How to judge whether the thermal expansion gap of FAF87-32r/pm-7.5KW reducer is appropriate

To determine whether the thermal expansion gap of the FAF87 reducer is appropriate, the core is to measure the actual gap value of the key matching pair in the cold and hot states, and compare it with the design specification or empirical value. The following are the specific steps:

1. Core measurement methods

‌Static measurement‌: After stopping the machine for cooling, use a feeler gauge or dial indicator to measure the initial clearance of key parts such as gear backlash and bearing clearance.

‌Dynamic monitoring‌: Run the equipment to thermal equilibrium (oil temperature is stable), use an infrared thermometer to monitor the temperature of key points, and use a laser alignment instrument or vibration sensor to monitor the axial movement.

‌Thermal expansion calculation‌: Calculate the theoretical gap change based on the linear expansion coefficient of the material (such as steel about 12×10⁻⁶/℃) and the temperature difference, and compare it with the actual measured value.

2. Key inspection parts

‌Gear meshing backlash‌: Measured with the lead wire method or feeler gauge, the hot state gap should be slightly smaller than the cold state (usually reduced by 0.01-0.05mm).

‌Bearing clearance‌: Measure the axial/radial clearance between the bearing inner ring and the shaft, and the outer ring and the seat hole. The thermal clearance should be maintained within the manufacturer's recommended range (such as group C3).

‌Shaft system alignment‌: Use a laser alignment instrument to detect the axial/radial displacement in the hot state to ensure that the deviation is ≤0.1mm/m.

‌Seal clearance‌: Check the end clearance of the mechanical seal or labyrinth seal to avoid leakage caused by overheating.

3. Judgment criteria

‌Qualification standard‌: The change in thermal clearance is within ±10% of the theoretical calculation value, and the clearance in key parts (such as gears and bearings) is still within the allowable range.

‌Risk Warning‌: If the thermal gap approaches zero or exceeds the upper limit, the preload force needs to be adjusted or components replaced.

4. Operation suggestions

‌Measurement timing‌: The equipment should be operated continuously for more than 2 hours and the temperature should be stabilized.

‌Tool preparation‌: feeler gauge, dial indicator, infrared thermometer, laser alignment instrument, etc.

‌Record comparison‌: Record cold/hot state data and compare it with the equipment manual or historical data.