The coefficient of friction (COF) in packaging film is a measure of the resistance to sliding between two surfaces, one of which is the packaging film itself. It is an important parameter in the packaging industry as it can affect the performance of packaging materials during manufacturing, filling, sealing, and transportation.
There are two types of coefficients of friction commonly used in packaging:
- Static COF (μs): This represents the initial resistance to start the motion of two surfaces relative to each other. It is measured when the packaging film is not in motion, just before it starts to slide. A high static COF can make it difficult to start the movement of packages on a conveyor belt, for example.
- Kinetic COF (μk): This represents the resistance to maintain the motion of two surfaces sliding past each other once they have started moving. It is measured when the packaging film is already in motion. A high kinetic COF can result in difficulties in controlling the speed and stability of packages on a conveyor or during handling.
The coefficient of friction in packaging films can be influenced by various factors, including:
- Surface roughness of the film material.
- Surface treatments or coatings applied to the film.
- The presence of additives or slip agents in the film formulation.
- The type of materials that the film comes into contact with, such as other packaging materials, conveyor belts, or handling equipment.
Manufacturers and packaging engineers often test and specify the COF of packaging films to ensure they meet the requirements of the specific packaging application. Different applications may have different requirements for static and kinetic COF values depending on factors like the packaging process, the type of products being packaged, and the equipment used.
The COF of packaging film is typically measured using specialized testing equipment, such as a coefficient of friction tester. It’s essential to control and optimize the COF to prevent issues like film slippage, misalignment, or difficulty in handling during the packaging process.
International Standard : ASTM D1894