Fasteners Lubrication Alignment Balance

Alignment

laser_align
Get with the program – get laser alignment equipment for shafts and sheaves.

Whether it is shafts and couplings or belts and sheaves, misalignment produces very aggressive and deleterious forces that typically show up as vibration at two-times the running speed frequency.  Angular, offset and combination misalignment forces can very rapidly wear out couplings, belts and bearings. This makes belt maintenance a constant nuisance and bearing failure, and the associated downtime, an all-to-common event.  Here are some common problems seen with misalignment on the plant floor.

  1. Lack of precision in alignment work instructions.  
    1. As is the case with fastener management, our maintenance work instructions typically don’t provide the specific fits, tolerances, quantity and quality details to guide the craftsperson through the process of achieving proper alignment of shafts and sheaves. Precision shaft alignment is typically defined as a function of speed.  At 3600 rpm, allow no more than 0.3 mils/inch of angular and 1.0 mils of offset misalignment. At 1800 rpm, allow no more than 0.5 mils/ inch of angular and 2.0 mils of offset misalignment. At 900 rpm, allow for no more than 1.0 mils/inch of angular and 4.0 mils of offset misalignment.
  2. Sloppy pipework.  
    1. If you require a hoist to pull pipe work into position for fastening, you’re producing misalignment forces.  Embrace the sage advice: “measure twice, cut once.”  This absolutely applies to pipework.  And when the pipework is intricate, spend the extra few dollars to employ qualified pipefitters who know how to properly size and fit piping while considering thermal growth, expected dynamic forces, etc.
  3. Failure to properly consider thermal growth.  
    1. Different materials have different coefficients of thermal expansion.  Failure to properly consider this leads to binding and misalignment.  Thermal expansion values should be incorporated into the work instructions and they should be customized for each piece of equipment.  Don’t rely on maintainers to remember all the numbers or have the luxury of time to do the calculations on the spot – even if they know how to do so.  They’re usually under the gun to get the equipment fixed and back up and running, which forces them to make approximations that compromise our efforts to achieve precision proactive control of machine health.   
  4. Too much reliance of flexible couplings.  
    1. Flexible couplings, such as spider couplings and belts, allow for more misalignment than rigid couplings but can lead to imprecise alignments.  Firstly, flexible couplings only divert some of the misalignment force from the machine components to the coupling.  Secondly, it makes couplings a high maintenance item.  Your production manager, and moreover, your customers, don’t care whether your machines are down due to a bearing failure or a coupling failure – you’re still down. Apply the same precision when aligning equipment with flexible coupled equipment that you would when aligning rigid coupled equipment.  Treat the flexible coupling as an insurance policy to protect against that which you can’t control – such as significant or unusual changes in temperature or the odd fastener problem.  Don’t make the flexible coupling your first line of defense – that’s just lazy.
  5. Failure to use precision methods.  
    1. In a crew of nine men and a supervisor, usually one man and the supervisor can do a highly precise job of aligning with dial indicators.  Once in a while, we run across that special maintainer – the “machine whisperer” who can precisely align a machine with a straight edge and gut-feel.  Don't manage the reliability of your equipment with one in 10 or one in 100 odds.  Get with the program – get laser alignment equipment for shafts and sheaves, keep it in good working order and train your people on how to use it properly.

 

For more information, call (662) 890-9392 or send us an inquiry.