Grease Separation by Conical Sieve – sifting through the test

Introduction: Grease – More Than Just Slippery Business

As we delve into the world of grease, its hidden intricacies are not just about smoothly gliding surfaces – there’s much more than meets the eye. The core functionality and performance of a vast range of products, from industrial machinery to household appliances, hinge on a component that often escapes our notice – lubricating grease. To truly appreciate the importance of this hidden champion, it’s crucial to understand its composition and purpose.

Grease is primarily a combination of two elements: a base oil and a thickening agent. The base oil does the heavy lifting – providing the necessary lubrication to reduce friction and wear. The thickener, on the other hand, acts as a sponge, holding the base oil in place, a behind the scenes part ensuring the oil can perform at its best.

When the balance between these two components is disturbed, greases tend to separate, leading to a loss of lubricity, sub-optimal performance, and eventually, potential bearing failure.

This is especially important in high temperature applications where you need the grease to stay in place no matter what.

This is where the conical sieve method steps in, providing an invaluable tool for analysing and predicting grease behavior.

The Conical Sieve Method – When the Heat is On, Who’s Left Holding the Oil?

As things heat up, it’s time to find out if your lubricating grease is more than just a fair-weather friend. The conical sieve method will separate the contenders from the pretenders, just as it separates oil from grease.

Outlined under the ASTM D 6184 standard, the Conical Sieve Method is designed to measure the stability of lubricating greases under elevated temperatures. The test involves heating a pre-weighed grease sample in a conical sieve at around 100°C for approximately 30 hours. The separated oil is then weighed, with its mass expressed as a percentage of the original sample. This procedure effectively simulates oil separation during long term storage, especially high temperatures, offering insights into the grease’s performance and longevity.

Initially there is some weighing. You weigh the empty beaker to get initial (i) weight. Then you assemble the sieve apparatus and tare to zero. You then add the grease to get the grease weight (g). You then heat the whole thing for 30 hours in the oven at 100’c. Then you let cool, shake any excess liquid on outside of the cone on the beaker and weigh the beaker to get the final weight (f). The separation percent is the oil (f – i) divided by (g) x 100.

Understanding NLGI Grades – The Fine Line of Selection

In the world of grease, consistency matters. But is your grease too soft to stand up to the heat? Let’s sift through the facts as not all greases are suitable for this test.

Those having a penetratration softer than an NLGI No. 1 grade, do not qualify for this test. The NLGI grading system ranks grease based on its consistency – lower numbers indicate softer, more fluid greases, while higher numbers denote firmer variants. A thorough understanding of these grades can aid in selecting the perfect lubricating grease for your specific needs, ensuring optimal performance and efficiency. The 0, 00 and 000 grades look like gear oils by comparison and so because they do not stay in place and are fluids they are not suitable for the test.

How is this different to a drop point?

Before I bought the instrumentation for my lab I only ever used the drop point test and never really considered the conical sieve as an option. I was obviously unenlightened because as a combination is excellent at assessing temperature stability of your grease both in short and long term temperatures. The conical sieve method and the drop point test are both used to analyze the properties of lubricating grease, but they measure different things and serve different purposes.

The conical sieve method (ASTM D6184) tests for oil separation under static conditions at elevated temperatures. This test seeks to simulate the oil separation that occurs during long term storage. The grease sample is placed in a cone-shaped sieve and heated to 100’c for 30 hours. The amount of oil that separates and drips out of the grease is then weighed and reported as a percentage of the original grease sample.

On the other hand, the drop point test (ASTM D566) measures the temperature at which the grease changes from a semi-solid state to a liquid state under specific test conditions. The grease sample is heated at a steady rate and the drop point is the temperature at which a drop of oil falls from the test tube. This test gives an idea of the maximum temperature at which the grease maintains its structure.

While both tests give important information about the performance of a lubricating grease, they test for different characteristics and are used in conjunction to get a comprehensive understanding of a grease’s behavior under different conditions.

Oil Separation – When the Sieve Hits the Fan

In the hot and harsh world of mechanical bearings, you wouldn’t want your grease to start breaking under pressure. Let’s find out how the conical sieve method can help you avoid a potential slip-up.

By applying the conical sieve method, you unlock a new dimension of product selection and development. By predicting a grease’s stability under various conditions, you can make informed decisions on the most suitable lubricants for your system. This proactive approach can enhance quality control and streamline product development.

Grease analysis, despite being underutilized, holds the potential to revolutionize product performance. It empowers you to evaluate both new and used products, leading to optimal resource utilization. We are here to guide you through this complex terrain, offering expertise in grease analysis, product selection, and development.

Conclusion: Harnessing the Power of Grease Analysis

In conclusion, the Conical Sieve Method serves as a window into the secrets of your grease. Teaming up with us, you can leverage our expertise and create a winning narrative for your products and machinery. Embrace the hidden potential within your grease, and witness your products reach unprecedented levels of performance and satisfaction by testing your lubricants.

If you want to find out more about grease tests or analysis click the blue button below and contact us to discuss your needs.