When designing the PLE series planetary reducer, determining the matching motor power is not simply "looking at the power pairing", but a systematic process that requires comprehensive calculation and verification. The core is to ensure that the reducer can withstand the load under actual working conditions, not just match the nominal power of the motor.
The following are the specific steps to determine the motor power and matching reducer:
1. Clarify application requirements and load characteristics
First, you need to fully understand the operating conditions of your equipment, which is the basis for all calculations.
Load type: Is it a constant torque load (such as a conveyor belt, a hoist), a constant power load (such as a machine tool spindle), or a variable torque load (such as a fan, water pump)? Is the load subject to impact (such as a stamping machine) or does it require frequent starts and stops?
Working hours: Does the equipment run 24 hours a day or 8 hours a day? Different working systems directly affect the life of the reducer and the required service factor.
Installation environment: Is the environment humid, dusty or corrosive? This determines whether a special protection class (such as IP65) or material (such as stainless steel) is required.
2. Calculate core parameters: torque and speed ratio
This is the most critical step in Selection. Torque matching is the "life and death line" of Selection.
Determine the reduction ratio (i):
Reduction ratio = motor rated speed ÷ required output speed of the equipment.
For example, if the motor speed is 3000 rpm and the device requires an output of 100 rpm, the reduction ratio i = 3000 / 100 = 30.
Calculate required torque (T):
Core formula: T = 9550 × P / n
T: Torque, unit Newton·meter (N·m)
P: Power, unit kilowatt (kW)
n: rotation speed, unit revolution/minute (rpm)
Calculate the actual required torque: What you need to calculate is the actual required torque at the equipment end (reducer output end). This includes the torque required to overcome friction, gravity, and accelerate the load.
Application safety factor: The calculated torque value must be multiplied by a safety factor (usually 1.5~2) to deal with starting, emergency stop or unexpected impact.
Required rated torque = calculated torque × safety factor
3. Match motor and reducer specifications
After the required torque and speed ratio are clear, specific matching can be made.
Torque check: Make sure the rated torque of the reducer is ≥ the required rated torque. This is the most important principle and cannot be inferred from motor power alone.
Power matching reference: On the premise that the torque meets the requirements, you can refer to the conventional correspondence between motor power and reducer model for preliminary screening. For example:
0.2kW - 0.4kW motor → 60 frame reducer
0.75kW motor → 90 frame reducer
1kW - 2kW motor → 120 frame reducer
Physical size matching: The installation interface of the motor and reducer must be checked to ensure correct installation.
Motor flange: Measure the motor flange diameter (such as 60, 80, 90, 120, etc.).
Motor shaft diameter: Measure the diameter of the motor output shaft.
4. Consider precision and special requirements
Select appropriate reducer parameters based on the accuracy requirements of the application.
Backlash: This is a key indicator that affects positioning accuracy. For high-precision equipment such as robots and CNC machine tools, low backlash models (such as ≤5 arc minutes) should be selected. The higher the accuracy requirements, the higher the cost.
Efficiency: The efficiency of planetary reducers is usually above 95%. High efficiency means less energy loss and heat generation.
