RCM-2009 Reliability Centered Maintenance Managers' Forum - March 23-26 - Daytona Hilton Ocean Walk Village - Daytona Beach Florida Join or Manage Your Profile Posting Boards Machinery Condition Monitoring and Predictive Maintenance Posts About vibration/alignment/balance Laser Alignment
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A bent shaft is an alignment "issue" although it may not be a part of the alignment process. Mr. Rich Henry, I never knew we butted heads. I don't know you. Thermal are an issue and may be a consideration but the root of the alignment process is aligning the concentric centerlines of the machines in question. All these things are a consideration. YOu can't ignore these issues and assume your alignment job will provide the quality of operation it's suppose to. I don't think there's a point of arguement.
Cordially, Sam Pickens pdmsampickens@gmail.com |
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He is a poster here, involved in precision maintenance practices where he works. Has stated several times in some of his previous post about the importance of thermal growth. I should have added smileys in my previous post. I realize that everyone here understands the importance of issues related to doing a proper alignment job, no matter what we call it. Hopefully no one took my post as trying to butt heads or "stir" up something. I had noticed post before here that had voting polls so I had thrown that in. Didnt mean it literally. This is the hard part about conversations thru "type". Its hard to see the intentions and expressions behind what is written. I appreciate everyone here. Most will never know how much I have been helped by reading and participating some in the topics on this board. Wish you all a blessed day. Mike |
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Yeah; no need for argueing. I like to promote the discipline and that's all. But since so many read this thread I think we must clarify thing the best we can. I try to use the Queen's English and Webster's primary book.
Issues of alignment are such factors of bent shaft and soft foot. They are a part of the process and procedures although not necessarily the method. Soft foot directly effects alignment as it means case distortation which throws the bearing bores out of alignment and possible distorts or 'egg' shapes them. A soft foot check should be a part of the alignment procedure regardless of method. We're attempting to align the concentric centerlines of two shafts. When accomplished an end view will look like one dot or one cross-hair instead of two. So by aligning the concentric centerlines of the bearings we're aligning two imaginary lines that are perfect. I'm not attempting to make two shafts co-linear. The shafts may have run-out or may be bent and not linear at all. Regardless, I think I know the intent of using the term co-linear; it's the same thought as making the bearing centerlines concentric or one in the same. Bent shaft is an alignment issue and part of the process and procedures else you could be aligning machines that are not worthy of aligning and wasting someone's time and money. However, bent shaft, and run-outs aren't a part of the alignment method - only alignment issues. Thermal considerations are a part of all jobs thereby making them an alignment issue but not necessarily a part of the alignment process and not a part of the method. An orderly set of procedures will include asking the question and recording run-outs; it's a part of the procedures but not the method of aligning. Since soft foot directly is part of the process and procedures it is also a part of the method and becomes necessary to makes checks for soft and corrections if it exists out of tolerance. I don't know of any method of alignment that leaves out a soft foot check. As mentioned: language is somewhat of a problem on this thread as so many are on and from different countries and regions. It is a problem here in the USA - like double-jack vs. sledge hammer. Although they are the same tool, someone in one regions of this country may not know what a sledge hammer is. I was in AZ and asked for a sledge hammer and got some funny looks. After staring me down for 15 seconds, the guy asked what a sledge hammer is: I said basically it's a Warren head hammer; he said, "oh, you mean a double-jack". As for Gary Buckles in FL - he is a seasoned vet of maintenance and well versed in the discipline having good experience and knowledgeable both in alignment and vibration. I certainly pay attention to what he says. My 2 cents worth. Cordially, Sam Pickens pdmsampickens@gmail.com |
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If found this on webster.com.
Main Entry: col"¢lin"¢ear Pronunciation: k&-'li-nE-&r, kä- Function: adjective Etymology: International Scientific Vocabulary 1 : lying on or passing through the same straight line 2 : having axes lying end to end in a straight line <collinear antenna elements> By using the term collinear one implies everything is on a straight line. So much for aligning bent shafts if this is included in the common definintion of alignment. I would beg for some variance, because the gravity sag must be considered. Could straight mean straigh in a gravity enviornment.  I hope everyone understands what is desired for an alignment and doesn't take this to serious. Regards, Bill Bill.Foiles@bp.com |
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Bill; an excellent point. Gravity is always with us. A bracket may SAG and the shaft it sits on, made of steel and hanging out 15" from its bearing support and having a 15# coupling hub on it. What about elastivity and recovery from elastivity. The elastic coefficient doesn't really change w/diameter but a stubby shaft has stiffness to consider. A 52 gram indicator will pull a 5/16" rod down considerably at 10".
Cordially, Sam Pickens pdmsampickens@gmail.com |
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I'm clear: alignemt scope is defined only in Quotation and Service Order; could be the system needs many tasks: align, inspections for bearings, balancing, shafts, etc. motor condition, etc. etc. but for me are another tasks. If a customer says: "please solve this vibration problem" then price needs to be changed and is my concern to do every thing needed to solve it, but price reflect it. Regards
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As a professional you must do your client service and by that I mean good service. Often they don't know and that's reflected in the wording of he service order (afterall, if they knew what was wrong and could fix it would you be there?). If they have left something out, then you should point this out to them I think.
Quality of work is #1 regardless of price. If one customer offered you $500.00 do to an alignment job and you took it and think wow I made out good on this one but another offered you $200.00 and you took it unhappily: would you provide less service or substandard quality? So, it's not all about the money, it's about personal integrity. I'm in no way saying anything about you or directing my comments at you - as with this language thing - I'm not even sure of exactly what you're saying. But when you turn in your bill, the customer should have a warm happy feeling because of his/her satisfaction with your quality of work. I know I've made answers on this thread to question I misunderstood and probably went in the wrong direction. I do believe we all must be forgiving and understanding here as basically we are only trying to help one another and promote the discipline. Most questions are short and often without enough information but we try to help anyway, usually; but buy the same token the answers are generally short and no one is trying to write a book on this thread to give free information to someone that in all probility will never be a paying client. If I do soul searching and ask myself what is my agenda and what are my motives; I can say to promote the discipline. It's sure not for income as it does't put money in my pocket that would be worth $5.00/hr. Cordially, Sam Pickens pdmsampickens@gmail.com |
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Sam, what I think is: we need to be clear before to solve a problem, integrity is a problem for both of parts, because that Quote and Service Order must be very very clear.
Some years ago one of my customer called me to balance a heavy motor, during measurement I saw that problem was not balance but a bearing fail, I've asked to change it and a new measuremet showed that vibrations were very low level and not need to balance. My customer said that because I did not balance that motor he did not need to pay me. After 10 months a lot of phone calls and visit to general manager they paid me. After that I define all scope very well in my quote and read every word in my Service Order. To be clear regarding scope of services is not a bad thing. You say alignment? then alignment, not bent shaft, balance, etc. etc...what is wrong about that? |
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We are not is disagreement. Language is a problem regardless - over the Internet or in a local pub or from a PA......surely a PA couldn't foul-up! Now, couple that to some types of people that are willing to take advantage or cheat and .... as you described; a pain in the behind. Yes, it is possible that the PO was written loosely intentionally??! Wouldn't judge that one but there are those will to take advantage if they can.
You described an nightmare and probably many have experienced such. But like the balance job - bent shaft is part of the alignment procedure - you must check for run-outs. It's an issue and part of the process and procedure although not a part of the alignment method as you are aligning perfect lines. Your call-out should carry a minimum of a 4?hr charge or something reasonable. If alignment is a 2 hr job and you travel 1 hr but brought to their attention that the unit is not alignable due to a bent shaft it's their shot to call but you're covered by your minimum or you can always reduce the minimum for PR and get invited back. You're talking business decisions and not technicial issues regarding alignment. So business ethics may not be a part of this post. Cordially, Sam Pickens pdmsampickens@gmail.com |
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Man! I thought that me saying you should check for runout was a pretty uncontroversial thing to say
 Danny |
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Sam, OK, but why not to check cracks or another problems? do you check cracks?, it is a mayor concern about a shaft, could be more important but I've never seen to check that before an alignment task. If you want to be sure about every thing about machine before to align could be that we need to use Vibration collector, alignment instrument, ampermeter, thermometer, ultrasonic analyzer, etc. etc. (could be that we look like Ekeko as you can see in attached file, we say that here when we are full of gadgets for our job). This is my last opinion, best regards....
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One thing about the order of posts here (first post to most recent) is that you get the whole story! Completed an alignment this morning and covered as many bases as possible with time allotted, soft foot and run out. Confirmed alignment success with vib analysis upon completion. Ultimately consumers of our services are concerned with one thing only and that is the life and health of the equipment when weighed against effort (cost) to maintain it's condition. How we deliver that service is as artistic and comprehensive as the person applying the technologies. That's My Nickels Worth,
 Good In = Good Out |
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Do I check for cracks? Every chance I get; of course we're talking about wise cracks, huh? It's amazing what comes on the radar screen.
Cordially, Sam Pickens pdmsampickens@gmail.com |
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If you could, I would like a copy of the list of pre-alignment considerations. THis piece of equiptment is a extruding machine being driven by a 200-250 hp dc motor. The original motor burned up (armature windings let go), so this motor was sent out for repair. While we where waiting for its arrival, I was asked to see if there was any prep work that could be done ( motor was supposed to show up in a few hrs). I went down to equiptment , and noticed that the original shims that where under the motor feet, where corroded and one was missing. After blast cleaning the shims, the pitting was bad so we decided to make some new shim plates. At this time, we did not have a shim kit in stock for this size of motor. After makeing new shims, I later found out that the motor would not be arriveing that days. I had the parts dept rush order a shim kit. The base that the motor sits on, was also rusty. We cleaned it up as best as we could. I did notice that with the new shims (plates) that where made, when set in place on the mounting base, there was some wobble to them. It is very possiable that when the replacement motor was installed, that a soft foot condition existed. Again, this was installed on a different shift, and this equiptment was a High priority. Down time was hurting. After it was installed and running is when the vibration was noticed (by touch and then verified by the vibration tech). If my memory is correct, vibration tech stated that it was a horizontal movement that was detected ( viewiing from ODE of motor looking forward, the movemet was to the right) I had ask him about unbalance, and he stated the the movment would be in a direction toward the ODE of motor. Equipment: Commtest Vb7 collector |
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I aggree 100%. Why have to do the job multiple times when if done right the first time is all that was needed.. Equipment: Commtest Vb7 collector |
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Pre-alignment considerations: generally one machine is movable and the other fixed. So, begin with the fixed machine - free of soft foot and stresses (piping, etc.). Ensure anchor bolts are tight and it's sitting at proper elevation and/or a height that will allowing shimming up of the motor, turbine, etc. 2.) check coupling or inspect. 3.) Check run-outs and record. 4.) Check soft foot and correct if necessary [although rare, check electrical connection to ensure it hasn't been hard-plumbed or induced stresses from ??? ducting??]. With all correctons/checks made you should be ready to select the approiate method to do the alignment task. I have a set of procedures if you would like a copy. Something that is also on my check list is: axial positioning spacer used? and if checked yes the last step of the procedure is - remove positioning spacer (it's easy to forget in a closed-shrouded coupling (falk).
Cordially, Sam Pickens pdmsampickens@gmail.com |
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Sam, If you don't mind, I would like to see a copy of your check list. Thanks Equipment: Commtest Vb7 collector |
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I used the term 'check list' but it is generic and basically automatic: you don't just walk up to a machine and start aligning it without making certain checks. I don't have a check list but an alignment procedure chart and alignment tolerance chart. So, the removing the axial position spacer is in the procedure chart.
Cordially, Sam Pickens pdmsampickens@gmail.com |
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XRacer,
I will get you a copy of the pre alignment considerations for you to use if you like. You mention that this is an extruder...if there is some misalignment of the extruder barrel relative to the output gear rotational center, this would show up as a higher than normal vibration (could be exciting a natural frequency somewhere) and will likely be loading the motor harder than it normally would be. The barrel alignment can be easily set so the screw will slide into the barrel by hand. If this is not happening the barrel is likely misaligned and you are trying to "rotate a telephone pole in a water slide". Best Regards, Rich |
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