Before you do anything:

How often is maintenance done on these screens?

If you have bad bearings that will effect everything.

It may be a simple as cleaning the buildup of paper on the screen decks as the weight of the material not screened off of the decks that is stuck to the screen decks will throw everything off. ■

Greetings and salutations Jathayde,

It really sounds as if your screens have a balance problem from the build up of paper waste.

If you have access to a pressure washer or a steam jenny to clean the screens that will help a lot anf go a long way toreducing your poor screening problems as the paper dust will act like glue.

My friend george baker will be able to expand on this more I am sure.

Paper was a lot simpler when all we had to contend with was the triple wall paper sack and sewn bags- the plastic of course is used to reduce weight and is used to seal the top of it with a pull string opener-much harder to recycle from the waste stream. ■

Greeting and salutations athayde,

your screens can only go so fast and so stroke only so far within its capacity and size. I would not recommend trying to improve it unless you contact the manufacturer of the screen as you will have a mess on your hands from frame damage and springs breaking etc.

It honestly sounds like buildup of paper waste is slowing it down so a good cleaning is most likely what you need-dont forget the paper dust is like a glue but with a static charge just like using a paper shredder with all the dust it creates and the resultant charges of electricity. ■

Greetings and salutations,

Before I forget it- have you checked the belt tension on the electric motor to the exciter-better yet do you have a v-belt tension gauge that most likely is the problem- ran into that a while back with a friends screener for milk powder in New Zealand.

If the V belts are over tightened it will affect the throw weight energy etc.

If your V belts have little or no slack in all three screens that is the culprit.

If you do not have one: please purchase a V belt tension gauge for a motor car (I am assuming you use a B sized V belt for transmission of power to the screens) car tool supply house such as the local Snap On tool dealer as this will give you the correct tension for you V belts all the time every time

and prevent overtightening which will have a negative effect the screens performance and ruin bearings on the electric motor and screener prematurely.

If there is no flex at all in the belts driving the exciter they are to tight period and I am willing to bet that there is a lot of slack/loose fit on the shaft end of the old elelectric motor bearing -pleaee check the motor shaft for a loose fit sloppy bearing if you have not shipped it out for rebuild.

lzaharis ■

Hello jathayde:

1. I would like to see the pics.

2. Old machine or new?

3. Opgs in wirecloth please?

4. Measure the stroke length and advise pls.

5. You said ..... recently revised in one post....what does that mean? To me.....it means something changed....and that usually helps us define a problem....or Most times anyways.

Looks like me buddy Izaharis is taking xl care of you so far.

PS: Do you have your offset counterweights set to FULL OFFSET or most aggressive stroke and what angle are you stroking at. If too vertical,,,not much movement.

Thanks for your question. George ■

Hi again: Hmmmmmmm....now were having fun.

YOu words tell me you have some circular stroke and some ellipse stroke config. THIS is not good.

And this machine, my understanding is a linear action screen.

Strokes should be same all around, if not you basically have a machine running in an unbalance state....for a reason, yet to be determined.

All weights on all exciters must be the exact same offset setting or all heck will break loose.

The machine is vibrating clear all the way around I assume? No buildup of material packed around the vibrating body restricting vibration?

I would love to see the STROKE CHECK....if you can put it on paper and email. If you can't send thru this forum site.....send to my PRIVATE EMAIL.....so we can dianose it. ■

I´m new in this field, so I wish to know what to look first on a vibrating screen efficiency diagnosis.

Actually we have a set of 3 VS´s showing malfunction, or say ,movement is not linear as it should be expected.

Screens are powered by a counterweighted motor .

What can be done to improve linear forward movement?

Just counterweight set?

Springs stiffness would count? ( rear different of back springs?)

Using frequency inverters to adjust freq.?

Moving motor from original position?

Thanks in advance for any clue and it´s possible effects.

Athayde

Check the comissioning report to see if teh screen has ever worked correctly and there is no design problem.

Most of this kind of problems is the frequency problem - about 80% of teh screen I have seen in the field. Do the impact test on the screen and determine the locations of natural frequencies - then move the running speed to the good operating window and increase the stroke to get the process right ( normally you should not go above 5g unless you get OK from the screen manufacturer). Springs isolate the screen and changing them will not give you the required outcome.

You can change the inclination of the screen by using wedges(keep the springs vertical) - that would increase the speed of the material on the deck. ■

Improvement of linear motion: This motion is a function of the placement of the motors on the screen box.

If the motion is in fact not LINEAR, then please describe what you think it looks like or is. STROKE CHECK card would be great for diagnosis.

Improvement to forward motion: The motors could be installed in the wrong location to effect proper linear travel down the screen length. Happens fairly frequently actually.

Counterweight set: will only effect aggressiveness of stroke. Try full offset to see if you get more movement down the screen length. Theoretically this should not solve the problem.

Frequency inverters: for variably changing speed on the fly is a nice PERK but, SHOULD not be necessary. Basically you are screening at a pre-defined aperture or opening and should not need this for a vibrating screen. INverters would nicely on a vibrating feeder going to a CRUSHER BUT, not so much here.

POSITIONING of the motors is VERY CRITICAL. Recheck & advise.

VSMA states and I agree completely we need 3 things to screen properly and efficiently.....SPEED STROKE AND SLOPE all three not 1 or 2 must be setup properly to work properly.

George Moderator ■

I have some questions...

1) has there been any modifications (specifically weight added or subtracted) to the equipment since it was originally shipped?

2) does it have one or two (or more) shafts?

3) where are the shafts? above, below, or through.

4) is the vibratory eccentric mounted directly to the screen or does the force travel through springs? ■

Dear Sirs, we understand that screening efficiency depend on Speed, Stroke and Slope, so, would you recommend to measure some of these variabes. In other words, some recommendations for typical or suggested instrumentation for vibrating screen application ??

BR.,

Gabriel Ortiz ■

Ok the tried method that Tyler uses for designing

a screen for a product is to fill a big water pail with the

material to be screened and lift it up to waist level and dump it

out in one movement determine the angle of repose for the

product to be screened and presto (they say they know the

needed angle of the screen in question)-drives me up the wall

when they do that because it is not necessarily valid due to

overloading the screen deck etc.

The screen needed depends entirely on the

product/ screeniing wet or dry sizing/scalping/ final size

and the big one desired tonnage per hour over the primary

screen deck. ■

Hello Gabriel: Some general rules of thumbs for screening at different openings and their respective SPEED, STROKE, SLOPE recommendations according to VSMA and others.

EXAMPLE:

1) 1-3" CLEAR OPENINGS:

3/8" STROKE, 840RPM SPEED, 20 DEG SLOPE

2) 1/2" CLEAR OPENINGS:

5/16" STROKE, 900 RPM, 20 DEG SLOPE

3) 1/4" CLEAR OPENINGS:

1/4" STROKE 1050 RPM, 20 DEG SLOPE

4) 3/16" CLEAR OPENINGS:

3/16" STROKE 1200-1400 RPM, 20-25 SLOPE

Smaller openings like TERTIARY OR QUANTINARY screening jobs use general rule of thumbs....smaller STROKES, faster RPMS, STEEPER ANGLES.

These above here are CIRCLE THROW INCLINED GRAVITY MACHINES.

When we get smaller we can see STROKES OF 1/32" AT 2400rpms and 33-36 degree SLOPE angle.

we can see machines with electromagnetic vibrations operating at a small VPM or vibration per minute, pulling UP say 1/32" stroke length , running at 1800 or 3600 VPM or vibrations per minute that will do 100mesh to 500 mesh OPENING splits.

CHEK OUT FOR VSMA manual for even more details on assumptive setups.

you can troubleshoot or check STROKE with stroke check card, you can check RPM with tachometer, and SLOPE with protractor to see where your at...and decide what to adjust.

George Baker MODERATOR ■

Dear members: At times it is a chore to add a digital pic to this forum as part of your reply.

But, all you have to do is simple. RIGHT click your picture, then click OPEN WITH TAB, pic a photo editor, LIKE MG PHOTO suite, or

MICROSOFT office manager.

THEN, just CLICK ON, PICTURE tab, then click on RESIZE, and click decrease pic size arrow til pic size shows UNDER 500 pixels....save all.

Now when you add by BROWSE button here........BOOM!!! it is under 500 pixels and it will show right inside this posting for all to see.

PHOTO editors....lots of others also but, try these:

WINDOWS Picture and Fax Viewer

MICROSOFT OFFICE Picture Manager

Attachments

6x16 trackmounted screen (JPG)

■

Dear friend,

Instead of trying to "invent the wheel", you should understand that your unit is a mono-frequency vibrating screen. It will clogg on difficult to screen material such as your application. I suggest you consider the multi-frequency vibrating screen by Kroosh Technologies. It has a no-blinding of the mesh guarantee!

Although it sounds commercialized and I'm not objective, but it is a cutting-edge technology that is dedicated to cases like yours. As always, I'm surprised at the well experienced gentelmans in the forum that do not mention the Kroosh technology as a solution...

You can drop me an email or give me a call. I have no doubt, we can offer you the ultimate solution for uninterrupted continuous process, using our screening technology. (you'll probably be able to go finer with your screening process and increase feed rate!)

Best Regards, ■

Yochi

I think the wheel has not been really invented yet - I design the screens and spend time in the mines trouble shuting problems often with vibrating screens. Mono frequency screens very often are not "mono" and the problem starts when someone tries to play with a frequency controller to "improve production". Screens that are more than 2.4 m wide in heavy mining usually cause some problems when not properly maintained - which is very often the case. Screen selection is based on screen reliability and more often then not on price. Your screens are very good for specific applications but I have not seen any of them in heavy mining applications and I think I never will. ■

I realy appreciate your work. I just wanted to introduce my work and the fact that no one in the bulk forum recommend on our technology that can do those difficult to screen task. Please do not throw mud at my face, take a look at the link below for 200 MT per our of 20% humid phosphate being screened on 15mm, leaving half a screen without material, using a Kroosh ULS 3.5X1.25 which has a total of 4 square meters of screening area.

http://www.youtube.com/watch?v=KAZLmtyaSYs

I invite you to cooperate with us in your project. If you are interested, please drop me a e-mail: mandil@kroosh.com

Best Regards, ■

Yochi

I am not throwing mud in your face. Your product represents a niche in the market. 60g acceleration has many applications - screening compost would be something that comes to my mind and the market is huge - basically every council would need a screen but you have to go to them show what you can do and you need for it a good marketing/sales/engineering department. I have seen many salesmen coming to a mine and they can answer almost none of technical questions, "I will come back to you answer is a standard". ■

Dear Yochi: Not everyone in the world has heard of your company and any brand names mentioned here-in are not for the intent of selling their machines.

The purpose of this forum is to share information:

If you have the solution please give the answer here in a simple explanation....so all forum participants can have the benefit of the answer.

Asking people to drop you an email or give you a call directly and trying to SELL a machine ...is definitely NOT the purpose of this forum. Non of our members gain knowledge of your "special" technology.

We would appreciate your co-operation, in this regard.

With respect, George Baker Moderator ■