Horizontal Shaft Alignment
The most common shaft to shaft alignment is horizontal alignment.
With the older D-Series (PHOTO - right), Easy-Laser® offered two programs for this, one is thestandard Horizontal Program that takes shaft measurements at the 9, 12, 3 o’clock positions. The other is EasyTurn™: a program that allows you to take readings with as little as 40 degrees rotation of the shafts, starting anywhere in the rotation. This is a great advantage when rotation is restricted because of piping and other factors.
With the new E-Series line of Easy-Laser systems we have actually made it easier!
The new wireless E-Series systems (PHOTO - below right) still offer the 9, 12, 3 o’clock method as well as EasyTurn method but now have added the Multi-point method which allows you to take multiple measurements. The more information you give (by taking measurements), the more accurate the result. It comes with a Quality Assessment scale to show you the qualtiy of the measurements (see PHOTO below middle left).
The process is just as easy with the E series systems. Again the display prompts you though the process. First you attach the measuring units to the shafts. Input the distances into the display unit (PHOTO - top left) ie. the distance between the measuring units, the distance to the centre of the coupling and the distances to the front and back feet of the movable machine. You even have the option to add the coupling diameter if you want to see a gap result. Record three measurements (PHOTO - middle left) using a minimum 40° of rotation for EasyTurn method, 9-12-3 o'clock method, or Multipoint method) and the display will show all the results both graphically and digitally on the screen. This screen (PHOTO - bottom left) is showing that it is reading live in the vertical plane. The green plus signs are tell the operator to add shim under the feet. To have it read live in the horizontal plane you simple rotate the measuring units to either the 3 or 9 o’clock position. If you can't get to either of those postions becuase of restrictive movement, you can force it live anywhere on the shaft.
Some laser systems like you to take measurements as you rotate the shaft. This is because they are more susceptible to back lash in the coupling. Other laser systems focus on speed. This is not an advantage for you-- the end user-- because if you think about it, it’s not a race. The goal is accuracy not speed of rotation. And ask your self if you have a better chance at hitting a moving target or a stationary one?
Many of you have used dial indicators to do alignment work. So you will know that the greater the distance between the dial indicators the more accurate the reading when you are doing the Reverse Dial method. With Rim and Face method the greater the distance between measurement the greater the accuracy. And so it is with laser systems: the greater the distance between the detectors, the more stable and accurate the reading.
All Easy-Laser® systems use dual beam technology. With dual beam lasers, the accuracy depends on distance A. Which is the distance between the detectors. The greater the distance, the greater the accuracy. With the single beam system, the possible accuracy depends on distance B between the detectors.
This distance is usually very short because both detectors are mounted in the same housing (normally about 50 mm). In reality, with the measurement units installed on each side of a coupling, distance A is, in most cases, always longer than distance B. [1: housing, 2: laser LED, 3: detector, 4: laser beam].
How accurately do you have to align Horizontal machine setups?
The required accuracy depends mostly on the types of machines you have and the speed. However, it is important to refer to the machine’s or component manufacturer’s specifications regarding this.
The coupling manufacturer specifies that their couplings can handle an large amount of mis-alignment means, nothing regarding how accurately you need to align. This flexibility is to compensate for offset settings and forces during the start-up phase. We think the coupling information is misleading so if anything use the machine manufactures specification or the standard chart below.
The speed of the shaft will determine the alignment tolerance. A machine running at 1725 RPM should have an offset betweem 2.0 and 4.0 mils or thou and an angular error of between 0.5 and 0.8 mils or thou per inch.
If the machine is running at 3600 RPM the tolerance would be between 1.0 and 2.0 mils or thou for the offset and 0.3 to 0.6 per inch for the angular error.