Cooper Instruments & Systems Model 7i Professional Force/Torque Indicator - Manual (Page 25)

Model 7i Digital Force / Torque Indicator User’s Guide
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12 COEFFICIENT OF FRICTION
The 7i, with an appropriate force sensor, can determine the static and kinetic coefficients of friction (COF)
between two materials through the Averaging and peak tension capture functions. The process for
determining COF requires dragging a block of a known mass (usually 200 g) over a surface at a constant
speed. The force required to do so is divided by the weight of the block. For example, a force of 100 gF
divided by 200 g equals 0.5 COF.
Although many COF testing applications require a sled weight of 200 g, the indicator allows the user to
change the sled weight to comply with other requirements. To modify the sled weight, select COF from
the menu. The display appears as follows:
Available sled weight settings:
100 – 1000 g
Motorized test stands and suitable fixtures are recommended for COF measurement applications.
Recommended products: ESM301 test stand and G1086 COF fixture
13 CUSTOM UNIT
A user-defined unit of measurement may be configured for special applications. A base unit is specified,
along with a multiplier, and 5-character name. Typical applications:
1. To measure the torque produced by pressing on a lever in a mechanical assembly, configure
the multiplier based on the length of the lever, thereby converting a unit such as N into Ncm.
2. To measure the pressure produced by a circular compression plate on a foam sample,
configure the multiplier based on the area of the plate, thereby converting a unit such as lbF
into psi.
To access this feature, select Custom Unit from the menu. The display appears as follows:
CUSTOM UNIT
Enabled
Base Unit: lbF
Unit Name: UNITx
Multiplier
1.000
COF
Enabled
Sled Weight Unit
g
Sled Weight
200.0