Grease for Gearbox

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?

Hi Mark,

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

What were you using your monsters for and did it all meet a happy ending? I had a commercial moulding shop.Presses up to 600 ton compression/ 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.

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

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.

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')

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.

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

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

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?

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