Fasteners are a critical component of the precision shaft alignment process, yet the importance of fasteners is many times overlooked. If bolting is not selected, assembled, and torqued correctly, it can make the precision shaft alignment process less accurate, more difficult to achieve, and potentially harmful to the machines.
While there are always unusual circumstances, normally machines are bolted together using this process. Whenever you are unsure, please consult your machine designer or engineering department.
BOLT – a fastener used in conjunction with a mating threaded nut or plate. It is used to apply force to two or more components to attach firmly, and to prevent unwanted movement. It should go through the top of the motor foot.
FLAT WASHER – provides a surface against which the head of the bolt, and the face of the washer contact. A flat washer increases the loading area of the bolt and nut, prevents damage to from the machine foot or base caused by turning the fastener, and spans the hole thru which the fastener goes.
LOCK WASHER – a helical spring or toothed washer which serves to retard movement due to inadequately tightened fasteners.
NUT – a block, with a threaded hole, normally hexagonal, into which a bolt is threaded for the purpose of clamping force.
Establishing and maintaining a proper tightening sequence is critical to precise alignment. Bolts should be tightened in a crisscross pattern, like a pipe flange or head gasket.
You should also tighten in several passes, adding more torque with each pass. This will help minimize any unintended movement of the machine while tightening.