DYNAMIC COEFFICIENT OF FRICTION
In 1835, A Morin proposed that, because the force resisting the start of sliding was obviously not the same as
the force required to maintain sliding, two different coefficients of friction were operating. The first is the SCOF,
which is the relative force (H/V) required to start motion in a body at rest. The second coefficient is the dynamic
coefficients of friction (DCOF), which is relative force required to maintain motion in a sliding body. Generally,
SCOF produces a higher number than DCOF, because it takes more force to initiate a sliding motion than to keep a
sliding object in motion.
Foreign nations such as Europe and Australia only measure DCOF for surface testing.
DCOF AND THE BOT-3000
Until recently, the goal was to achieve and maintain a .5 Static Coefficient of Friction (SCOF) on a dry floor surface.
However, laboratory and field research have led to new, emerging and more practical benchmarks, since it is now clear
that slips occur most often on wet floors in dynamic "in motion" environments.
The Binary Output Tribometer or BOT-3000 is a portable robotic device for both laboratory and on-site testing of
dry and wet static and dynamic coefficient of friction. Since the BOT is an automated unit that can be calibrated in the field,
user error or variability is minimized.
The BOT meets ASTM's rigorous precision and bias requirements. It is also recommended by a major insurance carrier,
and other expert groups.
STATIC COEFFICIENT OF FRICTION (SCOF) is the ratio of the horizontal force needed to start an object moving
to the vertical force pressing an object to the surface.
DYNAMIC COEFFICIENT OF FRICTION (DCOF) is the ratio of the horizontal force needed to keep an object moving
to the vertical force pressing an object to the surface.
Kenneth Fisher, Preventing Slip and Fall: Mastering Wet DCOF Measurement