Softfoot

Soft foot is a condition where you have uneven level of feet. This cause distortion on the machine frame as you tight or loosen the bolt. Effect of soft soft foot could be damaging for an equipment or at least decrease it’s operating life. Softfoot or casing distortion will cause several problems like :

1. Internal misalignment : Casing distortion will cause misalignment between the internal bearings. As the machine frame distorted due to softfoot, the bearing move relative to each other and when this relative movement exceeds bearing tolerance it going to deflect the shaft . Every time the shaft turn there will be back-and-forth bending moment, after a period of time, the shaft may develop fatigue crack and fail.

2. Distorted Bearings : As the machine distorted, the shaft bearings are also distorted. The effect of this distortion, the bearing will have two load zones 180 ^o apart. Softfoot is one of the major causes of outer race distortion in properly installed bearing.

Softfoot problem on a motor can be identified by the appearance of spectrum on 2x lf. This is caused by uneven air gap between rotor and stator due to frame distortion.