How to measure friction

Friction is the resisting force that arises when one surface slides, or attempts to slide, over another. It plays a crucial role in our daily lives, sometimes essential (e.g., enabling movement) and other times a limitation (e.g., reducing the efficiency of machines). Friction is commonly measured in packaging materials, shaving gels, and cosmetic products. There are two types of friction: static friction (the force required to initiate movement between two surfaces) and kinetic (dynamic) friction (the friction which is created between any two surfaces when they are in a moving position).

Measuring friction helps understand how materials will perform in real-world applications, such as how easily packaging films slide against one another or how much effort is required to move one part over another in machinery. Friction measurements, including the coefficient of friction (COF), help manufacturers improve product performance and optimise processes by reducing unwanted friction.

Friction measurements using a Texture Analyser are valuable in industries like packaging, automotive, and manufacturing, where controlling friction is critical. Below are key applications:

• Packaging film friction testing: Evaluating the friction of packaging films to ensure efficient processing on packaging machines by measuring the force required to slide the film over a flat surface to determine its COF. Lower friction indicates smoother material handling, while higher friction could cause jams or increased machine wear.
• Textile industry friction testing: The friction between fabrics can affect how they behave during cutting, sewing, or wearing. Slippery fabrics like satin or silk exhibit low friction, making them easier to move, while rougher fabrics like wool generate higher friction and may resist movement.
• Paper and cardboard coefficient of friction testing: Assessing the COF between paper or cardboard surfaces by measuring the force required to slide one surface over another, critical for packaging and printing.
• Automotive brake pad friction testing: Testing the frictional properties of brake pads by measuring the force needed to move the pad against a rotating brake disc to ensure optimal friction performance.
• Footwear sole material friction evaluation: Evaluating the slip resistance of footwear soles by measuring the force required to move the sole material across a surface to assess its COF.
• Cosmetic product texture analysis: Measuring the frictional properties of cosmetic products like creams and lotions by assessing the force needed to spread them on a skin-like surface to evaluate texture and spreadability.
• Material handling and conveyor belt friction testing: Testing the frictional properties of conveyor belts by measuring the force required to move a material sample across the belt to ensure smooth product transport.
• Sports equipment grip friction analysis: Evaluating the grip friction of sports equipment handles, such as tennis racket grips, by measuring the force required to slide the material against a ball.
• Metal-to-metal friction testing: Friction between metal surfaces is important in manufacturing processes such as stamping, moulding, or machining. Higher friction can lead to material wear and increased energy consumption, while lower friction improves efficiency. Measuring the COF between metal surfaces used in machinery by assessing the force needed to slide one metal surface over another to evaluate wear and lubrication.

In these examples, a Texture Analyser applies controlled forces/distances to measure the frictional properties of materials and products, ensuring product quality, process efficiency, and compliance with friction standards across industries.

In a typical friction test, one material or surface is moved across another while the force required to overcome the resistance (friction) is recorded.

Horizontal Friction System

• Temperature: Temperature can significantly affect friction measurements by altering the mechanical properties of materials and influencing the behaviour of lubricants or surface films.
• Humidity: Humidity levels can impact friction measurements by affecting the formation of moisture films on surfaces, potentially leading to changes in adhesion and lubrication.
• Speed of motion: The speed at which surfaces move relative to each other during testing can influence friction measurements, as some materials exhibit different frictional behaviours at varying speeds.
• Geometry of test specimens: The shape and dimensions of test specimens can affect the distribution of forces and contact area during friction testing, potentially influencing the measured friction coefficients.
• Alignment of surfaces: Proper alignment of test surfaces is crucial for accurate friction measurements, as misalignment can lead to uneven force distribution and inconsistent results.
• Consistency in preparation: Maintaining consistent sample preparation methods, including cleaning procedures and surface treatments, is essential for reproducible friction measurements across multiple tests or specimens.

The Stable Micro Systems Texture Analyser stands out in optimising friction measurements through its comprehensive approach and specialised features. Equipped with specially designed Horizontal Friction System which provides accurate measurement of friction properties such as static and kinetic friction.

Exponent Connect software enhances accuracy by capturing force-distance-time data at 2000 points per second, providing highly detailed graphs for in-depth analysis. In contrast, lower data collection rates, often found in alternative equipment, can result in compromised accuracy and missed information, impacting the reliability of the results.

The Texture Analyser can also incorporate acoustic analysis for multi-dimensional insights. Its versatility allows for testing a wide range of materials, from cosmetics to packaging material.

Backed by Stable Micro Systems' expertise in method development and data interpretation, makes it the ideal choice for industries seeking to refine product formulations and maintain quality standards in friction testing.