Tagged: strategic reliability solutions

Is Oil Analysis the Only Method of Varnish Detection?

Varnish will deposit in layers and adhere to the metal surfaces inside the equipment. As it continues to deposit, the layers will eventually accumulate until it reaches a point whereby it can cause significant changes to the clearances of the components.

There have been instances where shafts in rotating pieces of equipment have been moved due to the build-up varnish. This is where vibration analysis can be instrumental.

When the vibration analysis method is used, it can detect any small changes in the alignment of the shaft in rotating equipment. As varnish continues to build on the inside of the component, vibration analysts can detect if the shaft observes some misalignment over a period.

This may be easy to miss as sometimes the varnish which has built up can be wiped away, causing the shaft to resume its proper alignment. Thus, these technologies should be used in tandem before conclusions are made about the presence of varnish.

Another detection method that can be employed is the monitoring of temperature fluctuations. As stated earlier, varnish can form an insulating layer trapping heat. There have been case studies that demonstrate that bearings experiencing varnish tend to display temperature increases.

Typically, these temperature patterns assume a saw-tooth pattern where temperatures rise continuously as the varnish builds up. The varnish becomes wiped away, and the temperature is reduced drastically.

This saw tooth pattern of temperature variation is characteristic of varnish formation. In some cases, the formation of localized deposits on bearing surfaces may cause temperature escalations without a corresponding MPC increase. In this case, the bulk oil may not show any degradation, yet temperature excursions may be experienced at the bearing surface.

Want to read the entire article? Find it here in Precision Lubrication Magazine!

Lubricant Degradation

Can Lube Oil Varnish be Detected?

Detecting something is the first step towards formulating a solution to minimize its effects or eliminate it from a system. In the case of varnish for lubricated assets, a few technologies are currently being used to detect its presence.

As seen at the beginning of this article, varnish can exist with various characteristics depending on the degradation mechanism which aided in its formation. For this article, the degradation mechanism of oxidation will form the main focus as it is the most prevalent pathway to lube oil varnish formation.

During oxidation, the first chemical change which can be observed in the lubricant is the depletion of the antioxidant additives. This is where the knowledge of phenols and amines is critical.

As per Livingstone et al. (2015), these antioxidants can form synergistic mixtures in mixed antioxidant systems. When the free radicals react with the phenols, they become depleted but can regenerate amines. Thereby, the phenols are sacrificial.

Thus, when performing the RULER analysis, one can find that the concentration of the phenols will typically deplete quicker than the amines. This provides the analyst with a good overview of the amount of oxidation that has taken place in the lubricant.

The RULER analysis is one of the oil analysis methods which can provide early detection of the occurrence of oxidation.

It has been shown that the physical changes, such as polymerization, will only begin after this chemical change of the depletion of antioxidants. It is at this point that the actual deposits will begin formation.

Unfortunately, oil analysis tests such as viscosity and acid number only show significant changes after the deposits have been formed. At this time, it may be too late to implement technologies to mitigate varnish formation.

The Membrane Patch Calorimetry (MPC) oil analysis test (ASTM D7843) can offer analysts insight into the estimated amount of insoluble varnish currently within the system. These results have three main ranges which identify the severity of the varnish, namely, 0-20 (Normal), 20-30 (Abnormal), and >30 (Critical). Oil analysis tests can effectively provide the operators with some awareness of the current condition of the lubricant and its tendency to form varnish.

Want to read the entire article? Find it here in the Precision Lubrication Magazine.

Lubricant Degradation

The Six Forms of Lubricant Degradation

Oxidation

The most common form of degradation is oxidation. While this is the most recurrent form of degradation, the term is often misused to describe all forms of degradation. During Oxidation, a free radical is formed, which is highly reactive. Its primary purpose is to create other free radicals which can attack the base oil.

However, lubricants have been formulated with antioxidants. These knights in shining armor react with the free radicals to neutralize them and protect the base oil. As such, during the oxidation process, one will notice a decline in the concentration of antioxidants typically evaluated using the RULER® (Remaining Useful Life Evaluation Routine) test.

Eventually, the antioxidants become depleted, and the free radicals begin attacking the base oil. During this stage, polymerization can occur, which leads to the formation of deposits within the lubricant. Not every deposit is chemically similar.

The deposit will gain its characteristics from its environment and the products present during the chemical reaction. When these deposits occur, they can get lodged in the smaller clearances (particularly servo valves), which leads to possible malfunctioning of the equipment. Due to the nature of lube oil varnish, it can act as an insulating layer that increases the temperature throughout the equipment.

Thermal Degradation

Another form of degradation is called thermal degradation. As its name suggests, heat is one of the environmental conditions required for this degradation mechanism. During thermal degradation, the oil can experience temperatures over 200°C.

The Arrhenius equation is one of the industry’s rules of thumb whereby for every 10°C rise over 60°C, the life of the oil is essentially halved. At 200°C, the oil is cooked and produces carbon-based deposits, which is this mechanism’s characteristic type of deposit. The FTIR (Fourier Transform Infrared) test is instrumental in identifying the presence of these deposits.

Microdieseling

One can argue that microdieseling is a form of thermal degradation and should be classed as such. However, during microdieseling, air becomes entrained in the oil and moves from a low-pressure zone to a high-pressure zone.

If the oil does not have good air release properties, then the entrained air will not make its way to be dissipated at the surface. This entrained bubble in the oil can cause temperatures to rise to 1,000°C.

The bubble interface usually experiences some carbon accumulation and then implodes. This can be through a high implosion pressure which results in soot, tars, or sludge, or through a low implosion pressure which can form carbon insolubles such as coke, tars, or resins.

Electrostatic Spark Discharge

Electrostatic spark discharge may be classified under thermal degradation as it involves temperatures over 10,000°C. During this mechanism, oil builds up static electricity at a molecular level when the dry oil passes through tight clearances in the equipment.

Eventually, the static will build to a point where it produces a spark, and free radicals are formed. This can lead to uncontrolled polymerization producing varnish, sludge, or other insoluble materials. One of the tell-tale signs of this mechanism is the presence of burnt patches of membranes on the filters.

Additive Depletion

Additive depletion is often a form of degradation which gets left behind. As stated earlier, additives are sacrificial and will be depleted over time. Their purpose is to protect the lubricant and the machine, but they can be significantly depleted in some instances, leaving them vulnerable.

This type of degradation can produce two types of deposits, organic or inorganic. During degradation, rust and oxidation additives can become reacted with other components. These types of reacted additives can form organic deposits.

Alternatively, inorganic deposits such as ZDDP (Zinc dithiophosphate) can deplete and form a tenacious layer. The Depletion of ZDDP will impact the wear rate as this is the antiwear additive.

Contamination

Often, the most unrecognized form of degradation is contamination. Some may argue that this is not a form of degradation. On the contrary, this degradation mode can be the initiator for other mechanisms such as oxidation, thermal degradation, or even microdieseling.

Essentially, contamination occurs when foreign material is present in the lubricant. Often, this foreign material can become a catalyst for one of the other forms of degradation. Therefore, it must be acknowledged separately, as only the degradation mode can be eliminated by removing the contaminant.

Want to read the entire article? Find it here on Precision Lubrication Magazine!

Lubricant Degradation

What is varnish or oil degradation?

Varnish is a type of deposit that forms on the surface of equipment in lubrication systems. It is caused by the oxidation of the base oil and the buildup of additives in the oil over time, forming a sticky, varnish-like substance. Lube oil varnish can cause problems in equipment operation by clogging filters, reducing oil flow, and leading to valve sticking and pump failures.

Lube oil varnish is no stranger to the manufacturing industry. It constitutes the substance of most operators’ worst nightmares and plant managers’ ultimate fears. For those who have been in the industry for the last decade, varnish is the sticky subject that unites all facility departments.

It can cause an entire manufacturing plant to shut down while sending the finance department into a frenzy trying to balance production loss with incoming repair costs. In the fight against lube oil varnish, all teams need to work together to ensure that it can be managed and possibly eliminated from the system.

What Is Oil Degradation?

Before diving into the world of varnish, one must first understand how it forms and the circumstances which have led to its existence. Within the industry, the term varnish is used loosely to define any form of lubricant-derived deposit found in industrial.

However, oil can degrade by several mechanisms, which require various conditions for degradation—as such, using the term varnish to describe any deposit formed within a machine does not suggest its mechanism of formation.

The lubricant begins its degradation journey from the moment the lubricant enters the machine.

A lubricant is composed of base oil and additives, of which infinite combinations exist. Additives are carefully engineered to protect the base oil and the equipment. As such, they can become depleted over time, leading to the degradation of the lubricant.

This becomes concerning when the additive levels have depleted to a threshold where they can no longer protect the base oil or the machine. At this stage, degradation is the most serious concern because its rate is greatly accelerated.

According to Mathura (2020), there are six major forms of degradation under which a lubricant can undergo. While some may argue that these can be grouped, some characteristics set these mechanisms apart.

Each mechanism has unique environmental factors which contribute to producing different types of deposits. It is critical to note that identification of the type of mechanism can assist operators in performing remedial works on their equipment to aid in preventing the formation of varnish.

Want to read the full article? Check it out here in the Precision Lubrication Magazine.

Certifications

Obtaining my MLT I & II certifications

The MLT (Machinery Lubrication Technician) exams are developed by ICML (International Council for Machinery Lubrication) and is seen as the entry level certification for those who are working in the field of lubrication. When I entered the reliability field (years ago!), it was one of the credentials I was told that I should obtain to allow others to take me seriously since I was a young female entering a male dominated world. Back then, the training for these exams usually took place as a week-long intensive course in the US followed by the exam. For me, this would have meant travelling to the US, studying for the exam, catching up on work, balancing some jet lag and then writing the exam. This approach didn’t work for me.

I may have taken the unconventional route and written my first book, “Lubrication Degradation Mechanisms – A Complete Guide” published by CRC Press and obtained my MLE (Machinery Lubrication Engineer) certification before thinking of these exams. After achieving my MLE and becoming the first person (and still the only female) in the Caribbean, I went on to secure the Varnish badges from ICML. These are the VIM (Varnish and Deposit Identification Mechanisms) & VPR (Varnish and Deposit Prevention and Removal) badges from ICML. I was the first female in the world to achieve these and to date, still the only female with these badges. I pursued all of these courses via On demand sessions from the master himself, Michael Holloway of 5^th Order Industry.

Everything at the right time

At the end of 2020, Mike approached me to write a guide book for the MLT Level I & II exams. My first question to him was, “How can I write the book for these exams if I don’t have these certifications?”. He assured me that the MLE content covered the topics in MLT I & II and then a lot more. We decided to work on writing the book and get the certification before the book was published. Surely enough after we submitted the pages to the publishing house, I began my preparation for the exam using Mike’s On Demand videos and the book we had just developed for these exams! I was preparing myself to take the MLT I first and then the MLT II right afterwards. Plus, Mike had a really good deal on the course content! How could I refuse?!

Unfortunately, life happened, or in this case death. In November, one of my parents contracted COVID and did not survive. While taking care of them, we also contracted COVID, the one with the long haul effects. Needless to say during the following months, I could not retain any information nor sit an exam. One of the side effects from COVID was brain fog and even after a couple of months this did not clear up to the point where I felt that I was ready to retain any information. I had forgotten basic info which would have been at the forefront of my memory and really struggled for some time to come to terms with everything that had happened and the new journey which lay before us. Our lives were changed forever.

Exam preparation

In May, I finally began to feel a bit better and restarted my MLT Journey with Mike’s videos and our certification book as our guide. This time, I had a physical copy of the book on my desk as it was already published (maybe things do work out in their own special timings). Getting back into study mode while running the business and dealing with never ending paperwork and legalities which surround a death was tricky. I was so grateful for the on demand courses to allow me to study on my own time, at my own pace, when I was truly ready. Also being able to book the exam and complete it virtually from my own space was terrific! The time and anxiety associated with taking an exam is enough, we don’t need to include traffic, getting to a physical location and the environmental conditions of the exam room into the mix!

If you’re preparing for the MLT exam, you have to complete Level I first. There is no skipping ahead to Level II as during the sign up process for MLT II, you have to include your MLT I ID#. My advice for scheduling the exams would be to schedule one on the Monday and the other by Friday of the same week.

Exam scheduling

Here are some tips on scheduling your exam:

When you sign up and pay for the exam you should allow 1-2 business days for processing.
Once you have been approved, then you can set your exam date. You will be notified via email with instructions on the next steps.
MLT I & II are both 3 hours, so choose your timeslot carefully.
Exam results take 2-3 days to process. You will receive an email with your results and grades in the various areas of the BoK.
Once you have passed MLT I and gotten your ID#, you should sign up for the MLT II exam immediately, if you intend to pursue it afterwards.
This will then take 1-2 days to process again. You will receive another email letting you know that you can choose your exam date.
Then, it’s on to schedule your exam date.
After the exam, you will have to wait for 2-3 business days to get your results.

Ideally, one should schedule a 2 week window for taking both the MLT I & II exams and receiving the results. You cannot take both exams in one day (just yet!).

Exam day

Once you enter the Examity portal, you will be asked to suggest a couple of security questions. Please choose these wisely and remember your answers as they will be asked on the day of the exam by the proctor. My advice would be to check the exam portal one day before your exam to familiarize yourself with the questions and answers as these are blocked out on the day of the exam. You should try to log on to the portal 30 minutes before the actual exam just to make sure you can get in and everything works. You will not be able to enter the “exam room” until 15 minutes before your appointed time. Afterwards, the Proctor will do their checks and balances with you where they ask to see your government issued identification (be sure your picture and expiry date are on the same side of this identification). They will also ask to see a 360 view of the room in which you are sitting to ensure it is clear.

During the exam, you can flag questions which you are not sure about and always go back to those afterwards. When you get to the last question, the button turns to submit but you don’t have to use this button until you are ready. Use your time to go back to your flagged questions, decipher the best suited answer and then press forward with your exam. Once you have finished and clicked the “Done” button, you should notify your proctor that you have finished the exam. They also have to close off the session on their side, so this is important to remember. You will see a page which comes up saying exam results, don’t panic! These are not your actual results, just a statement of the time you took. You will get your actual results within the next few days.

The MLT I & II Body of Knowledge

Here’s a look at the BoK for MLT I and MLT II. You will realize that the MLT II builds on the content covered in MLT I. Depending on where you are on your journey to machine lubrication, you can opt to take the both tests (one after the other of course) or simply start with the MLT I and then work up to the MLT II exam. In our certification guide, we used a Unique 5 Step process for learning:

Familiarize
Find Socrates
Be the Exam
Practice Exam
Explore

This unconventional method has proven to be exceptionally effective, not for only passing the exam, but to truly retaining the knowledge and becoming an expert in the content you’re studying. Certification requirements are discussed throughout the work, making this the ideal resource for prospective MLT I and/or MLT II certification candidates.

Here’s a quick overview of the content covered in the book:

Notes Outline: For the reader to complete. Aids in organizing ideas and thoughts.
Guided Cooperative Argument: A dialogue between authors concerning the topics. Helps answer questions that are asked on the job.
Statements of Truth and Exam Development: From the recommended Body of Knowledge, with space to develop your multiple-choice questions. Develops critical thinking process and understanding of how the exam questions are structured.
Body of Knowledge Outline: Works as a reference to help answer any questions that may arise.
Practice Exam: A mock exam designed to familiarize the reader with taking a multiple-choice test that is similar in structure and content to the real one.
Glossary & Appendices: List of common terms, charts, and tables with which all certification candidates need to be familiar.

I hope this helps anyone on their journey towards achieving their ICML MLT certifications. Good luck to those who are getting ready to take these exams.

Certifications / Lubricant Degradation / Reliability

Varnish Badges of Honour

Varnish is widely known as a primary culprit of equipment failure. This sticky enemy effectively finds its way into most of our equipment and causes operators, maintenance personnel and plant managers a series of nightmares. From unplanned shutdowns costing millions of dollars to sticking of servo valves on startup, or increases in bearing temperature, varnish usually announces its arrival. Once it has been found, there is typically a cause for panic but perhaps it just needs to be understood rather than feared?

The ICML VPR & VIM Badges

Recently (August, 2021), the International Council for Machinery Lubrication launched two new badges. These badges are, VIM (Varnish & Deposit Identification and Measurement) & VPR (Varnish & Deposit Prevention & Removal). These were created after the culmination of 3 years of work from the global varnish test development committee. It has been designed for those involved in all aspects of managing or advising lubricant programs especially those with the responsibility of recommending, selling or installing appropriate deposit control equipment or other mitigation strategies.

Most of the readers will already be familiar with my enthusiasm for understanding lubricant degradation. Thus, when these badges came out, I knew I had to secure them! While the requirements for taking the test suggest the possession of the MLT I or MLA I certification or 1 year of experience, I figured that my MLE certification would be an asset (as I haven’t gotten my MLT I certification yet, it’s on the list!). However, I wanted to make sure that I covered all of the elements in the BoK for both the VIM & VPR badges, so naturally I turned to the varnish guru himself, Greg Livingstone!

Fluid Learning – All the way!

1604954736_Fluid Learning Splash 2020-01

Greg is the CIO at Fluitec but he’s also the facilitator for the ICML VPR & VIM badges. What a treat! If you’ve never heard the name Greg Livingstone then you’re obviously not in the lubrication field. Greg has penned hundreds of papers on varnish and can be thought of as the varnish guru since he has extensive experience in this area. It’s a no brainer that I chose Fluid Learning to get me up to speed on what I needed to know for these exams!

Greg was an amazing facilitator and not only covered information relevant to the BoK for the exams but gave students a full overview about everything you needed to know about varnish. These on demand sessions kept me scribbling notes and nodding to myself and saying, “Oh that’s what really happens!” He presents the information clearly and adds some much needed humour into the sessions. It was an absolute privilege having him as my tutor for these badges.

VPR & VIM- What you need to know!

VPR - Varnish & Deposit Prevention and Removal

The VPR badge ensures that candidates understand proactive methods and technologies which can be employed to reduce the degree of degradation. It is also designed to confirm that they can sufficiently evaluate combinations of technologies to prevent and remove varnish including the proper steps to set up and implement an effective varnish removal system.

The topics covered in the VPR include:

Problems associated with Varnish & Deposits (20%)
Factors affecting Breakdown (28%)
Proactive Methods that can be used to minimize oil breakdown (16%)
Methods / Technologies that can be used to remove oil breakdown products and/or prevent deposits (36%)

The complete BoK for the VPR badge can be found here.

VIM (Varnish & Deposit Identification & Measurement)

The VIM badge on the other hand is more ideally suited for personnel responsible for recommending suitable oil analysis tests and mitigation efforts related to the deposit tendencies of various in-service fluids (application dependent). They would also be responsible for monitoring and adjusting these strategies accordingly.

The topics covered in VIM include:

Problems associated with Varnish and Deposits (20%)
Varnish and Deposit Composition (24%)
How Breakdown Products / Contaminants become Deposits (24%)
Oil Analysis Techniques that can be used to gauge Breakdown and Propensity towards Deposit Formation (32%)

The complete BoK for the VIM badge can be found here.

Exam tips!

The actual exams for both the VPR & VIM are set at 45 minutes with 25 multiple choice questions. Candidates must achieve 70% grade to attain the badges. Currently, the fee for the exam is USD75. Since there were overlaps of the content and the exam durations weren’t that long, I decided to sit both exams in one day. I will only advise this for those who are comfortable with doing this as exam anxiety and all that comes along with it can be stressful!

Here are a couple tips for taking these exams:

Log into the system 30 minutes prior to your scheduled exam time. This allows you to clear your mind, settle yourself and gives you an extra 15 minutes to figure out where the email is with your credentials! If you can’t remember your password to login to the system, this also gives you enough time to get that reset and sorted before the actual exam time.
The session only opens 15 minutes before the appointed time. During this time, you will converse with the moderator as they do the checks of the room and your National Identification. The moderators will engage with you and ensure that you are sitting the correct exam.
Ensure you have your National Identification on hand (your passport can be used as well). As long as it has your picture and the expiration date on the same side, it will be acceptable. For the Trinidadians, do not use your National ID card as we have our pictures on the front with the information on the back (I used my Driver’s permit).
Candidates have the option of “Flagging” questions to come back to them later. This is a great tool to help you to mark those questions you want to return to or double check.
There is a timer in the screen layout which helps you to keep track of your time. 45 minutes passes very quickly when you’re running through the questions!
Exam results for these badges come back very quickly as much as within a few hours or one day depending on the time of your exam.

Why do you need these badges?

As long as you work within the lubrication sector or interface with machines requiring lubrication, then you need to get these badges! Oil degradation occurs throughout the life of the lubricant whether it’s a small or large operation. By understanding how it degrades and ways to mitigate that degradation, you can save your equipment and avoid unwanted downtime. These badges were designed for the personnel in the field to allow them to make decisions regarding the lubricant and to empower them in taking steps to avoid degradation or mitigate it should the need arise. Consider it as getting your passport stamped by the ICML!

The courses offered by Fluid Learning are perfect for those seeking to understand lubrication deposits, what causes them and how they can be mitigated. While the content covered during these sessions align with the ICML VPR & VIM badges, they also add to a more holistic approach to varnish and deposits. Fluid Learning is an official ICML Training Partner and is currently the only one (of which I am aware) offering training prep for these badges. I highly recommend them for anyone seeking to learn more about or avoid sticky varnish situations.

At the moment of writing this article, there are only 8 people globally who have acquired these badges from ICML. I am the first female in the world to attain these badges but I will not be the only female for very long. Varnish is an issue which affects us all and we need to understand it, so we can prevent it and keep our equipment safe. I hope to see many more candidates with these badges in the near future!

Industrial / Strategic Tips

Food Grade Lubricants

Q: What are the classifications for Food grade lubricants?

If you’ve ever dealt with food grade lubricants in the past, you would have noticed that not all food grade lubricants are made to the same standard. When we think about it from a manufacturing standpoint, we can understand the need for varying specifications.

For instance, in a facility there are components that will come into contact directly with the food while there are others that will never make contact with the product being produced for consumption. As with all specifications, the prices of the lubricants created for regular non-food grade usage will differ from those that are specifically designed for food grade usage.

NSF Standards

NSF International is the body responsible for protecting and improving global human health. They also facilitate the development of public health standards and provide certifications that help protect food, water, consumer products and the environment.

Here are the different specifications for each of the food grades (used in most countries)¹:

NSF H1 – General or Incidental Contact

NSF H2 – General – no contact

NSF H3 – Soluble oils

NSF HX-1 – Ingredients for use in H1 lubricants (incidental contact) [usually additives]

NSF HX-2 – Ingredients for use in H2 lubricants (no contact) [usually additives]

NSF HX-3 – Ingredients for use in H3 lubricants (soluble contact) [usually additives]

Usually using a NSF certified lubricant goes hand in hand with an HACCP based food safety program (Hazard Analysis and Critical Control Points).

Here's a bit more info on the Categories and where they should be used³:

H1 - food grade lubricants used in food processing environments where there is a possibility of incidental contact.
H2 - non-food grade lubricants used on equipment and machine parts where there is no possibility of contact
H3 - food grade lubricants which are edible oils used to prevent rust on hooks trolleys and similar equipment.

ISO standards

There are ISO standards that govern food safety. These are;

ISO 22000 – developed to certify food safety systems of companies in the food chain that process or manufacture animal products, products with long shelf life and other food ingredients such as additives, vitamins and biocultures².

ISO 21469 – specifies the hygiene requirements for the formulation, manufacture and use of lubricants that may come into contact with products during manufacturing².

References:

Quick Reference Guide to Categories, NSF USDA. https://info.nsf.org/USDA/categories.html#H1
International Regulations for Food Grade Lubricants. Richard Beercheck. Lubes N Greases Europe- Middle East-Africa. June 2014. https://d2evkimvhatqav.cloudfront.net/documents/nfc_int_regulations_food_grade_lubricants.pdf?mtime=20200420102000&focal=none
Chemistry and the Technology of Lubricants Third Edition by Roy M. Mortier, Malcom F. Fox, Stefan T. Orszuilk (Editors), Chapter 8 Industrial Lubricants, C. Kajdas et al. Springer Dordrecht Heidelberg London New York. DOI 10.1023/b105569

Industrial / Strategic Tips

FZG Ratings

Q: What does FZG mean and why do gear oils have a rating?

FZG stands for “Forschungsstelle für Zahnräder und Getriebebau”, Technische Universität München (Gear Research Centre, Technical University, Munich), Boltzmannstraße 15, D-85748 Garching, Germany.

There are several FZG tests and these vary to establish different things. We will explore the two most common tests and what they mean.

The FZG tests were designed to accurately determine the types of gear failures that were influenced by scuffing, low speed wear, micropitting and pitting¹. While there are load other tests for gear oils (such as Timken OK test) these do not accurately identify the actual failure stages that gears experience.

FZG A/8.3/90

One of the most commonly used FZG test is the FZG A/8.3/90 according to DIN ISO 14635-1. This is mainly used for evaluating the scuffing properties of industrial gear oils². What do the numbers in the test mean?

The “A” represents an A-type gear with Pinion face width = 20mm, center distance = 91.5mm, number of teeth (pinion) = 16, number of teeth (gear) = 24. These are used in the test and are loaded stepwise in 12 load stages between Hertzian stress of pC= 150 to 1800N/mm².

The “8.3” represents the pitch line velocity of 8.3m/s in which the gears are operated for 15 minutes at each load stage.

The “90” indicates the starting temperature of the oil (90°C) in each load stage under conditions of dip lubrication without cooling.

After each load, the gear flanks are inspected for scuffing marks. However, the fail load stage is determined when the faces of all pinion teeth show a summed total width of damaged areas which is equal or exceeds one tooth width. In the gravimetric test, the gears are dismounted and weighed to determine their weight loss.

FZG A10/16.6R/90

The FZG A10/16.6R/90 on the other hand is used for automotive gear oils (GL4). It is the standard FZG gear rig test but the speed, load, load application and sense of rotation have been slightly altered.

The “A” represents an A-type gear however, these now have a reduced pinion face width to 10mm (from 20mm above).

The “16.6R” represents the increased speed of the pitch line velocity of 16.6m/s in which the gears are operated for 15 minutes at each load stage in a reversed sense of rotation.

The “90” indicates the starting temperature of the oil (90°C) in each load stage under conditions of dip lubrication without cooling.

FZG S-A10/16.6R/90

However, the FZG S-A10/16.6R/90 is the shock level test done for the GL5 oils. In this test the gears are directly loaded in the expected load stage and a PASS or FAIL is issued.

References:

ISO 14635-1:2000 Gears- FZG test procedures- Part 1: FZG test method A/8,3/90 for relative scuffing load carrying capacity of oils.
Test methods for Gear lubricants. Bernd-Robert Hoehn, Peter Oster, Thomas Tobie, Klaus Michaelis. ISSN 0350-350X GOMABN 47, 2,129-152 Stručni rad/Professional paper UDK 620.22.05 : 621.892.094 : 620.1.05

Industrial / Strategic Tips

Flender Specs

Q: Why should I use a Flender spec oil?

A lot of users ask about the need to use a Flender approved lubricant for their equipment! For a gear oil to be Flender approved¹ in one of its units, the oil must be of CLP* quality according to DIN 51517-3 and motor oils must meet and ACEA Classification E2, API CF/SF. Additionally, it must meet the minimum requirements as per their specified “Proofs of performance / minimum requirements table” where the lubricants are tested at approved laboratories.

*CLP (according to DIN 51517-3)² refers to an oil that contains additives which protect from corrosion, oxidation and wear in the mixed friction zone.

The manufacturer must also guarantee performance of the lubricant both for new oil and used oil up to a permissible range as per the following:

Mineral oils (API I & II and ester oils) shall be 10,000 operating hours (2 years max)
Mineral (API III) and Synthetic (PAO & PAG) oils shall operate for 20,000 operating hours (4 years max)
All oil must produce the minimum requirements with an average operating temperature of 80°C

The following are a list of tests required by Flender which must produce specified minimum results:

FZG Scuffing test in accordance with DIN ISO 14635-1 (A/8.3/90)
FE8 rolling bearing test in accordance with DIN 51819-3 (D-7, 5/80-80)
FVA micropitting test FV A 54 VII
Flender oil Foam test in accordance with ISO 12152
Compatibility with internal coating
Compatibility with outer coating
Filterability test FFT 7300 Rev.3
Compatibility with liquid sealing component

Flender specifies the viscosity in the series to be tested for the minimum requirements.¹

The Flender approval process ensures that the lubricant being used has been tested and can withstand some degree of micropitting, scuffing, foaming and is compatible with the surfaces in which it comes into contact. Thus, this makes the Flender approved lubricant more desirable for systems which place emphasis on the compatibility of all materials in the equipment (such as elastomers, paints etc). In conclusion, if you do have a Flender gearbox or equipment, it would be wise to use the Flender approved lubricant as they have gone the extra mile to ensure that the lubricant can protect your equipment.

Users can access a listing of approved Flender lubricants here: https://www.flender.com/en/lubricants

References:

Specification for the gear oil approval for FLENDER Gear units (AS 7300) link
Trends in Industrial Gear Oils by Jean Van Rensselar (STLE, Tribology & Lubrication Technology Magazine February, 2013) link

Industrial / Strategic Tips

Lubrication Regimes

Q: Is there only one type of Lubrication regime?

There are actually 4 types of lubrication regimes that equipment can experience and each component usually experiences at least 3 within their lifetime!

As per Noria 2017, the four different types of lubrication are; Boundary Lubrication, Mixed Lubrication, Hydrodynamic Lubrication and Elastohydrodynamic Lubrication.

Essentially, the best type of lubrication regime is Hydrodynamic as it provides the most ideal environment for both the lubricant and the surface. However, there are instances where other types of regimes can exist due to a lack of lubricant or contaminants.

Most components experience Boundary Lubrication on start up where there isn’t a proper layer of lubrication between the two surfaces. As such, the asperities of the two surfaces touch and can create wear. When we look at surfaces under a microscope, we can see tiny asperities (which we can liken to sharp or jagged edges) which are prevalent along the surface.

Even though a surface may appear shiny and smooth, when we microscopically examine them, the actual surface has a lot of asperities. Imagine, if two rough surfaces were sliding against each other, like a piece of sand paper against a wall, eventually parts of the wall will be removed due to the asperities of both the sand paper and the wall.

As more oil is gradually introduced to the component, it begins to experience Mixed Lubrication. In this state, the oil film is still not fully formed and is a bit thicker in some places than others. There are some contact areas where the surfaces will still experience boundary lubrication as well as elastohydrodynamic or hydrodynamic lubrication.

During this period, wear occurs due to the areas that are still experiencing boundary lubrication. However, it can be considered a transition phase as the surfaces move from tone type of regime into another as the lubricant film gradually increases.

When the component is full immersed in the lubricant, it usually achieves Hydrodynamic Lubrication which allows for a full film to be formed between the two surfaces and there is no longer any contact with the asperities. This is one of the most ideal forms of lubrication as it greatly reduces the wear between the two surfaces and the oil film safeguards that these can easily slide over each other thus, decreasing the friction between them. In this type of lubrication, the oil wedge is maintained in all operating conditions and guarantees that the asperities of both surfaces do not interact with each other.

On the other hand, with Elastohydrodynamic Lubrication, something quite special occurs with the lubricant causing the component to deform slightly ensuring that the film is maintained between the two surfaces. This happens at the highest contact pressure and ensures that the asperities do not touch whilst maintaining the oil wedge.

This type of lubrication usually occurs when there is a rolling motion between two moving surfaces and the contact zone has a low degree of conformity (Noria. 2017). Essentially, Elastohydrodynamic lubrication occurs when the lubricant allows the contact surface to become elastically deformed while maintaining a healthy lubricant film between the two contact surfaces.

References:

Noria Corporation. 2017. Lubrication Regimes Explained. https://www.machinerylubrication.com/Read/30741/lubrication-regimes