When craftsmen are given the task of laser alignment, quite a few assumptions are made. One very common assumption is that now that a laser system is being used, anyone can do an alignment. Another is that since a laser is being used, everything is alignable. Put a laser system on an unalignable machine and you will still have an unalignable machine, only with an expensive laser alignment system attached to it. A laser alignment system does NOT guarantee that a machine is alignable!!! (Actually, all machines are ultimately alignable, if only you throw enough time and resources at them- perhaps an entirely new base or foundation is needed, and/or redoing the entire piping. The question is, is it worth it in some cases? The point is, that just because you put a laser on a machine, that does not make it instantly alignable, vanishing all other problems.)
However, a laser alignment system, combined with a skilled and trained craftsman and a good alignment procedure, will greatly expedite alignments and help determine if a piece of equipment is alignable at all. The following is a tried and true procedure that will greatly expedite alignments.
Pre-alignment checks are critical in ensuring successful alignment. All surfaces should be clean and burr-free with metal-to-metal contact between the feet and shims, and the shims and base. Shim packs should be consolidated to three or four shims per foot. Jackscrews should be installed. A concentricity and runout check should also be done on the coupling and shaft. It is also a good practice to check the base for flatness.
The next step is to accomplish a rough alignment. Use whatever method that you prefer to get the machines reasonably close, or “eyeball” clean. A straightedge will work on some couplings in short-coupled machines. On machines with spacer couplings, the laser and a tape measure can be used very effectively. The purpose of this step is to remove gross misalignment and ensure that the laser and detector are in line enough to take readings. (Note that the best laser systems offer range extension so even rough alignment can easily be done with the laser.)
After your rough alignment has been accomplished, a rough soft foot check is in order. Eliminate any obvious rocking and fill any obvious gaps. This should be done with all hold-down bolts loose. Now it is time to use your laser alignment system. Make sure that all required dimensions are entered accurately and that initial alignment measurements are repeatable. Assuming you still have a rough alignment, a final soft foot check is in order.
Follow your laser system’s recommendations for this. The ROTALIGN® ULTRA even features a comprehensive soft foot wizard that guides you through the entire process, diagnoses the condition, and suggests a solution. After any corrections are made, retighten all hold-down bolts, then recheck each foot individually with all the others tight.
We recommend a tolerance of 2.0 mils or less. Now for the final alignment: The first correction that should be made is getting the vertical plane in tolerance. When making shim corrections, monitor the horizontal plane to make sure your machine does not move laterally too much. Once you are satisfied the vertical alignment is in tolerance, proceed to final horizontal corrections. Leave the hold-down bolts snug (not tight). They do not need to be all the way loose to make effective horizontal moves. This is where good jackscrews become invaluable, Try to avoid hitting machines with hammers. When the machine is within tolerance alignment is complete. Save the alignment file for documentation and future reference.
Many years of involvement with machinery alignment reveal that this is the best and fastest procedure for precision alignment. Each step is necessary and important in accomplishing the next step. Take your time and be diligent and you will succeed in your alignment.
Alignment by Ana Maria Delgado, CRL