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How to: Laser Shaft Alignment

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Why Shaft Alignment Matters

Alignment in your machines is vital to the reliability of your operations. When two machines are misaligned, severe failure can occur causing unplanned downtime and loss of revenue. Some negative consequences are seal failure, bearing failure, energy loss from inefficiencies, increased vibration, and excessive heat.

Common Shaft Alignment Issues

For normal operation, both of the machines’ shafts need to be collinear, meaning that they are in the same line. When equipment is misaligned, several different conditions may occur:

  • Angular Misalignment – Shafts meet at an angle rather than being parallel, causing uneven load distribution.

  • Parallel (Offset) Misalignment – Shafts are parallel but offset either horizontally or vertically, increasing vibration.

  • Combined Misalignment – A mix of angular and parallel misalignment, often the most harmful.

  • Soft Foot – When one motor foot does not sit flat, the frame distorts as bolts are tightened, leading to shifting alignment.

  • Thermal Growth – As equipment heats up, alignment shifts from its cold condition, making “hot alignment” adjustments necessary.

 

The Laser Shaft Alignment Process

To check alignment of your machines, we utilize laser technology to accurately test the alignment. Here are the steps we use to align motors and generators to their mates:

Prealignment

  • Safety Check: We follow Lock Out Tag Out (LOTO) procedures to ensure no energy is present or available in the systems we are working on. Safety guards are then removed for access to adjustment points.
  • Mounting Check: All mounting surfaces and conditions are checked prior to installing the motor. Both the feet and the mounting base should be clear of any rust, paint or dirt.
  • Soft Foot Check: We use the Pruftechnik ROTALIGN Ultra iS to check the motor for soft foot (distortion of the equipment frame). ). If your motor or generator has soft foot, a false alignment of the bearings internally can occur cocking one or both bearings in the housing. This means that one foot could be tightened down and distort the bearing housing too much putting tension on the bearings. IEEE 1068‐2015 specifies a coplanar tolerance of 0.005 inches (0.127 mm) of the motor feet on a fully assembled motor. Click here to learn how a motor frame can warp via burnout oven stripping.

Shaft Alignment safety check

Alignment Steps

  • Fasten Brackets: Brackets are fastened to the driven shaft and the driving shafts.
  • Mount Laser: The laser is mounted to the stationary end and the receiver to the end that will be in motion.
  • Conduct Alignment Check: Using our Pruftechnik equipment, we select what types of equipment we are analyzing (ie. Motor + pump, motor + air compressor, and etc), input the dimensions of the equipment, and the points where the laser and receiver are located. We then manually and simultaneously turn both shafts 360 degrees by hand to conduct a test. The equipment takes a reading at every degree and calculates the level of movement as it goes around. The parameters are within thousandths of an inch. After the full 360 degree rotation, we can analyze the data on our equipment. The equipment will inform us to correct the machine positions.

Laser Shaft Alignment Adjustment

After the first adjustments, we check the alignment again, repeating the same alignment check until the machines are aligned within proper tolerances.

Sometimes a “hot alignment check” is necessary. Machines can grow or shrink during operation causing misalignment.  We run the equipment for a period of time to see if there is any thermal growth or shrinkage. It is necessary to align the motor or generator to its proper working conditions.

During the alignment process of a non reconditioned or new motor/generator, our technicians can find other problems. For example, if alignment is off from 5 to 6 thousandths of an inch after each check, this is a sign that the bearing housings could be loose. Our technicians will recommend if bearings need to be replaced, machining is needed, or other improvements to extend the service life of your machines. In some instances, we can also make recommendations on the remaining service life, based on the condition of the motor/generator or load.

Benefits of Laser Shaft Alignment

By investing in proper alignment, you gain immediate and long-term benefits:

  • Reduced vibration and noise

  • Lower wear on bearings, seals, and couplings

  • Improved energy efficiency

  • Extended equipment life

  • Fewer breakdowns and unplanned outages

Overall, alignment is a crucial step to maximizing the amount of profit you can get out of a motor, generators, or loads service lifetime. Improper alignment will cost you and your operation money!

Electric Motors and Generators Fail from Contamination

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Motors and generators are often mounted in a location that makes them susceptible to contamination. Over time, these contaminants cause major problems that can lead to bearing or complete motor failure. In this article, we’re going to outline four common scenarios in which contamination impacts motors and generators. We’re also going to provide solutions to keep your bearings and motors clean and free from contamination.

Breakdown of bearing lubrication or damage to the bearing surface.

Contaminants can breakdown your bearing lubrication and damage the bearing surface. This will cause a buildup of heat from friction. If the problem isn’t corrected, the added heat can lead to a catastrophic failure of your bearings and motor or generator.

Blockage of airflow or liquid cooling passages.

Motors naturally create heat which is caused by wasted energy. Motors and generators are designed with cooling fans, external blowers, vents, heat sinks, and liquid cooling systems to allow for heat to dissipate. Contaminants can clog the vents, cooling pipes, and cooling surfaces and prevent the motor from cooling properly. This added heat will eventually break down the mechanical and electrical components of your motor and can lead to motor failure.

Creating an imbalance to rotating components.

When contaminants stick to your motor rotors, fan blades, or other rotating components, they add excess weight. This weight creates an imbalance which can lead to increased vibration. The vibration caused by an out-of-balance rotating component will decrease the life of your bearings and could cause motor or bearing failure.

Deteriorating electrical insulation:

Not only will contaminants not allow your winding not to cool, the electrical insulation will breakdown over time. Contaminants will allow currents to discharge from conductors in the windings. In form wound windings, insulation tapes and varnish/resin carbonizes and breaks down. In random wound windings “pinholes” in the enamel insulation cause an electrical short when stress caused by contaminants break down the insulation. The result of insulation breakdown is lowering insulation resistance which can eventually causes an electrical short. Also on brushed motors and generators, brush dust can build up and cause shorts as well.

What are some solutions to preventing contamination in motors?

Electric Motor Contamination

Make sure your motor/generator is selected properly for the correct application

Example: This open vented motor filled up with corn dust. The motor has to be replaced with a totally enclosed fan cooled motor.

Electric Motor Contamination

Install and maintain filters in your air or liquid cooling system to prevent blockages

Example: This printing press motor filled with paper dust because it was not filtered properly.

Electric Motor contaminated by metal chips

Control nearby sources of contamination

Example: This motor was splashed with coolant and metal chips from machine tools.

Contamination from worn seal

Ensure bearing, cooling systems, brakes, or other motor system components are sealed properly

Example: This motors seal wore out allowing liquid to enter the motor.

Direction of electric motor

Ensure air patterns from cooling systems do not change allowing contaminates to travel in the wrong direction

Example: This motor is designed to run in one direction.

Motor cooling surface clogged with contaminants

Clean cooling vents and heat sink surfaces as needed without letting contaminates to ingress the motor/generator

Example: This motors cooling surfaces have clogged with contaminates.

Clean grease guns for lubricating motor bearings

Make sure bearing lubrication tools are clean and do not let contamination in

Example: These grease guns are kept in a clean storage area for lubricating motor bearings.

If you find your motor has been contaminated make a plan to send it in for minor reconditioning before it fails and becomes a more costly repair or replacement.

Example: A 1,600 kW generator being cleaned to remove contaminants.

Contamination in electric motor

Vacuum or blow out dust in brush applications per manufacturers recommendations

Example: Carbon/Graphite dust was not blown out of the motor on this brushed DC motor causing electrical problems.