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In general, laser shaft alignment systems have increased the ability to eliminate misalignment defects.  There are many systems on the market, with varying capabilities, but the core benefit has been that the computer and laser work together to create an alignment report that can be used to assess and determine corrective action.

With advances in the interface and measurement technology, the skill required to take measurements has been reduced when compared to older methods, such as dial indicators.  Thus, more users can perform the job with less training for the task of gathering the measurements.  Unfortunately, this convenience has in some cases resulted in the good practices of the fundamentals of shaft alignment falling by the wayside, given the perceived ease of use.  It has gone so far that some systems have marketed the idea that alignment can be done faster and in fewer and fewer steps to the point of rough alignment not even being necessary!

Is rough alignment not necessary?!?!

The claim is that if the laser can measure the misalignment without the laser going outside the detector, the alignment can be determined and the entire correction is done once.  Anyone who has done at least one alignment in the field knows that this is far from the truth as you can’t escape physics in shaft alignment.

Depending on the setup, dial indicators could measure far more misalignment than a laser setup.  Let’s say you had a situation where the indicators showed 300 thou misalignment.  If you performed the right calculation would you expect to move the machine one time and get it within tolerance?  Absolutely not!  The reason is that the two shafts would be so strained as to the force required to bring the machines back together, that the coupling would be impossible to install, the shaft would deflect, and the forces would cause incorrect soft foot measurements.  Again, you can’t escape physics.

The solution is to rough align the machine!  It’s a best practice as per our field-proven 5-Step Shaft Alignment Procedure, which applies to all shaft alignment tools.

What about measuring severe out-of-alignment conditions with a laser alignment system?

First of all, if you are aligning an existing machine that has been running and did not experience a failure, I will give the previous alignment technician the benefit of the doubt that it was not severely out of alignment, and 99% of the time, you will not encounter the laser going out of the detector.

Second, if it is a rough alignment there is a chance it could move out of alignment for any laser shaft alignment system, single or dual beam.  In rough alignment, you will typically align with a straight edge and most likely be within laser detector range to get an approximate set of readings.  In one case, I checked the rough alignment of the machine with a 27-foot separation between machines (shown below.)

Rough Alignment

The lasers moved 8″ from the detector on both sides.  Regardless of whether you had a single beam or a dual-beam system, there is no system on the market with a detector that is 8″ in size to handle this rough alignment, nor is it necessary, provided you have a dual laser beam type laser alignment system.

How do you rough align with a laser alignment system?

Fortunately, I used the Easy-Laser XT770 which features a dual laser configuration.  Using a process called “coning” I was able to rotate both shafts from 90 to 270 degrees, move lasers to the middle of travel and then use them as a visual indicator to align the machines until both lasers hit the center of both detectors.  In one vertical and horizontal movement, like magic, the axes of rotation were rough aligned.  The millwrights on hand were amazed at how quick, efficient and intuitive this method was – which can only be done with a dual laser alignment system.  This means the machines were roughly aligned 27 feet apart without dealing with a complicated movement of the laser during measurement as the single laser systems require.  We were then able to do a full 360-degree measurement, get the values, and start the alignment corrections and finish the alignment as per the 5-Step shaft alignment procedure.

by Diana Pereda

We welcome you to read the previous blog in this series, “What is Machine Train Alignment and How Important Is It? Part 2”

 

ANALYSIS 2: THE REFERENCE MACHINE IN THE TRAIN CANNOT BE MOVED

 Now we have to face the situation of the big 172 mils moves at DF2, Compressor 3 back foot. For this, we are going to make use of the XT770 Adjustment Guide to predict what will be the minimum moves needed at Compressors 1, 2, and 3 to get the misalignment to excellent tolerances.

Here is a brief description of what is the Adjustment Guide and how it works:

It is Firmware utility built into the Easy-Laser XT770 alignment system to aid the aligner to predict what will be the minimum moves or shim changes required to align all the machines in the train to get the alignment at each coupling within tolerance when there are limitations to adjustment such as when Machine 1 cannot be moved in a 3-or more machine train. Let’s explore what can be done in our alignment.

As stated in Blog1 the calculated corrections at Machines 2, 3, and 4 are to bring the whole train to alignment to Machine 1. We also spoke on how valuable this information is.

Now that we know ‘the whole picture’ of the train and we know that Machine 1 cannot be moved, we can make ‘virtual moves’ and predict the minimum required moves at each pair of machine feet to get the alignment between consecutive machines to excellent tolerances. See examples in pictures 7, 8, 9, 10, 11, 12, and 13.

When we first invoke the Adjustment Guide we see a graph pictured below.

Machine Train Picture 7
Picture 7

Allow me to describe what we are looking at in Picture 7. Several things:

  • The actual misalignment at couplings 1 and 2.
  • Machine 1 feet, AF1 and AF2 are ‘Locked’ because they cannot be moved.
  • We see empty white rectangular boxes under BF1, BF2, CF1, and CF2.
  • Underneath the white rectangles, we see the needed adjustments to make to bring machines 2 and 3 into alignment with Machine 1.
  • We see the interval set up, set to 1 mils by default, and of course adjustable up to 125 mil increments every time you press the + or – icon. In other words, user-adjustable to save time.
  • The left and right arrows allow the user to move down or up on the machine train.

Having said this, we used the arrows to ‘virtually move’ BF1 and BF2, see below.

Machine Train Picture 8
Picture 8

Picture 8 shows the final virtual adjustment on BF1 and BF2 to get Machine 2 to ‘Excellent’ alignment relative to Machine 1. Please note a couple of things:

  • We needed to move machine 2 only 19 mils at BF1 and 31 mils at BF2 instead of 22.5 mils and 45 mils to get to excellent alignment. And more importantly…
  • It allows us to leave the angularity of machine 2 with an angle such that machine 2 ‘points towards machine 3’, thus minimizing the moves at machine 3 to get it to perfect alignment with Machine 2.
Machine Train Picture 9
Picture 9

Picture 9 above shows the ‘virtual moves’ needed at CF1 and CF2 to get Machine 3 aligned to excellent tolerances with respect to Machine 2.

Please note that to achieve Excellent alignment the move at CF1 is only 53 mils instead of 78.3 mils and at CF2 it is 86 mils instead of 132.3 mils.  Also note that we left Machine 3’s angularity in such a way that Machine 3 points towards Machine 4, thus minimizing the moves that will be required at Machine 4.

Picture 10 below shows the last 2 couplings and DF1 and DF2 with ‘empty’ values.

Underneath the empty rectangles that are waiting for the input of the virtual moves, we see the required move to bring Machine 4 (Compressor 3) into alignment with Machine 1, which are, DF1 150 mils and DF2 172.5 mils. However; what is needed, as pointed out before, is only to bring Machine 4 into alignment with Machine 3, not with machine 1. See Picture 10 below.

Machine Train Picture 10
Picture 10

We continue the process as we did before making ‘Virtual Moves’ at DF1 and DF2 in any order until excellent alignment is achieved. See Picture 11 below.

 

Machine Train Picture 11
Picture 11

Picture 11 shows that we have ‘Virtually Moved’ DF2 90 mils.

We will proceed to move DF1 and DF2 in any order until we reach excellent alignment. Remember the ‘increment’ is adjustable, hence when getting close to alignment it can be lowered to 1 mil to make more precise moves.

Machine Train Picture 12
Picture 12

Picture 12 shows that we have moved DF1 50 mils and DF2 90 mils.

Machine Train Picture 13
Picture 13

Picture 13 shows the moves required at DF1 to be only 92 mils instead of 150 mils and for DF2 only 93 mils instead of 172.5 mils to achieve alignment to tolerance.

As we can see, the Adjustment Guide utility is a tremendous aid that helps the aligner predict what is going to happen and most importantly find out if he or she will be able to obtain his or her goal.

 

by Diana Pereda

Shaft Alignment is a critical step in any world-class maintenance program, and when done properly, can help decrease unscheduled downtime and keep equipment running longer and more efficiently. This means machines need to be aligned within the recommended tolerances based on the RPM of the equipment. However, this is sometimes easier said than done, especially if any residual soft foot is present, or due to bad geometry in the movable piece of equipment. If you find yourself struggling to complete an alignment to tolerance, here are some tips that, when combined with Ludeca’s 5-Step Shaft Alignment Procedure, may help you complete the alignment faster and with less frustration.

  1. Get the position of the front feet close to the alignment offset tolerance. Once the front feet are close to or within the tolerance value, complete the alignment by correcting the rear feet only.
  2. Try to leave both the front and rear sets of feet with positions having the same sign, either positive or negative.
  3. It is not desirable to leave the position value of the front feet higher than the position value of the back feet. This means that the final position value of the rear feet should be larger in value than the position of the front feet.

The following scenario is an example of how these rules can be applied to help you complete an alignment to precision tolerance as defined by the ANSI standard (ANSI/ASA S2.75-2017/Part 1.) This standard defines three acceptance levels: Minimal, Standard, and Precision. These acceptance levels, as well as the corresponding tolerance values for 3600 RPM, are shown below in Figure 1. The scenario below was prepared utilizing an Easy-Laser® XT770 Shaft Alignment System and the Adjustment Guide feature. Our Easy-Laser XT Series is one of the few laser alignment platforms on the market today with the new ANSI alignment tolerances built-in giving the user the freedom to choose between traditional tolerances, the new ANSI standards, or custom tolerances.

 

ANSI ASA S2.75-2017 Tolerances for 3600 RPM
Figure 1: ANSI/ASA S2.75-2017 Tolerances for 3600 RPM

In Figure 2 we have our shaft alignment results measured on equipment running at 3600 RPM, where the position of the front feet is at +1.0 mils and the position of the rear feet is at –0.6 mils. This creates misalignment at the coupling with an offset measuring +2.6 mils, which puts us in the Minimal tolerance range. We need to make some adjustments to improve the alignment in order to reach the precision tolerance range, but how? Let’s try following the recommended tips!

As found results
Figure 2: As-Found Results

If we look at the position of the front feet in Figure 2 we see that we are at +1.0 or 1.0 mils too high. Since the position of the front foot is already less than the desired Precision Offset Tolerance Value of ±1.3 mils (shown in Figure 1), Tip 1 says we should leave the front feet where they are and complete the alignment by correcting the rear feet only. Looking at the position of the rear feet in Figure 2, we see that we are at –0.6 or low by 0.6 mils. Using the Adjustment Guide feature on the XT770, let’s see what would happen if we add 1 mil worth of shims to the rear feet.

Adjustment Guide adding 1 mil to rear feet
Figure 3: Adjustment Guide adding 1 mil to rear feet

In Figure 3, we add 1 mil of shims to the rear feet of the alignment result that was shown in Figure 2 bringing the new position of the rear feet to +0.4 mils with the front feet still at +1.0 mils. Although both feet now have the same sign, satisfying Tip 2, we see that this still produces an offset measuring 1.5 mils at the coupling, putting us within the Standard alignment tolerance range. Although we did improve the alignment slightly, we still are outside of the Precision alignment tolerance that we are pursuing. What would happen if we added another 1 mil to the rear set of feet bringing the final position of the rear feet to +1.4 mils?

Adjustment Guide adding 2 mils to rear feet
Figure 4: Adjustment Guide adding 2 mils to rear feet

Now in Figure 4, we have added 2 mils worth of shims to the rear feet of the alignment result that was shown in Figure 2, bringing the final position of the rear feet to +1.4 mils with the front feet still at +1.0 mils. Now we see that the position of both the front and rear sets of feet are positive in value satisfying Tip 2. Additionally, the positional value of the rear feet is greater than the positional value of the front feet, thereby also satisfying Tip 3. Now if we look at the misalignment measured at the coupling, we have an offset measuring just 0.6 mils and putting us well within the desired Precision alignment tolerance. In addition, the angularity value has also decreased and is well within the precision alignment tolerance range. Note also that adding shims is always easier than removing them, especially if you do not have enough thickness of shims left under the feet to make the desired negative correction possible.

We hope these three tips will make your task of precision aligning machines much easier.

Request your complimentary copy of our Shaft Alignment Fundamentals Wall Chart which highlights the ANSI/ASA Shaft Alignment Tolerances as well as information and guidelines for the implementation of good shaft alignment of rotating machinery, best practices, soft foot, tolerances, thermal growth, and much more!

by Diana Pereda

We welcome you to read the previous blog in this series, “What is Machine Train Alignment and How Important Is It? Part 1”

 

ANALYSIS 1: ALL MACHINES IN THE TRAIN CAN BE MOVED 

Since ALL 4 machines in the train can be moved we have many options.

Option 1:

Let’s see what the minimum moves will be for the whole train. How we do that with the Easy-Laser XT770? We simply make ALL 8 feet in the train movable. NO LOCKED FEET in the train. See Picture 3 and Picture 4 below.

Machine Train Picture 3
Picture 3
Machine Train Picture 4
Picture 4

What can we conclude from those two pictures? A couple of things:

  • What we see in the graphs is what we call: ‘The Optimized Alignment Line’. Simply the XT770 finds the Alignment Line that will minimize ALL MOVES. The proof that we are looking at an Optimized Line is that the SUM of the Absolute Values of the Negative and Positive corrections (moves) is the same. In those pictures, we see that the Negative Values add to 64 mils and the Positive Values add to 64 mils.
  • We see that the big 172 mils move at DF2 is now only 6.4 mils.
  • We also see that the biggest move in the train is at AF1 (Turbine Back Foot) only 31 mils.

Option 2:

For example, we can explore if we can minimize the Turbine move. The XT770 allows you to ‘Lock’ any feet. We Locked AF1, which was the biggest move in the Optimized view, and CF1 arbitrarily. See Pictures 5 and 6 below.

Machine Train Picture 5
Picture 5
Machine Train Picture 6
Picture 6

The XT770 calculates the moves for the remaining feet you are to move. As you see, not a bad option but not as good as moving both Turbine feet.

As mentioned above, in addition to moving ALL feet you can ‘Lock’ any feet to be able to analyze the best option. Going through all the possible combinations will make this blog extremely long torture for the reader.

by Diana Pereda

Shimming

Saving short-term money at the cost of long-term loss could never be a good idea. Soft foot is one of the most prevalent problems in rotating machinery, and the improper use of shims is one of the bad guys. This is way too common and is the cause of countless machinery problems worldwide. But let’s not let that happen. Instead, let us guide you through the ideal shims procedure, for an easier alignment task.

1. Initial check

For safety, always remember lockout and tagout of the machine. Then you can go about inspecting the foundation, grout, and baseplate with your eyes. If there is rust, scale, paint, or dirt, remove all of this from under and around the feet. Then you replace damaged shims with new ones, that are corrosion and crush resistant.

2. The right shims and the right number!

Don’t fall for the temptation to use homemade or low-quality shims! In the long run, this will cost you more than you gain short term. Usually, you will also need more shims if you use homemade ones. Use as few shims as possible. Three pre-cut shims should always be enough; in extraordinary situations, four could be needed. The fact is that using too many shims can, in itself, cause soft foot.

The use of anything other than high-quality shims is the main factor when it comes to machines being worn out beyond salvation. Pre-cut, stainless steel shims are perfectly flat and will, as a bonus of sorts, also prevent corrosion.

3. Measure and insert

Use a micrometer to measure the thickness of shims 1 mm and thicker. These thicknesses are nominal and not necessarily exact. Insert the pre-cut shims under the foot of the machine until they touch the bolt. Withdraw slightly.

4. Shim size

Use a shim size that adequately supports the load zone of the foot. Whenever the contact between the underside of the machine’s feet and the surface of the base plate or frame is less than perfect, we have what’s called soft foot. Ever sat at a wobbly table? Then you know. The annoying situation where one leg fails to reach the floor is bad enough. For a machine in an industrial context, this is more than just irritating; it will lead to damage if not taken care of.

5. Sandwich

With pre-cut shims, you’ll get a safer and easier machine alignment as well as better machine performance. Burr-free edges and rounded corners prevent injuries from occurring. Sandwich thin shims between thicker ones. If you have used high-quality shims, your machine should now be almost aligned. You are ready to move on to fine adjustment, i.e., aligning your machine using all the tricks of the trade.

Download our Shimming Best Practices Infographic which outlines 7 things to consider when using shims for machine installation or machine alignment plus Step Shimming. 

Thank you Roman Megela with Easy-Laser for sharing this informative article with us!

by Diana Pereda

Do your washers resemble cones?

If so, you could be falling victim to a common headache experienced in some shaft alignment jobs. What could mistakenly be diagnosed as soft foot or coupling strain, “dished” or “cupped” washers center themselves in the feet causing the machine you are aligning to move laterally as you tighten the hold-down bolts. Prevent this from happening by performing pre-alignment checks and replacing any washers that exhibit this defect. Also, check the surface of the machine feet for similar grooves that have been cut by washers in the past. These grooves can also cause this effect and make your alignments challenging.

washer figure 1
Washer Figure 1

 

by Diana Pereda

What is Machine Train Alignment?

Machine Train Alignment is a multi-coupling alignment where two or more consecutive machines can be adjusted.

For example, a 3-coupling train (4 machines), such as a Gas Turbine driving 3 Compressors.

NOTE: A 2-coupling (3 machine) train such as a Pump–Gearbox–Motor, where the Gearbox in the middle is determined to be NON-movable, is NOT a Machine Train; it could be treated as one but that is not the best option. It is best to treat this as two separate alignments using the Gearbox as the ‘Stationary Machine’. In one alignment, align the Pump to the Gear-Box, and in the other, align the Motor to the Gear-Box.

NOTE: Normally, most laser shaft alignment tools will use the first machine on one end of the train, say the left machine, as the Reference Machine, and after collecting the data at all couplings the alignment tool will combine all the misalignment values to calculate the required moves to align ALL the machines in the train to the original reference (alignment line), in most cases machine number ONE.

Is this the goal we are trying to achieve? NO! We are trying to align two machines next to each other. Then, what is the value of the machine train program? A TREMENDOUS VALUE, as it gives the aligner “the Overall Picture” of how all the machines sit with respect to the reference line and therefore also how they sit with respect to each other. Why do we need to know this? Because we need to avoid getting ‘Bolt Bound’ or ‘Base-Bound’.

We will use an Easy-Laser XT 770 Laser Shaft Alignment tool with data collected in a 4 machine train (3 coupling) for this blog. In a four-machine train, after reading the misalignment at each of the three couplings, we found the following Horizontal Misalignment values versus the entered Misalignment Targets that were desired. See Pictures 1 and 2 below.

Picture1-alignment tool depicting 2 couplings in 3 coupling train
Picture 1

What we observe in Picture 1 is a laser alignment tool depicting the first TWO couplings (3 machines) in the THREE coupling train. We see that the first machine is the reference (Stationary Machine), we observe both the misalignment at couplings 1 and 2, and the required Horizontal Moves to align machine number TWO (BF1 and BF2 moves) and machine number 3 (CF1 and CF2 moves) to the reference machine number 1.  We begin to see a big move at CF2, 132 mils (Thou). CF2 is the Compressor #2 Back Foot.

Picture2-misalignment at coupling 2 and 3 with corrections
Picture 2

What we observe in Picture 2 is the misalignment at couplings 2 and 3 and the required corrections to bring all THREE machines to Machine ONE, the original reference (Alignment Line). See a possible problem now? Do you think we will be able to move DF2 172 mils (Thou)? DF2 is the Compressor 3 Back Foot.

In my next blog, we will then see how easily we can analyze and solve the apparent bad situation we are facing.

NOTE: Please realize that the pictures you saw are ‘GRAPHS TO SCALE’ of the misalignment. Observe the scale on the left side of the graphs.

by Diana Pereda

As stated by Daniel Keys Moran, “You can have data without information, but you cannot have information without data.” The driving factor for any reliability program is data; but how do you gather and record the right data to achieve your maintenance and reliability goals? By documenting and generating clear reports with the necessary data. This will permit statistical trends to be developed that can improve uptime and productivity as well as justify repair or replace decisions.

First, let us look at what information should be gathered and documented, followed by how and where you should store the data so that you can use this data over time to develop trends and Key Performance Indicators (KPI’s) to drive your reliability program forward. Harness the data coming out of your maintenance operations and turn it into actionable information that will make a difference in the way you work and what you accomplish.

What data should be captured?

The following list describes the equipment and information that is necessary to make informed decisions and drive the improvement process forward in a maintenance program:

  • Instruments used for measurement
  • Person(s) completing the task(s)
  • Description of the asset
  • Date and time
  • Tolerance requirements
  • As-Found and As-Left measurements
  • Reference to the standard used
  • Appropriate signatures

 

Sample report for Reporting Blog Page 1
Page 1
Sample report for Reporting Blog Page 2
Page 2

 

 

 

 

 

 

Sample report for Reporting Blog Page 3
Page 3

Where should my data be stored?

Now that we’ve assembled the needed information, we need to store this data in a way that we can easily access it and refer back to it to identify problems and develop solutions. The preferred storage location should be within your company’s CMMS (Computerized Maintenance Management System.) If your CMMS is configured properly, you may be able to store the As-Found and As-Left measurements directly in the work orders to trend them, thereby allowing the CMMS to automatically create work orders when an asset is out of tolerance. The next alternative is to link the report to a work order and/or asset, allowing the information to be easily accessed within your company. If you don’t have a CMMS, another option is to create a folder structure on a shared drive where the reports can be saved. Keep in mind that there should be a consistent naming structure that is followed by everyone with access to the shared drive so the reports can be ordered correctly and easily located. This will require some training.

What are the Key Benefits?

The goal of any maintenance organization should be asset management with the equipment operated and maintained in a cost-effective manner. Creating detailed reports starting from when the equipment is first installed and continuing throughout the life of the asset allows you to predict when failures may occur so that you can effectively plan and correct the issue in the most efficient manner, in advance of an unplanned failure. With the right data gathered and properly stored, organizations can analyze and develop maintenance strategies to ultimately increase equipment availability, decrease production downtime and generate greater profits for the company. These detailed reports allow communication between operations and maintenance and drive continual improvement throughout the organization by identifying, mitigating, or preventing losses. Ludeca provides a wide range of reliability technologies that generate detailed reports that can be easily shared within an organization to help you Keep it Running.

Visit our Knowledge Center for resources and tools to help you succeed when implementing and using our maintenance technologies! Watch our video tutorials, download infographics, plus explore other helpful information to reduce equipment failures and downtime. 

by Diana Pereda

Belt Pulley Alignment

Belt-driven rotating equipment is commonly found in all types of facilities. Typical applications include rolls, fans, motors, shafts, and blowers. It is important to maintain that equipment in order to increase its reliability. Maintenance is essential in today’s industrial environment to ensure assets and equipment are running as reliably as they should.

Like any part that can wear over time, belt-driven equipment should be periodically inspected.  This includes the inspection of the pulleys, sheaves, and belts. Worn belts and sheaves should be replaced. Belts should be properly tensioned and the equipment aligned.

It is important to have quantitative values so that the condition of the machine can be evaluated and monitored over time. One way this can be accomplished is through ultrasound and vibration readings. Another value that can be quantified is alignment and belt tension. Belt tension is commonly quantified by force and deflection and determined during the installation of a new belt.

Pulleys and sheaves be should be properly aligned. However, the most common methods rely on pass/fail methods.  This includes straight edge and visual laser guides. While they are better than not performing an alignment check, how does one quantify the degree to which the alignment is accomplished?  In the same way that it is important to quantify shaft alignment, belt alignment should be quantified as well. This supplies numerical information which the reliability engineer can trend and decide the condition of, in order to plan, rather than react to a maintenance operation.

Our Easy-Laser XT190 belt alignment tool can carry out this task and supply numerical values for the current belt alignment condition. A laser transmitter and receiver are placed on the sheaves and pulleys to be aligned. The results are instantaneously projected through the iOS and Android app to supply the current alignment condition in real-time as well as the required corrections. An added benefit is that the users typically only need to access each pulley without having to pull the entire coupling guard off (provided proper lock-out and tag-out procedures are followed). With this advantage, one does not need to visually figure out the alignment as it is all displayed in the app.

The result is that alignments take less time and the reliability engineer can have quantitative data to decide the current and trending alignment condition. This one tool can help move belt-driven rotating equipment from the reactive maintenance stage to the planned and eventually to the precision domain.

Download our Pulley Alignment Guide Plus 5-Step Procedure for information on the implementation of good pulley alignment of belt-driven equipment including terminology, alignment methods, belt maintenance, storage, and tensioning as well as a 5-Step Sheave/Pulley Alignment Procedure.

by Diana Pereda

We previously discussed in our series of soft foot, Types of Soft Foot: Part 3 Squishy Foot. In this follow-up blog, we will discuss Induced Soft Foot.

What is induced soft foot?

Induced Soft Foot: Occurs when stress-induced external forces such as pipe strain, electrical connections, or severe misalignment combined with a stiff coupling pull or push on the machine creating a distortion of the frame.

The precise alignment of rotating machinery is affected by many factors and components. From the very foundation the equipment is mounted upon to the equipment itself, and extending to anything connected to the machine. Because of the tightness of the tolerances that are aimed for during these alignments, it takes little to put stress on a machine.

In rotating equipment, the internal alignment of the bearings that hold the shaft in place is very precise. As we’ve seen in this series the mating between the feet and mounting surface can stress these internal components and clearances. What else can cause internal misalignment of the bearings?

Condition 4: Induced Soft Foot

  • Caused by external forces such as pipe stress, coupling strain and strain from conduits and braces.
  • Correct by removing any external forces on the machine.

Soft Foot - Induced Picture

Download our Soft Foot Find-and-Fix Infographic which outlines the of types of Soft Foot including causes and corrections.

by Diana Pereda

When performing shaft alignment, the best way to accomplish the horizontal (side-to-side) corrections is using jack bolts. You do not want to hit your machines with a hammer in order to move them. Always remember to back off the jack bolts on the opposite side. Remember that once you are done with your side-to-side correction, we recommend that you always back off all jack bolts after the alignment is completed and the anchor bolts are tight.

Where to put the jack bolts on your machine?

Place the jack bolts in such a way that they do not interfere with the shimming and allow you to pivot the machine you are moving. See figures 1 and 2 below.

Correct positions of jack bolts

Picture1-jack bolts
Figure 1
Figure 2

Incorrect position of jack bolts

The picture below shows the jack bolt “not in a good position”—it will interfere with the shimming.

by Diana Pereda

Belt Alignment job on Motor & Pump

Belt driven machines are the Rodney Dangerfield of the maintenance industry – “they don’t get no respect!” For example, look at the image below. Belt driven machines do need a little bit more TLC than they currently get. I want to show you two innovations that will greatly improve your maintenance efforts on these highly efficient drives. I also want to show you why the general way in which we work with belt drives is a good example of what keeps reliability unachievable for many.

Belt Alignment

First let me say that there are some individuals/organizations who really understand the value of doing this work right. I am reminded of a gentleman called Gary Burger who wrote a very good article on improving the efficiency of belt drives.  He says that he “expects to get three to five years from a belt that is running 24/7.” And I believe he gets that, and you can too. Keep in mind that this is not a roof fan that will spin forever, this is a working machine that needs sizable horsepower to turn it over.

The reason I say these drives do not get the respect they need is experience. Like many of you, I have seen belts pried off, then a new set pried on. I have seen large sheaves installed with air guns and never checked for runout, so they vibrate in the axial plane. I have seen string used for alignment or a length of angle iron from the steel rack used as a straightedge for alignment. I have seen air guns used to tension a belt so tight that the belt would not defect, even if you walked on it. And belt dressing, which was used a can at a time to try and stop the belt from squealing. All of these are not acceptable if you had planned on doing the job right. The first time.

What is Belt Misalignment?

The number one reason why belts fail prematurely is heat. Heat dries the belt out which leads to cracking and slippage and the end is not far off after that. The heat is from friction caused by misalignment. To correct misalignment, we must correct the offset and angle errors in both the Horizontal and Vertical planes.

Belt Misalignment

The first belt shows angular misalignment in the horizontal plane (toe-out and toe-in). The second belt shows parallel (offset) misalignment in the horizontal and vertical planes. The third belt shows a combination of angular and parallel (offset) misalignment in both planes. This is what we are normally trying to correct.

One of the reasons why it is difficult to correct this misalignment is because you are constantly correcting the alignment as you tension the belt. If you have ever worked with an adjustable motor base that has one central adjusting bolt allowing the motor to pivot as you tighten it, it is a challenge, to say the least. These bases are lightweight, flexible, and cheap. The inexpensiveness is why they are used but there is a hidden cost. You do a lot more maintenance work with this type of base so there is no saving.  The frustration comes from the fact that you are unaware the bases are flexing until it’s too late. This is because it is not something you can see by eye when using a straightedge to align the sheaves. You still must compensate or adjust the alignment as you tension the belt. Download our 5-Step Sheave Pulley Alignment Procedure which provides a simple and effective procedure for sheave pulley alignment of belt-driven equipment. 

Click here to read the entire case study: “It’s About Time We Treat Our Belts & Sheaves With More Respect”

Thank you John Lambert with Benchmark PDM for sharing this educational article with us!

by Diana Pereda

We previously discussed in our series of soft foot, Types of Soft Foot: Part 2 Bent Foot. In this follow-up blog, we will discuss Squishy Foot.

What is squishy foot?

Squishy foot: also known as spring foot, occurs when the gap between the foot and base has already been filled with an excess of shims to correct a soft foot problem.

Proper preparation for a shaft alignment job is essential to success. Inspect the machine components and hardware and ensure the environment is free of any rust, dirt, debris or paint. The above steps are part of the pre-alignment check detailed in our 5-Step Shaft Alignment Procedure and should not be overlooked.

Condition 3: Squishy Foot

  • Caused by compressible material under the feet of the machine.
  • Too many shims can also be the culprit. Try to have four or fewer shims under each foot.
  • Proper cleaning of the environment and use of new crush resistant shims will eliminate this condition.

 

 

Soft Foot - Squishy Figure 3C

Watch our Shaft Alignment Know-How: Soft Foot video to learn about the effects and importance of measuring and correcting Soft Foot when performing shaft alignment.

by Diana Pereda

A few things that should always be inspected during belt PM’s are:

  1. Inspect grooves for V-belts for wear using a sheave gauge following supplier recommendations.
  2. Rusted or pitted sheaves should be replaced. Otherwise, belt damage/wear and premature failure can easily result.
  3. Shiny grooves should not be overlooked and can indicate heavy wear.
  4. Corrosion on the sheave and especially in the grooves will build up and rapidly wear the belt and result in premature failure. Sheaves should be replaced if corrosion is found.
  5. Bent sides can introduce wear and damage.
  6. Replace all belts and never a single belt. Mixing old and new belts results in the load not being shared evenly and could easily lead to damage, premature belt failure and sheave wear.
  7. The same manufacturer should always be used. In other words, do not mix and match belts from different manufacturers on the same drive.
  8. Noisy belts can be identified using a squirt bottle with soapy water. Spray the belt during operation with the soapy water. If the noise level changes, then the belt is part of the problem. It should be inspected for damage, proper tension, etc. If the noise remains, then most likely the belt is not part of the problem.
  9. Ensure that the sheaves are properly aligned. Misalignment will result in premature wear and damage.
Alignment-Belt-Driven-Equipment
Photo courtesy of Brian Franks with JetTech Mechanical LLC

Download our Belt & Chain Storage Best Practices which has some basics things to prevent belt and chain damage and contamination thus maximize parts life and performance.

by Diana Pereda

From a reliability perspective, commissioning a machine requires precision shaft alignment to the correct tolerances and proper documentation. Ideally, these alignments should be performed using a laser system with built-in ANSI alignment tolerances such as the Easy-Laser XT770 and with the ability to generate a detailed graph report of the alignment, both as found and as left. But what if the technician could do a little more than just the shaft alignment, like checking the overall vibration levels of the machine before and after the work? Pre- and post-vibration checks will reassure you and your supervisor or customer that the job was done correctly.

XT280 Measuring Vibration Overalls

A tool such as the Easy-Laser XT280 makes collecting vibration data from assets like pumps, motors, fans and bearings simple and fast. It displays 1×, 2×, and 3× RPM, total level, as well as bearing condition, providing necessary information for the installation and alignment job.

The XT280 interfaces with all Easy-Laser XT alignment systems but can stand alone if connected to a smartphone or tablet using the Easy-Laser XT Alignment App to generate PDF reports with photos of each measurement point to support acceptance checks after installation and alignment.

XT280 Vibration Overall Values

 

by Diana Pereda

We previously discussed types of soft foot in Types of Soft Foot: Part 1 Parallel Air Gap. In this follow-up blog, we will discuss Bent Foot.

What is Bent Foot?

Bent foot: Occurs when a foot of the machine is deflected or in an angle with regard to the base. However, this also applies to when the base is in an angle with respect to the foot.

When a machine has a soft foot condition, the act of tightening the hold-down bolts will put stress on and distort the frame. This will cause the bearings that hold the shaft to misalign internally, which can cause vibration, out-of-roundness in the bearings and stress on the shaft. Minimizing the effect of soft foot will increase your machine’s reliability.

This condition in our soft foot series is a common one.

Condition 2: Bent Foot

  • Caused by one (or more) machine feet that are bent or angled to the mounting surface. Can also be caused by a deflected base.
  • Feet that are not parallel to the surface will stress the machine when tightened down.
  • To correct, re-machine the feet, base or both.
  • Step-shimming is also an acceptable solution when pressed for time.

Soft Foot - Bent Figure 2B

 

Download our Soft Foot Find-and-Fix Infographic which outlines the of types of Soft Foot including causes and corrections.

by Diana Pereda

The Easy-Laser E970 alignment system makes roll parallel alignment accurate and easy to accomplish.  This application requires that the rolls be parallel to each other in term of skew and level.  In addition, and very important to the application, is to make sure the slitters and guides are aligned to each other axially on the rolls.

Sheet Metal Roll Slitter - Pic1

Should they not be aligned, they will cause forces on the guides, causing the product to be affected during the process.  The E970 system was set up so that the laser was exactly parallel and level to the reference slitter roll, a process that took about 10 minutes.  The laser transmitter was then deflected a perfect 90 degrees for a vertical sweeping laser plane that could be projected down the line.

Sheet Metal Roll Slitter - Pic2

The finding was that the guides were off at some places by as much as 3/8″!  Corrections were made live and the appropriate spacers were installed in order to make sure the guides were in perfect alignment with the slitters.

Sheet Metal Roll Slitter - Pic3

The outcome was that the product produced was of a high quality that had not been experienced on the machine before.  A report was generated directly from the Easy-Laser E970 in PDF for documentation.

by Diana Pereda

What is soft foot?

Soft foot is a common term used for machine frame distortion. The distortion is caused when one or more foot of a machine differ in height from the others.

Soft foot can be frustrating and bad for the health of rotating machinery and the sanity of the technician performing the alignment. Soft foot needs to be corrected in order to achieve a good alignment. When attempting to correct soft foot it is helpful to identify the type of soft foot condition(s) present in the machines. This will allow you to more intelligently approach correcting the defect and get you moving on your way to the rest of the alignment.

In this series we will cover the types of soft foot conditions likely to be encountered during any given shaft alignment job.

Condition 1: Parallel Air Gap

  • Caused by one machine leg that is too short or a base that is not coplanar at all four mounting points.
  • Produces a “rocking” effect as the leg that is located diagonally from the “short” leg is also affected.
  • To correct, simply add shims to take up the gap and remove any rocking effect.
  • Correction is usually made at only one foot, or in rare cases, at both diagonally opposed feet.

Soft Foot - Parallel Air Gap Figure 1

 

 

 

Watch our Shaft Alignment Know-How: Soft Foot video to learn about the effects and importance of measuring and correcting Soft Foot when performing shaft alignment.

by Diana Pereda

When a failure occurs, one of two things happen:

  1. A Failure Analysis program kicks in to figure out what truly caused the failure in order to eliminate the condition that caused that specific failure. Or…
  2. The easiest thing to see gets blamed. That “blame game” can be influenced by factors that have nothing to do with that specific failure, like past experiences, mechanical prejudices (preferring one brand over another), personal differences (doubting another’s workmanship), and even possibly looking to sweep the whole problem “under the rug” to distance someone from that blame.

When it comes to the failure of a crankshaft, or any other component of a rotating assembly, alignment is one of the things often brought up, like a “low hanging fruit”. This is why having a proper procedure, such as our 5-Step Shaft Alignment Procedure is so important. Going through each step of that procedure will help spot and eliminate the defects that could cause the equipment to experience that failure. And once the work is completed, the documentation portion becomes a record of how the job was done in order to help with any Failure Analysis.

Let’s take a look at some failure modes and see what could have caused the issue instead of just saying, “must have been a bad alignment.”

High Bearing wear at the front of an engine with Oil Analysis showing Tin, Aluminum, and Copper

Since this is nowhere near the coupling, alignment would be hard to blame, but there are other things to consider when looking for causes. Do the belts have too much tension? Was Soft Foot or Base Deflection overlooked? Has the Harmonic Balancer failed? Has the engine been reconfigured to run faster than originally rated and not have the supporting parts replaced to accommodate that increase in RPM? The bearings are coming apart and the cause must be found. Download an outline of types of Soft Foot including causes and corrections.

High Bearing wear at the front of an engine

High Bearing wear in the middle of an engine with Oil Analysis showing Tin, Aluminum, and Copper

The problem is getting closer to the coupling so it cannot be ruled out, but it would need to be a large amount of misalignment to cause the bending of the shaft and a proper alignment procedure with proper tools and training would help eliminate that. What else would cause this condition? How about web deflection? Are the middle feet of the engine properly mounted and torqued?

High Bearing wear in the middle of an engine

 

High Bearing wear at the rear of an engine with Oil Analysis showing Tin, Aluminum, and Copper

Now we are talking a lot more about the alignment. Since the coupling is right next door, we have to be very aware of what that alignment looks like. How was the equipment aligned before, and what does the report show for an “As Left” condition? Has the equipment shifted or is the base and foundation degrading to the point that it can no longer support the weight and power delivery on this package? Was Thermal Growth calculated correctly and properly compensated for? All of these factors should be addressed with the application of a proper alignment procedure. Download an overview of 4 common thermal growth methods including advantages and disadvantages.

These are just some of the issues that have been discussed when a failure occurs, and in a lot of those cases, alignment got an unfair amount of the blame. If a procedure is in place to perform alignments correctly, and documentation has been properly archived, Failure Analysis should go much smoother to find the actual cause of the failure, instead of just going for the “low hanging fruit”.

by Diana Pereda

Marine propulsion alignment consists of ensuring that all bearings and rotational centerlines are set into a straight line as per the installation requirements. Depending on the vessel size, this means the machine, gearbox, clutch, support bearings, stern tube and struts should all make a straight line when the vessel is at sea. Proper propulsion alignment prevents unnecessary loads to the bores and prevents vibration due to back and forth bending cycles of the propeller shaft due to misalignment.

Ensuring this alignment is correct in dry dock is a physically demanding task!  Ask anyone that has been tasked to perform such measurements and they will probably have stories of climbing in and out of the stern tube and though cramped spots—“Propulsion Alignment Yoga”.

With all the components that will need to be checked and re-checked after corrections, it is imperative that the alignment system be accurate and easy to use. Traditional marine propulsion alignments involve the use of a tight-wire that is stretched down the length of the propulsion line.  While simple in concept, it is not without its woes.  If a component needs to be removed, the line must be broken and reset.  The wire can bounce due to wind and vibration.  Finally, the operator must physically avoid coming in contact with the wire.  In many cases, this is physically impossible and dangerous. It is dangerous because if the user was in a stern tube taking a measurement and the line broke, that high tension wire could seriously injure the person in the stern tube!

Propulsion Alignment Results using the E950

Fortunately, this task is made both safer easier with the Easy-Laser E950B laser marine propulsion alignment system.  The concept is simple: the laser beam replaces the tight wire.  The high accuracy laser sensor replaces the inside micrometer.  The system digitally records the position of the sensor and touch probe with respect to the laser with a high accuracy (0.02mm).  The result is quick and easy measurements of marine propulsion alignment.  After the alignment is finished, the system creates a report for documentation showing that any alignment defects have been eliminated.

by Diana Pereda

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