Soft-Foot
Soft-foot is a condition when all the supporting members (feet) of a machine are not equally supporting the weight of the machine or piece of equipment, this condition is referred to as soft-foot. When the machine does not sit firmly on its feet, soft-foot is a major contributing factor of shaft misalignment. As a result it can stress the machine housing and in-turn distort the bearing bores to that of oval shape.
Soft Foot may be due to one or more of the following conditions:
- Improperly machined equipment support feet
- Dirt and foreign material under the machine's foundation
- The anchoring bolts may not have been properly torqued during the grouting phase
- A bad base-plate design
- Incorrect levelling procedures
- The vibration from the equipment may have loosened the hold down bolts
- Over time the grout may have deteriorated and started to crumble
- The foundation may have settled
- The sections of the equipment may have been poorly installed and assembled
- Depending upon the conditions perhaps the base or foot of the machine has corroded.
Ordinary & Angular Soft Foot
There are two types of soft-foot: Ordinary & Angular.
- Ordinary soft-foot is an even gap that occurs between one foot of the machine to the sole-plate or base-plate.
- Angular soft-foot is a irregular or angular gapping that exists between the foot of the machine to the base or sole-plate
What is consider to be a good foot to base fit?
Well a proper fit, would be that of a flatcontact, between the two surfaces. There should not be any form of gaping between the base-plate and the installed shim pack. Bearing this in mind though, the gap between the foot and shim pack should be less that 0.025mm (0.001").
