Saving Money and Improving Efficiency

In a sense, this whole section is about one, and only one topic: MONEY. If alignment can be improved, machinery failure rate drops dramatically. Equipment failures are a major maintenance expense and have numerous incidental or associated costs. In fact, the cost of parts and labor to repair the machine can be one of the smaller costs. Lost production, contractual penalties, consequential damages, and liability for injury can all be much more expensive than the repair itself.

If half of the alignments in your plant are done with a straight edge and the other half with dial indicators, our experience tells us that the average misalignment in the plant will be about 15 mils (offset and angular misalignment, where the angular misalignment is expressed in mils/10"). This misalignment will create an average power loss of 0.842% (please note that this is a very conservative figure: there is a high likelihood of this value being significantly higher.)

For machines operating 365 days a year, 24 hours a day, at an average cost of energy of $0.06 per Kilowatt hour, the Total Cost of Lost Power (TCLP) for a small industrial plant running up to 150 small to medium-sized machines (average of 35 HP) can be determined to be:

TCLP = 150 machines × 35 HP/machine × 0.7457 Kw/HP × 365 days/year × 24 hours/day × 0.00842 × $0.06/KwHour = $17,325.70 per year.

With precision alignment it is possible to achieve an average misalignment of just 2 mils. This misalignment creates an average power loss of 0.041%. Thus, the new TCLP will be:

TCLP = 150 machines × 35 HP/machine × 0.7457 Kw/HP × 365 days/year × 24 hours/day × 0.00041 × $0.06/KwHour = $843.65 per year.

Therefore, the reduction in Cost of Power is: $17,325.70 – 843.65 = $16,482.04.

These savings easily pay for a new laser alignment system in one year, without taking into consideration all the other attendant benefits from the reduction in misalignment, such as reduced vibration resulting in improved product quality, greater manufacturing output efficiency, and reduced wear and tear on the machines with the consequential reduction in labor, repair and spare parts expenses. Add to this the reduction in unscheduled downtime and the savings become almost incalculable.

For machinery installation, only the rotating shaft centerlines of different machines are aligned. Not the feet, not the coupling, not the shaft surfaces, not the machine housings, not the bearings; only the rotating shaft centerlines. It is important to understand that alignment refers to the positions of two centerlines of rotation or two rotational axes. Note that the shaft’s rotational centerline may be different than its machined centerline.

Shaft alignment means: Positioning two or more machines so that their rotational centerlines are colinear at the coupling point under operating conditions. Colinear means two lines that are positioned as if they were one line. Colinear as used in alignment means two or more centerlines of rotation with no offset or angularity between them.

The phrase "coupling point" in the definition of shaft alignment is an acknowledgement that vibration due to misalignment originates at the point of power transmission, the coupling. It does not mean that the couplings are being aligned. The shafts are being aligned, and the coupling center is just the measuring point.

"At operating conditions" is an acknowledgement that machines often move after start-up due to wear, thermal growth, dynamic load shifts, or support structure shifts.

Besides the above considerations, the term shaft alignment also implies that the bearings and shafts are free from preloads. In properly installed equipment, there are no forces or strains on the bearings and shafts, except those the designers intended. If the machine is installed with the frame distorted because of uneven or imperfect base plates, bent feet, pipe stresses, or whatever, then machine life will be shortened, often significantly.

The only way to determine rotational centerlines is to rotate the equipment. There is no series of measurements that do not involve turning the shafts between readings that can be used to find the rotational centerline.

Any system that takes so-called alignment measurements without turning BOTH shafts is aligning surfaces, not centerlines of rotation. The results of any alignment efforts where one or both shafts are not turned are highly dependent upon surface quality, rotor eccentricity, shaft straightness, and other surface defects. In short: "If you do not turn the shafts, you are not doing shaft alignment."