SPRAYABLE OPEN-GEAR LUBRICANTS

Dear Barun,
I think its a general staement of comparision that the performance levels of higher base oil viscosity is better than that of a same compisition of lower base oil viscosity.
But of course the perfomance levels are not exhustively listed in any datasheets and neither they are conducted here.
Simulation are not as accurate as field results and also exhaustive field results are missing.
I think in the 2nD PARA we are only talking about adequacy of 500cst Vs 1000cst.
Its not of better performance.
I have some test results done for comparision between lubes of diffeent viscosities and brands done by BHP Australia in their lab as well as a write up on spary Lubricants from Svedala and can share with you if you like.
regards
Arupanjan

I have been wondering a bit on this topic myself as the plant I work in has large roll dryers with the trunion rollers and the spur gears spray lubricated with ISO VG 46 AW hydraulic fluid. Would anyone consider this an adequate lubricant for such a heavy load application. At least there isnt alot of thick lube to clean up around the base.

Is the spray continious? and of course AW 46 Oils I have my reservation, but the best persons are OEMs of the machine to permit the minium ISO VG range of the oils for this oil.
Well u might be saving on clean up and disposition but some one has to check the temp of the gear tooth flank amd vibration of the drive system before commenting.

Interesting topic....and without a doubt controversial.
The debate between the residual compounds and the greases and the synthetics and the PIB fortified open gear lubes has been ongoing for a long time.
As was pointed out some of the proponents will claim that their product is the best for your application, bar none. If you ask them for the engineering calculations and the standards by which they base their statements most will be unable to provide much meaningful data. What they offer up is a list of people who are using their product, testimonials from other users that may or may not know the difference in lubrication performance. A customer that might have gotten a 2X increase in the MTBF of their pinions but it is still 1/2 of industry average life. Long on hyperbole but low in fact.
In my maintenance life I have seen the tried and true asphaltic residuals used with success. I have seen some grease used with success and even a heavily fortified PIB mineral oil perform well. But I have never seen 1 product family that was suitable (the best) for all applications.
There is a school of thought that suggests that if the lubricant is too thick then it has the effect of causing the generation of localized pressure ridges that cause the effect of plastic flow. The rational is that the load is focused on a localized point instead of being spread out across the gear face.
I would suggest that serious consideration be given to assessing and understanding the particular requirements of the application and then performing the calculations necessary to at least provide a starting point from which to specify the requirements.
So to the question "can we generalize by saying that {in open gear grease} that a higher viscosity is better? My opinion is yes because most North American greases use base oil viscosity's that do not match up with fundamental viscosity requirements for the applications that I have performed the calculations for. You will find that most of these greases carry a fairly high amount of solid additives, obviously to fill in the void that the base oil cannot.
Will consensus ever be reached on this subject? I doubt it, as long as there are no definitive testing protocols that can simulate and hence guarantee performance standards.

Re the issue of the AW ISO 46 oil. If the rim speed is sufficiently high enough then an ISO 46 might work. What kind of life are you getting from the spur gearing and are the failures related to scuffing or pitting across the face and hence lube viscosity or for other reasons. Understanding your failures will help you to determine the suitability of the lube. A 46 seems low but...........

re: the sprayability of different greases, sprayability is a function of the synergies between the base oil and the thickener system as well as the recipe followed when making the grease. Generally the higher the combination of NLGI grade and base oil the higher the volume (ratio between lube and air) and velosity of air that is required. I have had success with a Spraying Systems vendor in the past to run some tests for us with different lubes (minimal or no charge). You tell than the capabilities of your system and provide a sample of the old and new lube and they run the comparisons and recommend the nozzles etc suitable for the new lube.

hope this helps

regards........

First of all I must agree with Allan and thank him for some insight as well as his own views on that.
Secondly this is a very very serious topic of Debate in India, specially in the cement industry.
Third I would comment the following and also require inputs from the forum to learn and perfect the subject and share with every one what I learn.
We now see in Indian Market the following products
residual compounds, the greases and the synthetics from some multi national company- some are black due to high concentration of solids, max 10%, and some are over coming the prblem of low viscosit and high solids with high base oil viscosity to get the same property and performance, which are transparent and making the gear surface inspection meaningful, which is of absolute necessasity. Its also a fact that there might have a 2X increase in the MTBF of their pinions but it is still 1/2 of industry average life. Long on hyperbole but low in fact.
I think AGMA gives a guide line based on the PCD of the gear and Face width of the pinion and whether, the spray is on the gear or pinion the minimum amount of Lube necessary for a particular type of Lube that is the viscosity of the grease either in Cst or SUS and so also the OEM specifies according to the peripheral speed and gear material. And that’s how the calculations are based. If there is any thing else I would like to know that form the forum. The asphaltics have success but are banned now due to Environmental as well as health reasons as well the revision of Design parameters in gear materials.
As far a thickness of the Lubricants, if we are mentioning NLGI grade – Higher base oil viscosities are generally with low consistency i.e. 00-000, and if the spray is uniform then there is no chance of localized pressure as the knowledge goes and hence plastic deformation should not be the issue.
Considering the gear is new and peripheral speeds are high low viscosity greases may be used as hydrodynamic conditions are achieve able in high speeds like in mills of certain speeds about 20- 25 rpm. And I also Agree with Allan a higher viscosity is better for protection.
As in north America, so also in Europe, the base oil viscosity is supported by higher solids, but the potential danger remains on the purity as well as type of solids. The higher the base oil viscosity lower is the percentage of solids – is that right Allen?
As far as simulation and test methods are concerned, there could be 2 the modified FZG Test of A/2.76/50 and not A/8.3/90 for reasons of channeling in higher viscosity sump lubrication giving misleading results. There are some suppliers in India proposing A/8.3/90 as the test and THE CREDIBILITY of this test in open gear systems is questioned by FZG also as per information because of the test results and field experiences are contradictory.
A SRV test was hence done by ball on plate, in Australia to get the pitch line stress effect as well the co-efficient of friction vs. time and wear and results were plotted gave a better insight on performance capabilities and was in commensurations with the field result.
Yes Again ISO- 46 speed is an issue but the but remains
and so also the comment on sparybiliy is fully agreed with the opinion of Allen.
Any further input please on this issue.
regards

I think looking at takifier levels and anti corrosives could be just as important. As well as how long its hanging in there throughout the service life.

Yes they are important and regarding how long......
US Steel retention test is important.
regards
Arupanjan

Dear Arupanjan,
Dr. Barun has started an interesting debate.
Unfortunately there are no international specifications for Open gear lubricants. Each company tries to propagate their products indicating their benefits/advantages and the customer has to make a choice based on experience, cost, data claimed by lubricant supplier, OEM approval and its performance in other plants.
This could be because of different operating conditions.
You may be aware that in India we are trying to develop the specifications for Open Girth Gear Lubricants.We have studied analysed no. of lubricants and they vary a lot.Yet each one claims to be the best.
The subject of higher base oil viscosity better or not is really a babatable issue.What Ifeel is that depending upon the requirement(?), the base oil viscosity should be chosen.

Dear Mr Vijay
Any specific reason why the mail was addresses to me only?
Having asked that I would like to put forward my observations and comments:
Open gear Lubes are sold in a similar way as any other lubes or products.They are specified in similar parametrs like any other grease or oils by international standards like ASTM or DIN.
But unfortunately in Indian Industry, there are very little conclusive data on the performance of each product, either from users or independent bodies, though we have seen these lubs in the country for almost last 20 yrs or more,
I will be obeliged if you could share the process of developing the specifications for Open Girth Gear Lubricants. and also the procedures & results on-"We have studied analysed no. of lubricants and they vary a lot.Yet each one claims to be the best".

How ever I have gone through some elaborate procedures and logics of testing of OGL by SVEDALA-USA cuurently Nodberg and BHP Mineral systems of Australia.I have also seen good comments made by Alan, who seems to have worked with open ideas, in his elaborate note on this subject.
I think Svedala, BHPs are not less knowledgebale on this subject and we need to trust them, if we have to make an advancement on this and look at the global experiences.
regards
Arupanjan

No special reason why it was addressed to you Mr. Arupanjan.But you have been very active in these discussions.
Yes I agree with you that there are no sufficient data of performance of the product against the operating conditions/mill specifications.
You are aware that there are products from KLUBER, Reiner, OKS, Croft, Shell, Castrol etc.each having different specifications.One of the product has Weld Load 400 Kgs.yet claiming to be highly efficient.
NLGI India Chapter has been working to arrive at uniform specifications for these products like ISI specn. for Gear Oils, Turbine oils etc.
But its always nice to get the views from others on these subjects.
Thanks.
Vijay

I know the product which is having 400 Kg of weld load and since that product is designed for a unidirectional rotation machine 400 kg is adequate. Other Products are designed to meet the requireemt of both unidirectional and reversible rotational products.
I think they dont sell this product of 400 kg in the reversible load application.They have a product of 800Kg for that application. Is that right?
Any way as I said and also reconfirm that these products are tested and evaluated by OEMs and only a basic engineering is required to evaluate the products.
Other info is Renires have been taken over by Fuchs and Kraftt has been taken over by Molykot
Regards

quote:

write up on spary Lubricants from Svedala

Dear Mr. Arupanjan Mukherji.

Could you send me the details of write up on spary Lubricants from Svedala on tradingdubai@gmail.com

Hello Mr. Mukherji,

Do you still have the test results done for comparision between lubes of diffeent viscosities and brands done by BHP Australia ?

Pls. kindly email : dhimit@creative-innovation.com

Open Gear Lubricants - My favourite topic.
Where to begin, firstly let me say i have personally been involved in converting approximately 120 open gear systems from one type of open gear lubricant to another. I have seen systems operating on old technology asphaltic, new technology asphaltic, low visicosity base oil fluid greases, synthetic compounds, high viscosity base oil greases and the new generation heavy viscosity synthetic oils, and my personal favourite was a set of 5 mills running on ISO220 gear oil.

There are a number of issues to take into account when looking at open gear lubrication and the lubricant is only one of them, the application method, lube quantity, spray nozzle design, spray nozzle position, pump and distributor configuration, outside contamination, shroud sealing design, slumpability of the spent lubricant, sprayability of the lubricant, low temperature pumpability. Maintenance practices at the site are one of the most critical parts of the open gear lubricant puzzle. I have had mines using the best lubricant in the world and having great results only to turn up to site and find a knife stuck in the lube system alarm reset button because of the annoying noise it was making. When I opened up the pinion cover there was sparks coming off the pinion as the lube drum had run out about two days earlier.

There are lot of comments which can be made about the various lubricant tests available, the BHP modified SRV was one in which I participated and we actually came out at or near the top with our product but they still would not use it as they deemed it cost too much. (It cost a lot less than the SRV test cost to run let me tell you.)I also have had products tested with the South Africa University. At the end of the day most reputable open gear lubricants will usually work to some degree if they are applied correctly and are part of an ongoing monitoring and maintenance program. Different lubricants will perform better in some applications, this is usaully due to the application system or associated conditions.

There is one large company in Australia who continue to spend thousands of dollars per year removing shrouds to dig out the spent Open gear lube when they know that there are products available that will flow beautifully out of the shroud and stop clogging up spray nozzles. There are companies who will continue to let liner bolts leak and pump slurry into the open gearing and tear the pinion to bits but wont stop the mill because of production. I have seen a 12mt diameter dual drive SAG mill that was wearing out pinions every 12 months until we pointed out that the spray nozzles were aimed at the unloaded face of the girth gear. Oh and that mine with the ISO220 gear oil, they were wearing out pinions every 18months with no visible sign of failure and the pinions were running at ambient temperature. The pinions would just get thinner and thinner until they broke a tooth. The gear oil provided a lube film but it was not suffient to hold apart the metal surfaces and even though there was no scoring or pitting it just slowly removed the metal.

Sorry for the long winded comment, my advice after all this is look at the technical support you get with the lubricant. That is the single most important issue with open gear lubrication, if you do not have the technical backup and regular site visits to monitor the mill and your maintenance teams. Some companies believe that they have the technical expertise inhouse to manage the open gear lubrication, but nothing compares to having another set of eyes looking at your equipment and comparing it to the industry.

I note that a lot of these comments come out of India, I have spent time conducting open gear surveys in the mining industry in India and my advise would be the same as above but with more emphasis, focus on the technical support being provided, this is worth more than the cost of the lubricants.

Hope the helps,

Rodney Fitzpatrick.

I have read with interest various issues discussed on Girth gear lubricants. Most of the views are from academics and practicing engineers. I am from a lubricating oil manufacturing company and would like to learn and contribute to some of these discussions.

Currently girth gear lubricants is done using three types of lubricants
1 Mineral Oil lubricants
2 Bituminious lubricants with tackiness additives
3 Sprayable Greases

The environmental concerns are forcing many cement mills and power plant engineers to use sprayable greases. While we have a range of products meeting all three requirements, we are looking for practicing engineers who could help us monitor the performance of the sprayable greases. Are there such persons around? What services do they provide? What services are required? How can a bridge be formed between an oil manufacturer and the user through a service provider so that the user is benefited while providing the manufacturer valuable inputs for testing the efficacy of the product.

http://www.memolub.be/application.php?PHPSESSID=ea50d73...b45fd3152cc0faa9d662

On this site shows how to lubricate open gears, chain, conveyors, rollers etc.