Grease for Gearbox
bromide
for processing rubber compound.
It has two sets of gearing, one for each roll, and the lower gear set in the
train runs in a bath of "treacle" and carries up a glob of grease to
lubricate the engaged teeth in the train.
Underneath the two rolls is an additional gear train that allows the user to
set a 1:1 ratio or a 1:1.16 ratio that applies a shearing action between the
two rolls. This gear train runs in a thicker grease (similar consistency to
lithium gp grease)
I have removed as much of these "lubricants" as I can, because they are
contaminated with various rubber fillers etc.but am not now sure what I
should buy to put back in !!
The mill is a Bridge 6"x12" machine built in 1965 - does anyone have any
suggestions what I should use?
Happy Christmas all
Dave
ma...@ems-fife.co.uk
I used to have one of these.A little Bridge lab mill.I also had 60"
mills with 150hp motors on them.We would have used a 140 grade ep oil
on the enclosed gears and blackjack on the open ones.Blackjack is a
high pressure grease with tackifier to keep it on there.
Is Farrell Bridge not still on the go to ask?
What are you using it for?
bromide
Thank you for replying, I hadn't expected to find anyone who knew what it
was - let alone owned one !!
We are going to be using our lab mill for compounding small (up to 5Kg)
batches of silicone rubber with metallic powders to make the compound
electrically conductive; this material is then used in the fabrication of
electrically conductive gaskets for radio frequency interference control (or
EMC as it is also referred to)
Would you totally fill the basin under the open gears with "black jack" or
just coat the gears - I am a little concerned about contamination during the
mixing process and had thought to be more conservative in the application
and clean/re-apply on a scheduled basis instead?
I haven't yet checked if Farrell Bridge are still going, I believe they were
based in Castleford?
What were you using your monsters for and did it all meet a happy ending?
Something British Industry doesn't enjoy too often :-(
Great to hear from you
Best regards
Dave
<ma...@ems-fife.co.uk> wrote in message
news:da2f5ffd-9671-4063...@m25g2000yqc.googlegroups.com...
ma...@ems-fife.co.uk
ending?
transfer.Ran 24/7,50 weeks a year.
Life wasn`t my own and to be honest the business would probably have
been in trouble now due to cheap imports,although we did export
certain products worldwide.
Big mills were used for blending/sheeting compound.I used to do a fair
bit of white silicone on a lab mill and for that machine used a clear
non staining food industry grease.
Mark.
Peter Neill
The last time I used a 2 roll mill was about 30 years ago, but one
thing I do remember was that the rollers were steam heated. However I
suspect you could get away with water heating, but it is another thing
to consider.
I used to use them in the University Lab in the NCRT/LSPT for making
experimental rubber compounds back in the early 80's,so my memories
are a bit sketchy.
Peter
ma...@ems-fife.co.uk
> The last time I used a 2 roll mill was about 30 years ago, but one
> thing I do remember was that the rollers were steam heated. However I
> suspect you could get away with water heating, but it is another thing
> to consider.
>
The last thing you need on a rubber mill is heating.The friction
creates that and you need chilled water to cool them.Otherwise you
have to wait ages between batches for the rolls to cool down or your
compound starts to cure in the mill.
Mark.
Charles Lamont
> The last thing you need on a rubber mill is heating. The friction
> creates that and you need chilled water to cool them. Otherwise you
> have to wait ages between batches for the rolls to cool down or your
> compound starts to cure in the mill.
I seem to remember the big and dangerous* buggers being called 'Banbury'
mills. Is that right?
(* 'Not To Be Used By Operators Who Can Reach Beyond This Mark')
--
Charles Lamont
ma...@ems-fife.co.uk
>
> I seem to remember the big and dangerous* buggers being called 'Banbury'
> mills. Is that right?
>
> (* 'Not To Be Used By Operators Who Can Reach Beyond This Mark')
>
> --
> Charles Lamont
The "Bambury" was an internal mixer IIRC.The open mills did have the
sign on them for operators.The plan was that before they could reach
the "nip" they had tripped the drive and the brake stopped the rolls
within 2" of travel on the circumference.
Didn`t stop them climbing up on the frame to reach further in.
Peter Neill
I know for a fact that is wrong Mark, on several counts, although I
will admit that the mill rollers also had cooling, but that was to
maintain a level of temperature
The curing (cross-linking actually) only occurs with the presence of
heat AND a vulcanising agent. The purpose of a two-roll mill is to
soften and masticate the raw rubber so that additives can be
introduced to it - whilst in the two-roll mill. Sulphur is a slow
vulcanising agent and no way will it cure a bit of rubber in a two
roll mill without an accelerator added and a very lengthy mixing time,
and even then it wouldnlt cure properly.
The NCRT/LSPT lab I was referring to was the National College of
Rubber Technology (London School of Polymer Technology) at the London
Metropolitan University where I studied for my Licentiateship in
Polymer Technology. I still have my notes and practical write-ups
somewhere up in the attic, but it's a bit cold to go up and search for
them <G>
On a latter post, I agree that the Banburys were indeed internal
mixers, and much safer than a two roll mill. On the two-roll mill (as
I'm sure Mark will agree) you fairly constantly cut-and-fold the mix
as it approcahes the 'nip' in order to get an homogenous distribution
of the raw rubber and ingredients.
Incidentally, the term 'bulk fillers' in rubber also includes floor
sweepings, wood shavings/sawdust, and the contents of the rubbish bin!
I was a little bit amazed when we were taught that :)
Peter
ma...@ems-fife.co.uk
>
> I know for a fact that is wrong Mark, on several counts, although I
> will admit that the mill rollers also had cooling, but that was to
> maintain a level of temperature
> The curing (cross-linking actually) only occurs with the presence of
> heat AND a vulcanising agent. The purpose of a two-roll mill is to
> soften and masticate the raw rubber so that additives can be
> introduced to it - whilst in the two-roll mill. Sulphur is a slow
> vulcanising agent and no way will it cure a bit of rubber in a two
> roll mill without an accelerator added and a very lengthy mixing time,
> and even then it wouldnlt cure properly.
> Peter
Peter
you seem to have forgot a lot of what you were taught.
I owned and run a small company moulding over 100 tonnes of rubber
every month.
I have never mentioned sulphur anywhere and agree that it would be a
long cure time if sulphur was the only vulcanising agent in the
compound.
We were modifying commercial compounds,that is,compounds which were
manufactured to my formulas and which had all the accelerators etc
already in them and adding various things to them to give enhanced
properties.We did this because we did not want the commercial
compounders and our competitors to know what was in the compounds we
were using for some of the very technical mouldings we were doing
Most of the modifications were done on small mills up to 24".
On the big mills we were sheeting compounds which I sourced worldwide
in a non sheet form.These compounds also were fully compounded.
Although I had steam for heating the moulding presses I never had
steam on any of the mills.But,I did have a large cooling tower and
pumped,chilled water to all the mills.
Your explanation of the use of a two roll mill is is fine,if you are a
student or in r&d.In a commercial enviroment you do not use two roll
mills for compounding,you use them for sheeting out the compound the
the internal mixer dumps out.
Consider the average Bambury or Intermix can compound a 250kgs batch
in about three minutes or less,do you think it`s cost effective to use
a two roll mill.Even an 84" mill can`t look at these sort of
quantities in that time frame.
As a favour I used to repair large earthmover tyres for a mate.Take
some frictioned cord,some sbr add a bit Zix to the compound and it
would cure with a light bulb.
BTW,have you heard of RAPRA?
Peter Neill
Quite agree - commercial compounding and R&D probably require two
quite different approaches, and I think that may be at the heart of
where our opinions differ. On that basis I think we are both correct.
I know RAPRA quite well. I provided consulting services to them on
insert moulding techniques, approachs, and pitfalls a few years back
when I was technical director of T.S.E.
Peter