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MarkL

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Reply with quote  #16 
Mark you beat me to it, I was going to say I've seen similar issue on animal feed mills, they have multiple hammers chipping material before feeding the die, And unbalance is always an issue and they won't rebalance at the frequency required(a ridiculous frequency in comparison to mosy things)

Some I've encountered have a total loss lubrication system when it comes to the die end, and they rely on a flushing action of the grease through the mill. Most I've encountered are Buhler and Andritz.

What we have done is just monitor them closely and more or less "live with it"

marksl

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Reply with quote  #17 
Quote:
Originally Posted by MarkL
Mark you beat me to it, I was going to say I've seen similar issue on animal feed mills, they have multiple hammers chipping material before feeding the die, And unbalance is always an issue and they won't rebalance at the frequency required(a ridiculous frequency in comparison to mosy things) Some I've encountered have a total loss lubrication system when it comes to the die end, and they rely on a flushing action of the grease through the mill. Most I've encountered are Buhler and Andritz. What we have done is just monitor them closely and more or less "live with it"


Great Mark's think alike lol
Ralph Stewart

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Reply with quote  #18 
Quote:
Markl quote:
they won't rebalance at the frequency required(a ridiculous frequency in comparison to mosy things)


Markl,

If 1x RPM is not the balancing frequency? What is the balancing frequency that warrants calling it "a ridiculous frequency"?

Strange!!!!!!!!!!

Thanks,
Ralph

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Walt Strong

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Reply with quote  #19 
I am guessing that in this case "balancing frequency" indicates the time interval that the machine rotor needs to be rebalanced.

Walt
Ralph Stewart

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Reply with quote  #20 
You may be correct Walt.

I guess the word "they", refers to company personnel's decisions, rather than referring to "they" as being this type of woodchip rotor, and the "frequency" means, "run as long as we can before balancing" [smile]

Sorry, my BAD. [biggrin]

Thanks,
Ralph

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MarkL

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Reply with quote  #21 
Quote:
Originally Posted by Ralph Stewart


Markl,

If 1x RPM is not the balancing frequency? What is the balancing frequency that warrants calling it "a ridiculous frequency"?

Strange!!!!!!!!!!

Thanks,
Ralph


Ralph when I say frequency I mean as to how often, not the 1x.
From what I have seen those machines would need to be balanced once a month heck even once every 2 weeks!! and no one is going to pay for that.

OLi

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Reply with quote  #22 
Good they just bought balancing equip. then :-) maybe they have the same idea.
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Dan Timberlake

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Reply with quote  #23 
So is the "wear" outer race > housing, or internal rollers>races ?

RPM and bearing size and grease specs ?
marksl

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Reply with quote  #24 
Quote:
Originally Posted by Dan Timberlake
So is the "wear" outer race > housing, or internal rollers>races ?

RPM and bearing size and grease specs ?


For the feed mills that I monitor;
speed is 3000rpm
wear is between housing and bearing OD in both side of the mill and motor bearings
Mill bearings are 2314
lubrication is grease
Ralph Stewart

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Reply with quote  #25 
Sorry Markl.

My mind was stuck on 1x balance frequency rather than management's balancing frequency. [crazy]

Thanks and Have a Great Day,
Ralph

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MarkL

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Reply with quote  #26 
No Problem Ralph,
I can see where the misunderstanding could happen I type ina stream of convoys was as I think :-).

RE the speed and wear between the outer race and housing sounds familiar I’ve seen fretting corrosion in some of them.
RRS_Dave

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Reply with quote  #27 
Oli,
If that tin can thingy has a clear button on top that you can see a flashing red light once in a while telling you it is working, and a row of dip switches to set emptying frequency, I'll tell you that I am not in the least impressed with the reliability of these particular canisters. None of these canisters can overcome any type restriction in the lubrication pathway, and this includes a 1/4" pipe that many of them are sitting on top of. I have two customers that use these grease canisters in a lot of places, and I have gotten them both to start drawing a line on them where the piston is (clear bodies you can see the piston) along with the date, The next time they come around to observe them, they reference the line, make a judgement as to where the piston should be based on current date and what the canister replenishment frequency is set at, and then to go on if everything is cool, or hook a grease gun up to the line and see if they can manually grease them and shove out of the pathway any hardened grease or anything that may be blocking it. In the case of many bearings, when the put them in, very few people will turn the outer race to position one of the holes right under the canister. In not doing so, they force the canister to push grease around the groove till it finds a hole. These particular canisters I'm speaking of only pump up around 50 PSI, and that's not much to shove any viscous grease (anything over 100 is tough for them).
I'd be sure these greasers are actually getting enough grease to the bearings. This is probably one of the applications I'd like to see grease coming out around the labyrinths (If that's the kind of seal they have) as long as it's not high speed. One of my customers that use these have some rather large double roller bearings running at fairly high speed causing the dn number to be right on the line of grease/oil. The bearings run hot, and I've tried to convince them to change over to oil on one machine just to try it. They'd rather replace them twice a year than do that. They did however, replace one set of them with Coopers (also a recommendation) because of their ease of replacement. I didn't stress the fact that the Coopers will take a ton of abuse before they need replaced (and they stuck these same canisters on the Coopers). We'll see how things go, but I certainly am not sold on these metal canister thingy s to solve all lube problems.

D
OLi

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Reply with quote  #28 
I fully agree I really doubt those systems too. Problem is that the humans are sometimes more reliable to be unreliable, tin cans at least works sometimes. I have cases where large motors mill wide was neglected for several grease routes including summer vacation and that is here nearby where things should be "perfect" and ISO 9000 to the letter. These large motors had intermittent bearings fail for several years after that. They now have a tag on each zerk and log all greasing.... This current plant is a bit east of us where conditions may be better or worse who really knows. I also seen outsourced greasing of hammer mills here where the 5-10Kg canister at the central point was empty and also when testing it "on a regular basis" nobody verified flow down the pit to the bearings just to the floor joint so still bearings were not greased. Because it was so messy.... It was lucky that it was just when we measured the bearings like once every 5 years randomly and it was surprisingly no serious damage as greasing was restored pdq. They now went bust but more related to oil price I think. So greasing is very important and may cost large sums if not done properly and it is seriously irritating when trying to improve maintenance when the job is done bad or not at all.
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RustyCas

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Reply with quote  #29 
The hammer mill that I balance a couple of times a year uses double-row roller bearings at each end.  Bearing clearances open up pretty quickly.  We do a lift check to determine the total clearance, then do a tops-off ring-to-roller check with a feeler gauge to determine the bearing internal clearance.  The difference is the clearance between the housing and bearing O.D. and it can be fairly large.  I assume the bearing outer race is a much harder material than the cast housing, and the high imbalance just beats the housing out.  Have told them a number of times over the years to always replace the bearings as a "unit" but they still sometimes only replace the bearing, so we get a so-so balance done, and they have to change the housings (later), and then we rebalance. 

So OLi, if your mill is anything like the hammer mills that the rest of us see, it's just going to beat the snot out of any bearing you put in there.  Trying to make it better given the current design may just be "putting lipstick on a pig."  I am amazed how often manufacturers of expensive machines just seem to be clueless about practical design considerations, or design the machine to run well only under the best of circumstances.

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OLi

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Reply with quote  #30 
Yes designers are the best of people, keeping us busy :-)
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