Lubricants are the unsung heroes in mechanical systems. They reduce friction, disperse heat, and minimize wear and tear. High-quality lubricants extend equipment life and prevent mishaps.
Identifying the best possible lubricants for your application requires testing the key parameters that define quality, such as viscosity, thermal stability, corrosion protection, and more. In this guide, we will break down the key components and laboratory testing of lubricants, including how to ensure your lubricants meet the necessary requirements.
Lubricants play a crucial role in mechanical systems by mitigating friction, wear, and overheating—enhancing operational fluidity and longevity. Whether it's for industrial machinery, automotive engines, or everyday tools, the quality of lubricants is paramount. But what exactly constitutes a "quality" lubricant, and how do we test it to ensure it meets the required standards?
The quality of a lubricant is determined by its ability to perform its intended functions under varying conditions.
This measures a lubricant’s resistance to flow. Proper viscosity ensures the lubricant can form an adequate film between moving parts to prevent metal-to-metal contact. High-quality lubricants will retain the appropriate viscosity across a wide range of operating conditions, including pressure and temperature.
A high-quality lubricant will maintain its properties even at elevated temperatures without breaking down or losing effectiveness. This is crucial for applications where lubricants are exposed to extreme heat. A thermally stable lubricant resists the formation of deposits to protect surfaces from wear and tear.
Chemical breakdown can produce oxidation and lead to sludge and varnish formation. That can significantly impair performance and decrease equipment life. Stable lubricants minimize the formation of harmful compounds, interrupting the oxidation process. This is particularly important in applications where lubricants are exposed to heat and air for extended periods.
The right lubricant can prevent wear and tear on moving parts, extending the lifespan of machinery. This is crucial for equipment that operates under high loads, temperatures, or pressure. High-quality lubricants often contain anti-wear additives or extreme pressure additives. These form a protective layer on metal surfaces, reducing friction and preventing direct contact between moving parts even under harsh conditions.
A good lubricant protects metal surfaces from rust and corrosion, which can cause significant damage over time — forming a barrier between the surface and any elements like water, acids, or oxygen. There are several types of corrosion inhibitors, such as organic inhibitors (form protective films on metal surfaces), inorganic inhibitors (react with metal to form protective compounds), and vapor phase inhibitors (protect areas not in direct contact with the lubricant).
The ability to repel or suspend contaminants like dirt and water is crucial to prevent abrasive wear and corrosion. Poor resistance can introduce particles that increase wear, accelerate oxidation, and reduce machine efficiency. High-quality lubricants contain detergents and dispersants: detergents keep surfaces clean by preventing deposit formation, and dispersants keep contaminants suspended, preventing sludge. This is especially important in environments with high contamination, like industrial machinery.
To ensure optimal performance and longevity of machinery, laboratory testing of lubricants is mission-critical. You must have a firm understanding of any lubricant properties to ensure high performance.
The five key parameters of laboratory testing of lubricants are:
Viscosity
Viscosity refers to the resistance of a fluid to flow and is one of the most critical parameters in lubricant testing.
Viscosity measurements help ensure that the lubricant is at the appropriate consistency for a given application and that it is flowing smoothly through the machinery.
Oxidation stability
Oxidation stability refers to a lubricant's ability to resist oxidation, which can cause the lubricant to become acidic and lead to sludge and varnish build-up. Laboratory testing of lubricants measures stability, so you can feel confident in its performance.
Acid-base measurements
The acidity index is a measure of the amount of acid present in the lubricant, and it is determined through the Total Acid Number (TAN) test. A high TAN value indicates that the lubricant is acidic and needs to be replaced.
The Total Base Number (TBN) is another acid-base measurement that indicates the lubricant's ability to neutralize acids. A high TBN value denotes a lubricant's superior ability to neutralize acids and increase its lifespan.
Cleanliness
Cleanliness is also essential in laboratory testing of lubricants.
Particle contamination in the lubricant can cause premature wear and tear on machinery and lead to costly repairs. Particle count tests determine the number of particles present in the lubricant and help ensure that the lubricant is clean and free of contaminants.
Filterability testing
Filterability testing is another critical aspect of lubricant testing, ensuring that the lubricant is free of impurities and contaminants that can compromise its performance and longevity.
The filterability test determines the lubricant's ability to flow through a filter and is measured in terms of filterability time or pressure drop. The test helps identify any potential filter blockages that could cause machine failures.
Characterizing oils is key for QC, ensuring batch consistency, resolving production issues, and aiding product development. For users, it verifies that the lubricant meets industry standards, ensuring reliability and performance.
Background
With a reputation for quality and technical excellence made possible through continual investment in R&D, a multinational oil and gas company continues to innovate across its portfolio. The Latin American division of the company produces lubricants, oils, and greases that help maximize equipment efficiency, prolong vehicle life, and reduce downtime. These products deliver substantial savings to customers.
The company relies on high-performance analytical equipment for testing parameters such as base number (BN) and acid number (AN). BN shows a lubricating oil's potential for neutralizing acids caused by the condensation of engine combustion products.
The challenge
Due to increasing product demand, the company's routine testing needed improvement. Lab management chose an Excellence T9 for performing both potentiometric and KF titration.
This intelligent and powerful titrator makes complex tasks easy and efficient. It allows two titrations to run independently in parallel, enabling simultaneous volumetric and coulometric analyses. With the addition of a DO308 oven accessory, lubricant analysis speed and accuracy have significantly increased.
The solution
After consulting specialists from METTLER TOLEDO, the company confidently chose an Excellence D4 Density Meter. This device can accurately measure up to six decimal places with the same OneClick interface as their Excellence titrator.
With intuitive operation, routine testing has been made more efficient. LabX™ software links the company's titrator and density meter. It also enables LIMS integration for advanced traceability, increased speed, improved accuracy, and higher productivity.
The Density Meter Excellence D4 is an accurate, intuitive, and modular density meter for fast measurements in daily routines. With automatic temperature control and a real-time video view of measuring cells, you get an easy-to-use workflow with Once ClickTM operation for sampling, measuring, rinsing, drying, and SPOs.
The Titrator Excellence T9 is a versatile titrator for the most demanding applications. Providing modularity with the Excellence line, it supports InMotion automation and two simultaneous titration workflows — reducing analysis time by up to half. Automated decisioning can manage complex workflows with decision trees to lower human intervention and provide seamless solutions.