This is a question that comes up surprisingly often in our training classes. The question is usually regarding Thermal Growth offsets (dynamic movement) and shaft alignment tolerances. There are several ways to obtain the data in question. The easiest and most readily available would be the equipment manufacturer. Most companies will supply specific offset and alignment instructions for their equipment. Below is the recommended Thermal Growth settings for the Goulds 3196 Series centrifugal pumps taken from the “Model 3196 i-Frame Installation, Operation, and Maintenance Manual”
There are also other ways that VibrAlign offers to you to obtain Thermal Growth information. We have several free apps available through iTunes or Googleplay, two of which are Therm Align and AlignHot, for determining accurate thermal offsets. In addition, Fixturlaser has built into the XA Pro, XA Ultimate & NXA Pro Alignment Systems the ability to accurately measure the change in machinery positions from cold to hot (offline to running) and assess the proper offsets or target values.
In addition to dynamic target values, the manufacturer may also include recommended alignment tolerances. The instructions that are commonly given are in dial indicator alignment terminology, either Rim and Face or Reverse Dial. Include below is the guideline for alignment tolerances taken from the same Goulds 3196 installation manual given as Reverse Dial Indicator Values.
As our clients and students have discovered, once trained in the use of the Fixturlaser laser shaft alignment tools, the alignment process is much faster and less complicated than with dial indicators.
That being said, the basic and essential “truths” of doing a proper precision shaft alignment using a laser system or dial indicators remains the same;
- Clean. Remove dirt, debris, burrs, etc. from the base and the feet of the machine.
- Measure your shims. (http://thealignmentblog.com/blog/category/best-practices/shims/)
- Pre-alignment steps. (http://www.youtube.com/watch?v=U_04dRQZUD4&feature=c4-overview-vl&list=PL8FBFF24C6411D13A)
- Measure, correct the misalignment, verify and document the alignment.
In short, look to the machine maker’s literature to obtain the specific information that you seek. Those little sheets of paper in your coupling box or taped to the pump may have all the information that you need. If not, consult web sites and manuals to determine the appropriate specifications to complete your alignment correctly. And remember, if you need help, call us, we are here to help!