Radial growth test is conducted for quantifying diametrical or radial growth of high RPM rotating parts. The forces on rotating parts grow alarmingly fast as rotational speed increases in any high speed rotating equipments. This can lead to substantial diametrical growth, which must be taken into consideration during the design, particularly, if touching a nearby stationary component is possible. It is a recent test done for a high-speed motor manufacturer. This test helps the customer's engineers to balance the flux density, manufacturing tolerances and material selections to optimize the motor/stator air gap.