Tom Gardner still here?

Na, he gave up and sent all the manufacturing to China.

I'm sure he'll be along shortly.

karl

How can I help?

Tom Gardner fired this volley in news:wIOdnXOEeqqlzRvPnZ2dnUVZ snipped-for-privacy@giganews.com:

Tom,

I have to figure out what the expected shedding of a brush might be (for a maintenance document).

It's a commercially available rotary scrubber 2" diameter, with 0.016" nylon fill (no specs except diameter), fused tufts in a polypropylene disc, each tuft about 0.875" long. So, pretty stiff.

They'll be rubbing on the surface of a 40-mesh stainless steel screen, and the material being screened is not abrasive.

In the action of scrubbing on that screen, each bristle will deflect no more than about 10 degrees from its attachment, and the brush will oscillate slowly, so they will deflect both ways about 10 degrees. (at the tip, bending uniformly over their length, I expect).

There's only enough pressure on the brush to ensure that it keeps the holes in the screen clear of gummy stuff which blinds it rapidly -- maybe as much as 8 ounces of down-pressure (but I think that's meaningless unless you know how many bristles, how densely tufted, etc... and I don't know those things).

We sized the screen openings so the bristles cannot fall through if they shed, to keep lost filaments out of the product stream. Wear particles are not a problem, even if they go through.

We have the option to "break them in" before installation, if that would be wise.

I told the customer I guessed the filaments would wear out in length before they began to shed; but I'd like to confirm, and figure out some sort of estimation on their life or wear rate.

Thanks, Tom. Lloyd

Maybe I'm not aware of how mesh sizes are measured, but 1/40 = 0.025", so a 0.016" nylon bristle would seem to go through it.

Yeah, try to get all the critical info to Mr. Brush Engineer.

Got nylon magnets? (Sorry, couldn't resist.)

That's the same SWAG I'd make. Tawm'll probably know, or at least be able to direct you to the info, though. Um, unless they're Chiwanese brushes. In that case, he's likely to "Gibbs" you upside the haid.

Larry Jaques fired this volley in news: snipped-for-privacy@4ax.com:

Mesh size most usually refers to "wires per inch". Wires often have more than zero diameter. (in case you didn't know that already)

Since we work with chemical compounding automation, milling machinery, and automatic screening machinery -- Y'think we might know something about the size of the wires used to weave the screen?

Look up woven wire cloth -- fun ride if you go through ALL the details.

I wasn't asking him if the filaments would go through the screens. We already worked all that out, thanks.

I was asking him what his experience was with shedding, so I could put something more than a friggin' GUESS in a maintenance manual.

Lloyd

I hear ya Lloyd, but I've seen you not answer the question asked once or twice two. LOL.

Frustratin' idden' it?

LOL.

Knew the latter. Thought it was openings-per-inch. Now I know. Thanks.

One would soitenly hope, oui?

I may do that...in between watching the several Harry Potter movies I brought home from the library today. I have an actual weekend to myself for once!

Grok that, but you need the nylon magnet for the _top_ side of the screen.

That's always nice. We all just loooove manuals written by clueless managers and such, don't we? Kudos on trying to do the best you can. So few do nowadays.

I just received a replacement stainless steel transplant shovel from Lee Valley Tools in Canuckistan last week. They heard "broken" and sent the new one, asking that I return the dead one in the same box using their supplied postage-paid label. Those guys know customer service!

You're right, the brushes will wear much more than shed. Nylon is the best fill for the application. They will last a long time! But, there is no way to predict the amount of wear or shedding without experimentation. Whatever you document will be consistent. I don't think breaking them in will make any difference, just remove any loose fill .

I still want that brass magnet you promised me!

Larry Jaques fired this volley in news: snipped-for-privacy@4ax.com:

Heh! Think about it, Larry! You'll go home, have supper, think about it some more... THEN LAUGH!

Wires-per-inch and openings-per-inch say exactly the same thing. What is never said when MESH is specified is how big the holes are. For that, you need to go to the specs on a particular screen... see the wire size. Usually, they calculate the opening size for you, too, but if not, its just simple arithmetic; invert the mesh and subtract the wire size from that.

There are several 'standards' concerning how thick the wires should be (bolting, milling, etc.), but it boils down to getting the specs, to make sure.

Then there is "space cloth", where not the wires or openings per inch are specified, but the actual sizes of the holes.

Fortunately or unfortunately - depending on how you look at it - we build machines from the ground up to do things with explosive substances nobody has ever built one for, before. So sometimes we bump up against limits in the industry's general experience with how certain tools or machines behave in these applications. We do a lot of scouring of other industries' experience, too, but still often come up goose-egg.

Lloyd

Lloyd

"Bob La Londe" fired this volley in news:l66opn$c3b$1 @dont-email.me:

No... I was just trying to educate Larry on what we'd already done, and already know. If I took exception to anything, it was just that we might not be thoughtful enough to consider the potential for loose bristles getting into the product stream. Stuff like that is what we get paid for.

Tom hasn't answered yet; neither 'to' nor 'not to' the point.

LLoyd

You're exactly right. The finer the wire, the larger the openings.

That's a problem when some rebel comes out with a "heavy duty" version. Then there's the metric v. Imperial measurement variance.

I guess your own standard has to be set and told in the product manual, doesn't it?

_That_ is the only one which truly makes sense.

You are so lucky you never grew up. Most of us boys have to grow up and away from our explosive childhoods. I remember once when my mother came running into my room, asking if I was OK. I had been seated in front of my chemistry set playing with calcium carbide in a Clorox bottle, and when I came to the end of squeezing it, the flame decided to go back inside the bottle. The resultant explosion was a bit smoky and loud, and it blew me onto my back. I was lying on the floor in a smoky room laughing (out loud) at my stupidity when Mom came in. Needless to say, I had a healthy new respect for carbide and I got to thing about it for a month while my chem set was off limits.

Do you have to buy various products to see if they meet your specs in the machines, too, or is precision of screening less important? I would think it to be fairly important for the consistency of your compound(s).

One question came to mind when you described the machine. How do you let in new material to screen? Is the brush lifted periodically so more can flow under it, or does it just rush in from the side, or are the clusters of bristles wide enough to allow material in between them, or what?