In the reducer Selection, the service factor (Service Factor, often recorded as SF, KA or fs) is the safety margin to deal with unforeseen factors such as starting shock, load fluctuation, calculation error and harsh environment. The theoretical calculation torque must not be directly used when Selection, it must be multiplied by a service factor greater than 1 to determine the final Selection torque (Selection torque = theoretical output torque × service factor).
For heavy loads and impact loads, the selection of service factor mainly depends on load characteristics, working system, equipment importance and operating environment. The following are specific selection guidelines and key parameters:
1. Reference range for selecting service factor
The service factor needs to be matched according to the actual load type and operating conditions of the equipment:
Smooth load (Type A): such as fans, water pumps, light conveyor belts, etc. that rotate at a constant speed, with uniform load and no impact. The service factor usually takes 1.0 - 1.2.
Moderate impact load (Type B): Such as mixers (materials may be uneven), elevators, winches, packaging machines, etc., with intermittent action or slight impact. The service factor is usually 1.2 - 1.5.
Heavy loads and severe impact loads (Type C): Such as crushers, stamping machines, excavators, heavy cranes, etc., face huge instantaneous torque and fatigue tests. The service factor must be 1.5 - 2.0 or even higher (some extreme working conditions require more than 2.5).
2. Key factors affecting the increase in service coefficient
After determining the basic service coefficient, it is necessary to conduct an upward adjustment assessment based on the following working conditions:
Working system and start-stop frequency: Continuous operation of the equipment (S1 working system) requires a higher service coefficient than intermittent operation; if the number of starts and stops per hour is frequent, the impact will be aggravated, and the coefficient needs to be increased appropriately.
Importance of equipment and maintenance conditions: For key equipment, core production lines, or situations where routine maintenance is difficult and repair costs are extremely high, the service factor needs to be increased to ensure lifespan.
Environmental conditions: If the equipment is in a high temperature, high dust, humid or corrosive environment, the heat dissipation becomes poor or the wear and tear increases, the service factor needs to be increased accordingly.
3. Key parameters of heavy load and impact load Selection
In addition to the service coefficient, when facing heavy load and impact conditions, the following core parameters must also be strictly checked:
Peak torque (overload torque) check: The reducer must not only meet the rated torque, but the instantaneous maximum torque that its structure can withstand (peak torque, usually 2-3 times the rated value) must ≥ the maximum peak torque that may occur in the application (including starting torque and extreme impact torque). If the starting torque converted to the output shaft exceeds the maximum allowable torque of the reducer, a larger model must be selected.
Moment of inertia matching: During frequent start and stop operations, a huge impact torque will be generated instantly. The ratio of the peripheral moment of inertia on the drive shaft to the motor"s moment of inertia needs to be calculated (fs = Je/Jm). If the impact load is too large or the calculated inertia ratio is greater than 10, it will easily cause damage to the reducer. You need to contact a technician for professional evaluation or select reinforced bearings.
