ISO 8295 Coefficient of Friction Plastic Film and Sheeting
- Peel, Tear, and Friction
- ISO 8295
- ASTM D1894
ISO 8295 is a standardized test method used for determining static (μ_s ) and kinetic (μ_k ) coefficients of friction of plastic film and sheeting. Plastic film is a widely used material in the packaging industry. Within the packaging industry the use of film can be separated into two categories: food packaging such as produce bags, carton liners, or meat seal wrap, and non-food packaging such as envelope liners or potting soil sacks. Outside of the packaging industry, plastic films are used for an assortment of products: trash bags, can liners, I.V. bags, construction liners, and other barriers. Thin films are also an important component of electric vehicle batteries, which is an industry predicted to experience explosive growth over the course of the next decade. The frictional properties of these films must be characterized and controlled to ensure the safety and functionality of the end product.
Separator films for electric vehicle batteries are being produced in increasingly high volumes and must undergo frictional testing as part of a robust material characterization process. These films are used to separate the anode and cathode in lithium-ion and other liquid electrolyte batteries, and are extremely critical to product safety. The most common material used for separator film is polyolefin, a polymer film that is strong enough to withstand the winding operation during assembly as well as uneven plating of lithium on the anode due to extensive use. Safer and stronger separator material more effectively prevents contact between the anode and cathode, while thinner material helps reduce the weight of each battery and improve energy density. Understanding the frictional properties of this polymer film can help ensure the material is being wound properly during assembly and will behave as expected under extensive use. Testing standards specific to electric vehicle batteries have not yet been established, so ISO 8295 is commonly used as a proxy standard to characterize the frictional properties of these materials.
Instron’s 6800 series frames are capable of data capture up to 5 kHz to ensure that all fast-changing test events are captured. Too low of a data capture rate may lead to missed force peaks and troughs, resulting in an inaccurate average strength value. For ISO 8295 testing we recommend a 6800 series single column frame equipped with a low force (5 – 100 N) 2530 series load cell depending on the expected frictional forces. This test requires the use of Instron's 2810-005 Coefficient of Friction fixture, which is specifically designed to meet the requirements of ISO 8295 and ASTM D1895.
|ISO 8295 Test Setup|
6800 Series Universal Testing System
Bluehill Universal Software
2530 Series Load Cell
|2810-005 Coefficient of Friction Fixture|
The ISO 8295 test method is used to investigate the static and dynamic frictional properties of film and sheet plastics when sliding against either itself or another material. This method is intended to be used for non-sticky plastic film and sheeting of up to 0.5 mm in thickness. To perform this test, the specimen is supported on a friction table consisting of a horizontal test table, a sled, and a driving mechanism which uses a pully to produce a relative motion between the sled and the test table. One piece of the specimen is attached to the table with double-sided adhesive tape while the other piece is secured to the sled in the same way. The test machine then drags the sled across the table at a constant rate of displacement, causing friction between the two pieces of material. The force is recorded, and test results are calculated. As always we suggest reviewing the full ISO 8295 standard to fully understand the testing requirements.
Instron’s 6800 controller can accurately measure forces down to 0.1% (1/1000th) of the 2580 series load cell's capacity, enabling the measurement of very low forces, potentially eliminating the need for multiple load cells. The lowest capacity 2580 series load cell is 500 N, meaning that it can maintain 1% accuracy from 0.5 N to 500 N. Instron’s 2530 series load cells can maintain 1% accuracy down to 1/250th of the cell’s capacity when used on a 6800 frame. The lowest capacity 2530 series load cell is 5 N, meaning it can maintain 1% accuracy from 0.02 N to 5 N. Forces beneath the lower limits of the 2580 and 2530 series cells can be measured, but Instron cannot guarantee 1% accuracy.