A Technical Data Sheet (TDS) gives you important information about a lubricant, including how it will perform in different conditions. This makes the TDS essential for selecting the right lubricant for your application. But what do all the fields on a TDS mean?
By Frans Pienaar, Technical Sales Manager
âA grease is a grease.â How often have you heard those words? Itâs a common phrase, used in many industries to indicate that any lubricant will do the job. But, like many common phrases, it simply isnât true.
Each lubricant is made up of various components, which are carefully selected to enhance performance in specific operating conditions. Choosing the right lubricant can significantly improve the performance of your machinery â and that selection process should start with the Technical Data Sheet (TDS).
Lubricants are made up of various components, which enhance performance in specific operating conditions.
What is a Technical Data Sheet (TDS) anyway?
A TDS is not a legal document. Itâs more like a marketing document for technical people. Lubricant manufacturers choose what information to include on the TDS â and the data listed will differ from company to company. Still, it should be possible to compare data from different products and companies, as long as you understand what the basic data fields mean.
In this blogpost, I explain the data fields in a standard characteristics table on an RS Clare TDS. In our characteristicâs tables, the key information is in the right-hand column; the middle column shows the test/assessment method (i.e. IP, ASTM, or OECD).
Understanding a lubricant TDS: Appearance and colour
A lubricant can be smooth, fluid, semi-fluid, etc. This is a very subjective characteristic and has no relation to the lubricantâs performance â itâs just there for information. The lubricant will also come in a specific colour â either natural or as the result of an added dye. Like the appearance, the colour has no impact on the performance of the lubricant.
Understanding a lubricant TDS: Thickener type
Thickeners enhance certain aspects of the lubricantâs performance â so itâs good to understand the difference between the most common types. There are many more thickeners than I have listed here, so check with your lubricant supplier to make sure you find a product with the ideal thickener for your needs.
- Lithium soap is a multi-purpose all-rounder. It has a high dropping point, good water resistance, good shear stability and good response to additives. (Thatâs why this has been the most popular thickener for more than half century!)
- Calcium soap provides very good corrosion resistance. Itâs also good for low temperature use (depending on the base oil).
- Sodium soap has long fibre structures which improve load carrying capability. But, as it dissolves in water, itâs not ideal in applications with water ingress.
- Aluminium soap has low shear stability, good water resistance and adhesive properties.
- Calcium sulfonate (in its complex form) has very good water resistance and shear stability with low oil separation. Greases with a calcium sulfonate thickener are known for their high load carrying capabilities.
Bonus fact: a grease is an oil with an added thickener. If a lubricant doesnât have a thickener added, then itâs an oil.
Understanding a lubricant TDS: Temperature
The temperature is probably the easiest field to understand. It tells you the extremes of temperature that the product will perform in and/or can be applied in.
Understanding a lubricant TDS: Work penetration
This tells you the consistency of the lubricant (i.e. how hard or soft it is). Itâs measured using the US National Lubricating Grease Institute (NLGI) classification system.
NLGI classification runs from a 000 â 6, with 000 being semi-fluid and 6 being hard (like a block of soap). A lubricant with a low NLGI number will pump easily, but it will also flow more easily, making it less than ideal in applications where the lubricant must stay in place.
Understanding a lubricant TDS: The drop point
Basically, the drop point is like the melting point â itâs when a semi-solid grease moves into the liquid phase. As a rule, the upper maximum operating temperature of a lubricant is usually 40-50 °C below the drop point. This is very important to know, as it tells you if the lubricant can be used at higher temperatures.
Understanding a lubricant TDS: Oil separation
Oil separation (also called oil bleed) is mainly an indication of the lubricantâs stability. Generally, some oil separation is good, as the lubricant has to bleed into the area where itâs needed. 5% separation is usually seen as the maximum separation permitted.
Load or pressure cause the separation to happen. (Itâs a bit like squeezing water out of a sponge.) So, if your application will expose the lubricant to very high pressure, choose a lubricant with a low percentage of oil separation.
Understanding a lubricant TDS: 4 Ball Wear Scar
This measure gives you an indication of how well the product protects against wear from abrasion over a long period. The shorter the scar length, the better the wear performance. 0.6 mm is good wear protection; 0.5 mm is excellent.
Understanding a lubricant TDS: 4 Ball Weld Load
The ball weld load shows you how a lubricant will perform under high loads (i.e. it tells you at what load the lubricant will fail). The ball weld load can be reported in Newton, but most people just give the number in kg. If you have a high-load application, choose a lubricant with a high ball weld test result.
Understanding a lubricant TDS: EMCOR corrosion
This tells you how well the lubricant will protect against corrosion under dynamic wet conditions. The test can be done using distilled water, synthetic seawater, or sodium chloride solution. The lower the number, the more corrosion resistant the lubricant.
Understanding a lubricant TDS: Copper corrosion
Some lubricants are corrosive to copper due to the presence of active sulphur compounds. This isnât relevant for many applications today, but if your lubricants will come into contact with copper components, you need to know how it will affect them. 1a indicates no copper corrosivity; 4c is high copper corrosivity.
Understanding a lubricant TDS: Water wash out
This shows how well a lubricant resists washout from a water stream. Itâs a consideration for outdoor applications: rain is a part of our everyday life, unfortunately! Any figure lower than 6% is good.
Understanding a lubricant TDS: Biodegradable
OECD 301B is one of the most common internationally accepted tests for lubricant biodegradability. PASS refers to a result of >60%, which is often referred to as âreadily or rapidly biodegradableâ. Itâs worth noting that this is a complex topic and there are various testing and reporting methods, depending on the industry and country.
Base oil characteristics
The base oil is one of the key factors in determining a lubricantâs characteristics. So, at RS Clare, we dedicate a special area of our TDSs to the base oil.
- The type tells you the type of base oil used, which gives you an idea of the performance and environmental credentials of the lubricant.
- Viscosity says how resistant the base oil is to flow at certain temperatures. For reference, honey can have a viscosity of around 10,000 cSt (centistokes), whereas waterâs viscosity at 20°C is 1 cSt (i.e. it has very little-to-no resistance to flow).
- The flash point is a key safety measure. It tells you about the lowest temperature at which the vapours from the oil will combust when exposed to an ignition source â so itâs very important to know!
- The pour point is the minimum temperature at which an oil has the ability to flow from a beaker. Itâs not the lowest operating temperature of the lubricant, but a good indication of its behaviour at low temperatures.
- USA Environmentally Acceptable Lubricant is an important internationally accepted environmental criteria.
Learn much more about lubricant Technical Data Sheets
I hope this blogpost has given you some idea of how to read and understand a lubricant technical data sheet. If youâd like to delve deeper into the topic, look out for my webinar coming soon where I go into each field in more detail.