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Understanding Coefficient of Friction COF in Packaging Industry April 23,2019.

Flexible packaging is usually done on Vertical or Horizontal Form-Fill-Seal (FFS) machines in which the roll of film or laminate comes in contact with itself or other metallic /non-metallic components of the FFS machine. The contact generates friction which can inhibit the material to run properly on the machines and achieve desired production speeds.

There are two kinds of COF: static, the force needed to begin movement, and kinetic, the force required to maintain movement.  Generally, static COF is of greater concern for stacked or palletized items, while kinetic COF is used for roll films.  COF provides a relative indication of frictional characteristics and is routinely specified in substrates such as plastic films.

Controlling COF gives processors the ability to optimize performance and avoid problems in forming, transporting, and storing of packages.  Getting the COF right is mostly a process of qualifying a packaging product and then supplying this product at a consistent COF specification based on a given instrument and testing procedure.  It is important to remember that many converting variables cause COF to vary.  For example, this property is sensitive to application viscosity, coating weight, drying conditions, and environmental humidity.  So, running to proven standards ensures low waste and fewer field problems and returns.

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So how to measure packaging material COF and what kind of instruments will be used for this?

Measurements of frictional properties may be made on a film/laminate when sliding over itself or over another substance (usually stainless steel).

The amount of friction required to be overcome to initiate motion is called as the Static Coefficient of Friction and the amount of friction required to be overcome to continue the motion is called as the Kinetic Coefficient of Friction.

Applicable to : Plastic Film and Laminates.

Test Method : A sled weighing 200 ± 5 g is wrapped around with the test specimen and made to slide over a similar substrate or stainless steel surface with a speed of 150 ± 30mm/min. The initial and average drag force (in grams) is recorded and divided by the sled weight (200g) to calculate the static and kinetic COF respectively.

GBPI COF tester for plastic film,your best choice to help you measure your packaging material COF and help you improve your material production line.


This instrument can test the coefficient of friction of plastic film, thin sheet, paper and so on. It is applied to quality inspection organizations, drug control institutions, research institutes, packaging, thin film, food companies, pharmaceutical enterprises, personal care industry and so on.


GB/T 10006-1988, ASTM D1894-2014, ISO 8295-2004, TAPPI 816

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