Flatness Measurement in High Temperature Environments

July 3, 2014

A microchip manufacturer in the United States utilizes circular aluminum plates approximately 2 to 3 feet in diameter in the manufacturing process. These plates are heated from ambient temperature to +400 degrees F. The manufacturer wanted to ascertain if any distortion would exist across the surface of these plates when hot, and if any differences in the flatness of the paste would occur between the cold and hot condition of the plates.

To measure this accurately, a ROTALIGN ULTRA iS with LEVALIGN EXPERT flatness option was used. The customer fabricated a steel jig to go over the aluminum plate. The jig was insulated from the bottom (see Figure 1.)

Fig 1 Steel Fixture

Fig. 1: Steel fixture with insulation placed over Circular Aluminum plates

9mm holes +0.002″ were pre-drilled through the steel jig to allow the Levalign plunger bracket to fit freely yet snugly through the holes and make contact with the aluminum plate underneath. A standard circular measurement pattern was selected. The ROTALIGN ULTRA iS sensor was mounted on the plunger bracket to obtain the readings (see Figure 2.)

Fig2-Sensalign-on-plunger-bracket

Fig. 2: ROTALIGN ULTRA iS sensor mounted on LEVALIGN flatness plunger bracket through holes in steel jig

All readings were repeated to within 0.0001″ and fell within 0.0001” of what the customer thought they were. A thermal expansion of 0.020″ was measured from hot to cold, although the plate remained flat to ±0.002”. Figure 3 shows the measurements being performed.

Fig3-Levalign-measurement

Fig. 3: LEVALIGN EXPERT on left and ROTALIGN ULTRA iS sensor during measurements

Although the original method used to perform these measurements was not disclosed to us, the customer did tell us that the ROTALIGN ULTRA iS with LEVALIGN EXPERT saved them many hours in the measurement process, and although no dollar savings from this process were mentioned, the customer immediately purchased the ROTALIGN ULTRA iS with LEVALIGN EXPERT , without hesitation.

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Contamination Impacts Equipment Reliability

July 1, 2014

Ingression can be defined as going in or entering, a right or permission to enter, or a means or place of entering. It is important to understand, recognize, detect and reduce the effects of particle ingression. Doing so will have a very positive effect on your maintenance and reliability efforts.

Dirt is often the root cause leading to bearing damage and reduced equipment reliability. If not monitored correctly, ingression can lead to unexpected failures resulting in high maintenance and inventory costs.

When measured in the Moh’s Hardness scale, dirt is typically more abrasive than the bearing material. This leads to pitting and other damage to the bearing that reduces the life of the equipment. It’s really quite simple: under great load something has to give and it’s usually the bearings, gears, pump impellers, etc. Our goal should be to remove contaminants from the lubricant to our target cleanliness before placing it in our equipment. Doing so will increase our equipment reliability.

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How to shim a vertical flange-mounted motor with ROTALIGN ULTRA

June 26, 2014

If you have a vertical flange-mounted motor and need to shim it to correct angularity, our laser systems provide the following handy options to accomplish this:

Rotalign Ultra Flange Shimming

How to decide which option to use?

MINUS: If you have plenty of shims already there, you can select this option minimize the amount of shims used, since the correction will be accomplished by removing (subtracting) shims.

PLUS: if you have no shims between the motor flange and support flange to begin with, you can select this option to effect the correction by only adding shims.

PLUS-MINUS: With this option, exactly half of your corrections will be positive (adding shims) and half will be negative (removing shims). This option is very handy if your pump impeller hangs from the thrust bearing in the motor and you do not want to change the pump shaft’s axial position. The plus-minus option makes your pivot point the shaft centerline itself, so that the correction will have no z-axis effect on the shaft from shimming at all. This also minimizes the absolute amount of shimming needed.

ZERO-PLUS: This option means all positive shimming but forces one bolt location to be zero (no correction). This is very handy when the bolt circle diameter is the same as flange diameter, or you already have some shims between the flanges to start with, and want to minimize the amount of shimming needed.

ZERO-MINUS: This solution is similar to ZERO-PLUS but in the negative direction, meaning all corrections call for removing shims, with one bolt position at zero correction. This is handy if you have lots of shims already between the flanges and want to reduce these while minimizing the corrections needed.

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Location! Location! Location! Vibration sensor placement is crucial.

June 24, 2014

For the highest confidence level possible while doing predictive vibration analysis work, location and placement of your sensor are crucially important to you. However, sensor placement is sometimes a trade-off between time, safety, and precision.

Most equipment is mounted with the shaft oriented horizontally to the ground and the analyst must decide whether to take a radial horizontal measurement, radial vertical measurement, a shaft axial measurement, or some combination of the three. If the analyst has the time, there is good reason to take all three positions. When it comes to analysis, an analyst can always choose not to view data he or she has, but can never choose to view data he or she did not collect.

Where should I place my sensor? The answer to this question should come from a focused consideration of what each possible position offers to the overall analysis effort. The fundamental consideration in placing your sensor is that the vibration signal from the component or components of interest should take the path of least resistance to the sensor. This should be coupled with thought given to how every likely defect frequency presents itself relative to direction.

Many fault diagnoses are determined, or the level of confidence enhanced, by relating one locations result to another. For example, a high 1× vibration in the horizontal direction on a direct drive center hung rotor could mean a lot of things, if taken by itself. But if this information is coupled with the additional hypothetical data below:

  1. The axial vibration is also high: then possible misalignment or bent shaft become likelier.
  2. The axial is low, but the vertical is 1-½ times as high as the horizontal: Now looseness is probable.
  3. The axial is low, and the vertical is ½ of the horizontal: probable unbalance.
  4.  The axial and vertical are both very low relative to the horizontal: In fact, the horizontal is 75 to 100 times the axial and vertical! Almost unquestionably there is a resonance problem.

In all of the above scenarios a phase and visual inspection are required to deliver a truly confident diagnosis, but the directional aspect of data analysis is clearly shown.

Trending puts still further demands on the analyst by requiring each successive measurement to be taken in exactly the same place as before, to the extent possible. For parameters to be reliably trendable, operating states and data collection states need to be the same from measurement to measurement.

A real danger for the analyst using mobile data collectors lies in the monotonous repetition of placing a sensor hundreds of times in a day of data gathering, and becoming careless when making that next placement. If feasible, routes should be kept small enough to help avoid the human factor. It’s too easy to day dream while collecting data. A route under 200 points helps keep the monotony away. The analyst should focus on both safety and data collection precision throughout each route. Happy defect hunting!

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Belts require certain best practice to ensure reliability

June 19, 2014

Proper location is very important when collecting vibration measurements on a belt system. If possible, one reading should be taken in line with the sheaves and one reading perpendicular to them on each bearing. Vibration data resolution should be taken into account so that proper separation between belt and driver frequencies can be obtained. Care should be taken to ensure proper belt alignment as well. A laser pulley alignment tool provides the most efficient means to properly align belts. Another issue is how the belts are installed. Was the equipment loosened and the belt put on properly? Were the belts instead rolled on by force, creating potential issues? Have you ever seen a Vee belt running upside down? This is usually caused by the cording in the back of the belt being broken often caused by rolling on the belts. Are sheave gauges being used to check the sheaves for wear? In some cases the cost of a belt is more than the cost of a new sheave. This is just some of the things to consider for proper installation, maintenance and identification of belt related problems.

Don’t just assume that belts are simple and do not require best practice actions for proper operation.

More about Cost-effective Sheave Maintenance

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You are the champion! Don’t let the vibration analysis or reliability program become a “flavor of the month” effort.

June 17, 2014

The scenario: You have just been informed that a corporate reliability initiative has begun. Your new assignment is to implement a vibration analysis program. You are disconcerted, because you are not sure how to implement this new assignment or where to seek help. Many organizations implement a reliability initiative because their competition has already done so or management has become convinced of the financial value that can be gained from it. Unfortunately, as with most things in life, the devil is always in the details.

Company culture plays a critical role in the successful implementation of a reliability program. This shouldn’t be underestimated. Some companies implement program after program, each with the best of intentions. The objectives are always to increase operating efficiencies, achieve cost reductions, capacity improvements, shrink required manpower, etc. Many of these efforts fail after a few months because the program is replaced by something new, key management individuals did not support it, inadequate funding was provided, proper awareness not instilled and many other reasons. The new initiative falls into an abyss and is quickly forgotten. Most seasoned employees who work in these organizations have seen this happen time after time over their careers.

Many employees and managers thus adopt a “wait and see” approach. This trait is learned after years of seeing efforts start and quickly fail. Why join the “flavor of the month” club and devote focus to something that will soon be replaced? It requires less energy to wait and see if the new program will remain a company priority and become successful. The financial value to your business is clear, but will only be realized if the program is correctly implemented and sustained. Senior management has to ensure that everyone understands this effort is not a passing fad. Key signs of support must be given with results-driven implementation.

Don’t let the vibration analysis program and other reliability efforts become a “flavor of the month” effort. Become the champion that promotes the value of these efforts and helps to ensure the results are implemented. Doing so can reap great rewards for yourself and pay great dividends for your company. Seek support and advice from technology vendors, co-workers and the many resources available. You are not alone! Many individuals have been where you are now or faced the same challenges within their organization.

The road to success can be long and difficult to traverse. However, with proper implementation, persistence and senior management support you can get there. Persevere!

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