As the defect continues to worsen it will reach a point where the energy in the FFT will reduce to where the peaks are no longer present, but you see mounds of energy resembling broadband noise.  This is due to the clearances in the bearing opening up and the excessive clearance beginning to resemble more of a looseness pattern.  Also remember that the generated frequencies not always (and in fact ) rarely match the calculated frequencies of the bearing.  This is due to the calculated bearing fault frequencies coming from known bearing geometry.  When the bearing starts to deteriorate the geometry begins to change and the actual frequencies generated don’t match the calculated frequencies.  However, the patterns will match and be very close.

Shimming the feet will rarely solve the problem completely; rather, the correct solution is to eliminate the undesirable pipe stress. “Stress” is the force acting on something, while “strain” is the deflection or distortion resulting from the stress. A soft foot condition means you have machine frame strain, and pipe stress is just one of several examples of this. When the machine casing is distorted, the internal alignment between the bearings is changed and the shaft is deflected. This produces enormous stress on the bearings and increased vibration in your machines, resulting in premature wear and tear as well as loss of efficiency. Your seals and bearings will fail much faster. If a significant soft foot condition exists, a good alignment of the centerlines of the shaft rotation is almost pointless. The machines will still fail more quickly and lose efficiency. How do we diagnose and fix this?

The trick lies in knowing how to recognize that a pipe strain problem exists. The behavior of a machine with pipe strain differs significantly from one whose soft foot condition is caused by one of the more traditional shimming problems or unevenness of base or feet. Fortunately, there is an easy measurement solution: The Pipe Strain Wizard in the OPTALIGN SMART. The Pipe Strain Wizard will guide you through the all of the necessary steps to quickly and easily ascertain whether a pipe strain problem exists and measure its precise impact on the shaft alignment.

Essentially the process involves taking an initial reference reading of the shaft alignment condition. Thereafter the piping is completely loosened and a second reference reading is taken. The wizard then calculates the difference and yields the results.

These results can be documented in a full color Pipe Strain report printed directly from the OPTALIGN SMART to a USB memory stick as a PDF file.

Any impact on the alignment of more than about 2 mils indicates a pipe strain problem that should be dealt with. Correcting pipe strain is a task for an experienced pipefitter who must see to it that connecting and torquing the piping should not move the machine from its rough aligned condition, nor distort its casing in any way. Proper pipe hanging techniques and a good knowledge of calculating and designing “Dutchman” spacers is essential.

Vote for our product and tell everyone you know to vote! Voting ends March 7, 2012. Only one vote per email address permitted.

To vote, go to http://www.newequipment.com/votekingawards. Voters can choose from multiple product entries in 11 distinct categories, ranging from assembly, controls and electronics to facilities, material handling, safety and more.  Our ROTALIGN ULTRA is product #19 under the Facilities/Maintenance/Plant Operations category.

“NED received an overwhelming response to the King Awards competition,” says Bob King, Chief Editor. “With so many great and innovative industrial products nominated, the readers of New Equipment Digest and the expert panel of judges are going to have a difficult time choosing the gold, silver, and bronze winners from such a wide variety of entries in the 11 categories. Everyone is looking forward to the voting and the final selections.”

“The KING Awards recognizes the best-in-breed products that help manufacturers be more efficient and more competitive in today’s global economy,” according to John DiPaola, Vice President and Group Publisher of New Equipment Digest. “These companies who have entered are the companies who are making manufacturing happen.”

Winners will be announced in the April 2012 issue of New Equipment Digest and displayed at IndustryWeek’s Best Plants Conference, which will be held April 23-25 in Indianapolis, IN.

Being base-bound means you need to bring the machine down to get it aligned, but you can’t: the machine feet are down against the base and there are no more shims left to remove from under them.

Are you in a quandary with either of these situations? No problem! You have five possible solutions:

• Open up the holes in the feet.
• Turn down the anchor bolts.
• Redrill and tap new holes in the base.
• Make an “Optimal Move”.
• Make a “Rolling Move”.

Let’s take the last one first. Making a rolling move of a bolt-bound machine simply means shimming up one side of the machine but not the other (or lowering one side but not the other.) This displaces the horizontal centerline of rotation of the shaft. But this is a big no-no! Do not do this! It will create angled soft feet and distort the machine frame when you tighten them because the feet are no longer evenly supported. Moreover, with gearboxes you may change the gear mesh pattern and destroy the machine. Many machines must be carefully leveled in addition to being aligned, so rolling moves are out!

Download entire article including making an ”Optimal Move” with ROTALIGN ULTRA.

Orbits have historically been used to measure relative shaft movement within a journal-type bearing. The shape of the orbit told the analyst how the shaft was behaving within the bearing as well as the probable cause of the movement. This was accomplished using proximity probes usually mounted through the bearings with a 90-degree separation and a tip clearance set to around 0.050 inches. With today’s modern analyzers, it is possible to also collect an orbit using case-mounted velocity probes or accelerometers to see how the machine housing is moving. Another way of putting it would be the orbit represents the absolute path in space that the machine housing moves through (see Figure 1). 

Figures 1 and 2

Read my entire article “Using Orbits for Condition Monitoring”.