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October 10, 2005
Favorite Analogies #2: Traction on rollers and cars
Continuing my on-going themed entries on favorite analogies of web handling. Here's #2
The traction between a web and roller is like the grip of a car tire and the road.
More car weight creates more tire/road friction.
More tension creates more web/roller friction.
The ability to exchange force withoug slipping will be a function of the coefficient of friction of the tire/road (and web/roller).
(continued...)
A tire/road interface can be lubricated by water, oil, snow, ice, or gravel.
A web/roller interface can be lubricated air, coatings, or debris.
Fluid lubrication will increase with speed, decrease with web tension/car weight, increase with area of contact, and increase with fluid viscosity.
Lubrication can be reduced by tire treads or roller roughness / grooving.
Losing traction means loss of driving, braking, and turning control of the car or web.
Slippage will occur when the applied force exceed the traction available (car and web).
Demand for slippage is greatest when it comes from two directions, such as braking while in a turn (using some traction to oppose centrifugal forces), or steering a web where both lateral web bending forces and machine direction anti-roller drag and inertial forces are applied.
MORE? Of course there are. Please reply with your thoughts.
Posted by Tim Walker at October 10, 2005 09:07 AM
