Coefficient of friction describes the resistance to movement between two surfaces. Measurements are typically made with the material tested against itself, as results can be influenced by surface finish and contamination.

Testing can measure both:

  • Static coefficient of friction – the force required to initiate movement between two surfaces
  • Dynamic coefficient of friction – the force required to maintain movement between the surfaces

Slip coefficient is the reciprocal of coefficient of friction:

Slip coefficient = 1 / coefficient of friction

Friction and slip can be important for materials used on high-speed printing, converting and packaging lines, including papers and cartons. In other applications, such as sacks, bags and corrugated cases, a higher coefficient of static friction may be desirable to help resist sliding when stacked.

Standards and accreditation

Smithers measures static and dynamic coefficients of friction using recognised methods including:

  • STM D4917 for paper
  • TAPPI T 549 for uncoated writing and printing papers
  • TAPPI T 816 for corrugated and solid fibreboard
  • BS ISO 15359 for paper and board

Smithers is ISO 17025 accredited for testing to ASTM D4917.

Talk to our experts about your paper or board material, application and the friction or slip performance you need to evaluate.

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