Fixture keeps machines dynamically aligned

Edited by the Engineeringtalk editorial team Oct 11, 2002

Dynamic changes to rotating machinery in transition from an offline to running condition need careful consideration as there is no such thing as "identical" machines with identical dynamic movements.

Dynamic changes to rotating machinery in transition from an offline to running condition need careful consideration as there is no such thing as "identical" machines with identical dynamic movements.

One can never ignore the possibility of horizontal movement, assuming growth will be symmetrical and only accounting for the thermal effects.

Most shaft alignment is carried out offline.

However, machine conditions change from the time they are offline to running under normal operating conditions.

Some of these changes are due to process forces (fluid pressures, airflow etc).

The most notable of these changes is the change in the temperature of the machine bearings and supports.

Dynamic changes are difficult to calculate.

Two "identical" machines may show drastically different alignment changes from offline to running.

Great care must be taken when calculating the changes in the alignment condition of machines.

Just because two machines appear identical and serve the same function does not ensure they will exhibit the same operational characteristics.

Several methods have been used to measure the changes in the shaft alignment of two or more machines.

Although widely used, "hot aligning machines" only measure changes in shaft alignment due solely to changes in the machine temperature.

Discharge pressure, shaft torque, multiple machines operating in parallel, electrical loading of a generator etc, can also play an important role in the change of the alignment condition from offline to running.

The changes will mostly be seen in the horizontal plane, but could also affect the vertical alignment.

A machine that operates exposed to large changes in temperature could exhibit extreme changes in its shaft alignment as the temperature changes.

Coupled machines need to be set to cold alignment targets that will reflect the actual changes in the shaft alignment.

This will lead to lower vibration levels, increased mean time between failures, decreased maintenance costs, and increased production.

Fixturlaser's extensive research into the problems of dynamic movement has resulted in a revolutionary new alignment method.

The Fixturlaser OL2R offline-to-running fixture combined with a Fixturlaser shaft alignment system makes it possible to measure dynamic movements on machines from hot to cold or vice versa.

Changes in machinery alignment are mirrored by changes in the alignment of the OL2R brackets.

By measuring and documenting the initial position of the brackets the actual online changes in the alignment values can be measured when the machine is online under normal operating conditions.

Alignment costs are small compared to production loss, should critical machinery fail.

Poor alignment is one of the leading contributors to premature rotating machinery failure, often as a result of too little attention being paid to dynamic movements.

Fixturlaser has shown, through extensive tests, that in addition to cold alignments, the actual dynamic movements of machinery need to be considered when aligning.