How to Measure the Dynamic Balance of a Crankshaft
Aug 14, 2025| 
Test Procedure
Step 1: Preparation & Installation
(1) Clean the crankshaft surface to remove oil, burrs, or debris that could affect measurement accuracy.
(2) Remove accessories such as flywheel and pulley unless required for testing.
(3) Mount the crankshaft main journals onto the balancing machine supports, ensuring concentricity.
(4) Attach the drive belt or coupling as per the equipment's requirement.
Step 2: Initial Measurement
(1)
Start the balancing machine and rotate the crankshaft at the specified speed (commonly 300–600 rpm).
(2)
Sensors collect vibration data, and the system calculates the unbalance amount (unit: g·cm or g·mm) and angular position for each balancing plane (usually the front and rear ends).
Step 3: Correcting the Imbalance
Common correction methods include:
Weight Removal
drilling, milling, or grinding material at the specified position
Weight Addition
adding balance weights, welding, or attaching screws at the required position
Step 4: Re-test
Run the crankshaft again to measure the residual unbalance.
If the unbalance is within the tolerance (e.g., ±1–3 g·cm), the crankshaft passes.
If outside tolerance, repeat the correction process.
Regularly calibrate the balancing machine to maintain measurement accuracy.
Avoid strong vibrations or wind interference during testing.
Ensure the main journals are undamaged to maintain stable support.
For multi-cylinder crankshafts, ensure both planes (or multiple planes) are balanced.
