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Grout and Machine Vibration

09/08/2008 10:55 PM

I have a 25,000 lb machine setting on a base of severly deterioated Embeco grout.

What is the general opinion of grout properties in way of dampening vibration?

To what degree can grouting influence or dampen machine vibration?

The machine is a 6 stage IR Centac. 4 stage at one end, motor in the middle ,and a two stage booster at the other end.

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#1

Re: Grout and Machine Vibration

09/09/2008 1:06 AM

Chockfast.

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#2

Re: Grout and Machine Vibration

09/09/2008 1:36 AM

If the foundation has problems, for sure your machine will get higher vibration. Taking the vibration for the foundation in a good situation, the values should be less than 1 mm/s.

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#3

Re: Grout and Machine Vibration

09/10/2008 4:58 AM

An answer you will not like:

Foundation integrity is key to good machinery installation. You should remove the machine and hire a foundation repair company specialist. There are specialists in this. I teach a class of the importance of foundation design and grout for machinery so this is near to my heart.

They will break out all the old grout, chip off old concrete that is deteriorated, oily, fix rusted corroded re-bar (re-bar swells with corrosion and breaks out the surrounding concrete), and basically start over.

Most foundations for machinery need to be 3.5 - 5 x the mass of the machine by weight. The real mount of your machine is the total foundation. Grout, is a liquid shim to assure 100% contact of the skid base to the foundation.

Epoxy grout is even better and it works in tension and compression as a 'glue'. Anchors need to be long and only attached to the foundation for the first 10% near their bottom, and that bottom point needs to be varying depths of 70 ~ 80% of the full depth of the foundation. This is to have maximum stretch, since bolt stretch is what 'fastens' things tightly. The anchor bottom points should not all be in the same plane which causing a stress concentration 'tension' point on the concrete in a straight line. Use grease or sleeves on the 90% of the top of the anchors to prevent concrete and grout from attaching to them.

Then the boys level the skid (to within 1.5 mm of parallel on every machinery foot plate) on a newly prepared intentionally rough surface concrete foundation. Your skid bottom should be dry, free of oil, and have an anchor profile (like sand blasted) and then they pour the new grout, cure, and tight the anchors.

The goal is to have the live loads and dead loads of the machine transfer efficiently into the core (the real core) of the foundation and take benefit of the total additional mass.

There is no other easy simple fix. Get a budget, schedule a month, and do it right. Anything short of that and you will be referring to this post 6 months from now and doing it this way anyway.

Cheers

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#4

Re: Grout and Machine Vibration

09/10/2008 5:24 AM

To install a highly vibrating machine , older method is to make elaborate machine foundation , which involves digging up the floor , filling it up with sand , wood , etc in definite proportion to dampen the vibration of the machine . To do this one needs to first analyse the frequencies of vibration given out by the machine and then try to eliminate them by prescribed methods of foundation . Adding a heavy inertia base plate is also part of the menu and this is indeed a specialist's job .

Modern method is to make very little foundation and to instal the machines on Shock & Vibration isolators and dampers .This gives liberty to shift the machine as and when necessary without hassles and gives a clean appearance . Vibration isolators are very important because these components cut off vibration of one machine being transmitted to another . When there are many machines installed in the same shop floor ,without vibration isolators all the machines will start dancing as soon as one machine is started . Presumably precision work is not possible in such a situation .

Therefore installing the vibrating machines with proper shock & vibration isolators and dampers with minimum of floor foundation is advisable

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#5

Re: Grout and Machine Vibration

09/10/2008 7:43 AM

The foundation of machine is designed to take care of damping the vibrations and also take dynamic loads induced by many external sources. Grout under the machine is just to fill up the gap between foundation and the machine which is placed on steel pads on foundation and grout in my opinion plays no important role.

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#6
In reply to #3

Re: Grout and Machine Vibration

09/10/2008 8:35 AM

Excellent arguments!

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Commentator

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#7

Re: Grout and Machine Vibration

09/10/2008 10:08 AM

I recommend that you get a copy of The Grouting Hand Book by Don Harrison published by Gulf Publishing. ISBN 0-88415-887-X.

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#8

Re: Grout and Machine Vibration

09/10/2008 10:32 AM

The Prof hit the nail on the head in my oppinion.

Chockfast is made by Phil. Resins, you'll find no better for this application.

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#9
In reply to #3

Re: Grout and Machine Vibration

09/10/2008 10:25 PM

GA - An answer I do like, clear, accurate and concise

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#10

Re: Grout and Machine Vibration

09/11/2008 3:30 AM

dear,

1.during running of machines, dynamic loads are acting over concrete or foundation,so dynamic load balancing is very important to keep M/C in stable position,pedustal or fram of M/C is to be grouted,therefore M/C can sustain the dynamic load and alignment shoudnot disturbe,in other word centre of gravity of M/C is to be found that where it is,accordingly we may grout at certain level,

conclusion:- our main view is that vibration of M/C is minimise

thanks

R.C.MANDAL

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#11
In reply to #8

Re: Grout and Machine Vibration

09/11/2008 1:12 PM

Ya and mono-plastic cement for anchor bolt retention...

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#12
In reply to #5

Re: Grout and Machine Vibration

09/12/2008 3:28 AM

Hi Karan

Respectfully, your reply about grout playing no real important role may be inaccurate. Grout is one of THEE most important ingredients in a total installation. In fact, I rate it as a focus of study when evaluating high risk installations. Grout is the 'conduit' of transfer for live and dead loads to the mass of the main foundation.

Something to think about in any case. I might be wrong.

Cheers, and thanks for posting an answer. Please continue.

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