is+95 ℃; It is not recommended to operate continuously at 80-95 ℃ for a long time. Synthetic lubricating oil should be preferred for high-temperature conditions, and the fluororubber seal Bonfigliol should be replaced at the same time.

Many projects skip environmental boundary verification in the early stage of selection, and operate in tropical workshops, outdoor exposure, and enclosed cabinets. If the ambient temperature exceeds 40 ℃, it will directly reduce the thermal power capacity, resulting in abnormal high temperatures, premature aging of oil seals, and oil leakage.

Core selection input list: Complete working condition collection

According to the official sample A7 selection collection form, complete working condition parameters must be collected before formal selection, and any missing item will bring hidden risks.

Load: Maximum/minimum output speed n2, required torque Tr2; Maximum input speed n1; Load moment of inertia Jc;

Shaft load: actual radial load Rc1/Rc2 on input and output shafts; The distance between the load and the shoulder is X1/X2; Axial thrust Ac1/Ac2, thrust direction (push/pull);

Work system: daily operating hours; Hourly start stop frequency Zr; working system S1/S2/S3, cycle duration I; load impact level (uniform K1/moderate impact K2/strong impact K3);

Environmental conditions: ambient temperature, altitude, whether the container is sealed;

Mechanical configuration: installation positions B3/B5/V1/V3, etc; Motor form IEC/NEMA; Solid shaft input HS or motor flange input; Are there brakes, backstops, or special anti-corrosion coatings.

Common engineering misconceptions: Only collecting the motor nameplate power, ignoring the actual torque, cantilever load, and start stop frequency on the output side, and directly selecting the reducer base based on the motor power, resulting in a smaller base selection and premature failure of bearings and gears in the later stage.

Correct determination of service coefficient (f_s ) (the most critical step in selection)

The service coefficient (f_s ) represents the safety margin caused by working condition impact, start stop frequency, and daily operating hours, and is not equal to the motor service coefficient. It directly determines the fatigue life of gears and bearings.

3.1 Determination of Load Impact Level K

According to the mass acceleration coefficient K, the ratio of load inertia to motor inertia is: (K=Jc/Jm )

K ≤ 0.25 → K1: Uniform load (centrifugal fan, centrifugal pump)

0.25 ＜ K ≤ 3 → K2: moderate impact (ordinary conveyor, mixer)

3 ＜ K ≤ 10 → K3: Strong impact load (crusher, bucket elevator, reciprocating equipment)

K＞10， It is necessary to contact the manufacturer for technical evaluation, and it is not allowed to directly apply sample charts.

Based on the sample chart, read the service coefficient (f_s ) according to the daily working hours, hourly startup frequency Zr, and K level. The sample is accompanied by a large number of industry reference tables: recommended service coefficients for industries such as mixers, fans, crushers, cranes, hoists, and papermaking equipment. Lifting equipment belongs to high-risk loads, and the service coefficient value is significantly higher than that of ordinary industrial equipment.

Selection calculation formula: Calculate the torque (T_ {c2}=T_ {r2} × f_s ), and select the rated output torque of the reducer (T_ {n2} ≥ T_ {c2} ).

High frequency error: directly take (f_s=1.0 ); Choosing a service factor that is too small for impact conditions such as lifting and crushing; Ignore the lifting effect of high start stop frequency per hour on (f_s ); Confuse the motor service coefficient with the gearbox service coefficient. According to AGMA experience, a slight decrease in service coefficient will result in an exponential decay of gear fatigue life.

Double verification of mechanical capacity and thermal capacity (easily overlooked)

The vast majority of selection only verifies the mechanical torque capacity, and the lack of thermal capacity verification is the primary cause of overheating and lubricating oil degradation in the continuous S1 working system reducer.

4.1 Mechanical Capacity Selection

There are two input forms:

IEC motor flange input reducer: (P_ {n1} ≥ P_ {r1} × f_s ); Safety factor (S=P_ {n1}/P_1 ≥ f_s );

Solid input shaft HS reducer: Based on the output torque, it meets the requirement that the rated output torque is greater than the calculated torque (T_ {n2} ≥ T_ {c2} ).

Instantaneous peak torque: The sample specifies that the short-term peak load is not allowed to exceed 200% (T {n2} ). Switching high and low speeds of a dual speed motor will generate high switching impact torque. It is recommended to use a two-phase electrical delay strategy to suppress the impact, otherwise a torque limiter needs to be added.

4.2 Thermal Capacity Verification (P_t)

Thermal capacity (P_t ) refers to the maximum power that can be transmitted by the gearbox S1 during continuous operation at an ambient temperature of 20 ℃, ensuring that the lubricating oil does not deteriorate rapidly. If the ambient temperature is higher than 20 ℃ and the intermittent working system is used, the thermal correction coefficient (f_t ) should be used for correction. The verification formula is:

(P_{r1} ≤ P_t × f_t)

Important reminder: If the deceleration is greater than level 2 and the speed ratio i is greater than 45, the general heat capacity is greater than the mechanical capacity, and the risk of hot air is relatively low; Under conditions of 2-level high speed ratio and high-speed input, thermal capacity often becomes a bottleneck for selection. If the heat capacity is insufficient, the solution is: ① enlarge the machine base; ② Replace synthetic lubricating oil; ③ Add external cooling fans; ④ Reduce the continuous operating power.

Engineering site phenomenon: The torque of the machine base fully meets the working conditions, but the oil temperature exceeds 95 ℃ during long-term continuous operation, the lubricating oil carbonizes, and the oil seal quickly fails. The root cause is that the thermal capacity has not been verified.

Verification of radial load and axial thrust load of cantilever (the primary cause of bearing failure)

The C-A-F sample clearly specifies the allowable cantilever loads (R_ {n1}, R_ {n2} ) and allowable axial thrusts (A_ {n1}, A_ {n2} ) for the input and output shafts. Pulleys, sprockets, and gear drives can cause significant radial loads and are the most common sources of bearing damage.

5.1 Overhung Load

Calculation formula:

(R_c= frac {2 · T · Km} {d} ) (Km ) is the transmission element coefficient: chain Kr=1.0; Gear Kr=1.25; V-belt Kr=1.5; Flat belt Kr=2.0; D represents the pitch diameter of the sprocket/belt pulley.

Sample allowable radial load reference condition: the load application point is located at the midpoint of the axis extension; The load is offset outward away from the shaft shoulder, and the allowable radial load must be reduced by a correction factor (a/(b+x) ). The further the load is, the lower the allowable value. The values in the sample table cannot be directly applied.

5.2 Axial thrust load

When there are both rated radial load conditions, axial thrust is allowed:

(A_{n1}=0.2 × R_{n1}； If there is no radial load and pure axial thrust, the allowable value can be increased to 0.5 times the allowable radial load; When the axial thrust value is large, or when both radial and axial loads are applied simultaneously, the bearing configuration must be evaluated by the manufacturer.

High frequency selection error: Directly copying the allowable radial load from the sample table, the actual installation position of the sprocket is far away from the shaft shoulder without any reduction; Neglecting the axial thrust caused by the screw and bevel gear ultimately leads to bearing overheating, abnormal noise, and early pitting failure.

Key points for selection and matching of installation posture, lubrication, and storage

Many selections are completed, but the installation position parameters are written incorrectly when ordering, which can directly cause lubrication failure. This is a key control point in the ordering stage, Bonfigliol.

Installation position: The entire C-A-F series supports multiple postures such as B3, B5, V1, V3, B6, B7, etc; The oil level height is completely determined by the installation posture; Ordering must specify the installation location, and the factory will add the corresponding amount of oil according to the ordering posture; When transporting from the factory, replace the ventilation plug with a transport closure plug. It is necessary to replace the ventilation plug during on-site operation, otherwise pressure accumulation may cause oil leakage.

Lubricant selection: Mineral oil, PAG synthetic oil, PAO synthetic oil correspond to different temperature ranges; Mineral oil and synthetic oil are strictly prohibited from mixing and blending. C05-C41, A05-A41, F10-F41 factory pre filled lubricating oil; C51/A50/F51 and larger machine bases do not require oil injection at the factory, but require on-site filling; Some versions offer long-life maintenance free PAG oil.

Long term storage requirements: Cannot be stored outdoors in high humidity; Apply rust inhibitor on the contact surface of the workpiece; If stored for more than 6 months, it is recommended to lubricate and replace the vent plug with a new plug; Do not use strong solvents to clean the surface of the oil seal when using it again, as it will damage the rubber seal.

Additional constraints for ATEX explosion-proof versions: The installation posture of explosion-proof models cannot be modified arbitrarily; Synthetic oil, fluororubber seals, and vent plugs with intrusion protection valves must be used, and ordinary C-A-F parameters cannot be directly applied.

Complete verification checklist after selection (item by item verification is required after selection)

Complete the initial selection of the machine base speed ratio, but cannot directly output the selection result. The following verification needs to be completed item by item, which is also a checklist for engineers to avoid later failures:

✅  Confirm the service coefficient (f_s ), confirm the K level, start stop frequency, and daily operating duration; Lifting equipment with increased margin;

✅  Mechanical strength verification: (T_ {n2} ≥ T_ {r2} × f_s ); Instantaneous peak value ≤ 200% (T {n2} );

✅  Thermal capacity verification: (P_ {r1} ≤ P_t × f_t ), adjust the ambient temperature and working system;

✅  Radial cantilever load: Calculate the actual (R_c ), reduce it according to the load position, and make it smaller than the corrected (R_n );

✅  Axial thrust verification: Confirm that the actual Ac is within the allowable range of the sample, and submit the heavy load combination load to the manufacturer for evaluation;

✅  Reduction ratio confirmation: Check the precise speed ratio to avoid output speed deviation caused by only looking at approximate speed ratios;

✅  Installation posture confirmation, the installation position of the ordered model is completely consistent with the overall machine drawing;

✅  Motor matching: Confirm the geometric compatibility of the motor flange, and also confirm the maximum allowable power input of the reducer, not just the flange size;

✅  Environmental temperature and altitude decrease; Confirmation of lubricating oil model; Seal material matching working conditions (ordinary nitrile rubber/fluororubber);

✅  Special accessory confirmation: backstop AL/AR, anti-corrosion coating C3/C4, dual oil seal, low backlash RB option, etc.

Summary of Typical Selection Errors and Fault Phenomena in 8 Industrial Projects

Error description, on-site fault manifestation, solution

Only select based on motor power, ignoring the actual output torque and service coefficient, gear pitting, tooth breakage, abnormal noise during operation, short-term damage, recalculate the output torque, correctly select (f_s ), upgrade the machine base

S1 runs continuously, only checking the mechanical capacity, skipping the thermal capacity check. If the oil temperature remains above 95 ℃, the lubricating oil turns black, and the oil seal leaks oil, calculate the thermal capacity. Increase the machine base or use synthetic oil and cooling fan

The load position of the sprocket/belt pulley is far away from the shoulder of the shaft, and the radial load is allowed to be directly applied to the sample without reducing the high temperature and abnormal noise of the bearing. The shaft seal is damaged and leaks oil, and the bearing is corroded in advance. The load reduction is based on the load distance, and it is necessary to increase the base or sprocket diameter to reduce the radial force

Incorrect ordering and installation posture, mismatched oil level, insufficient low-speed lubrication, gear wear; The high-speed oil level is too high, stirring heats up and leaks oil. Modify the order model, refill the oil according to the actual posture, and replace the vent plug

High impact, frequent start stop conditions, incorrect judgment of K level The value of (f_s ) is biased towards small gear fatigue, periodic impact noise, and a lifespan far below design expectations. Re evaluate the inertia ratio K, improve the service factor, and it is necessary to add a torque limiter

Neglecting the axial thrust load (screw, agitator), bearing overheating on one side, axial displacement, and seal damage, calculate the axial thrust. It is necessary to contact the manufacturer for a bearing reinforcement plan