Help please!

I don't claim to know anything about it, but would guess heat dissipation and wear would be factors that drive Area.

I've never heard or read of it being a factor in developed braking force calcs. If it is in practice its probably small and outside predictability with stiffness of pad supports being more significant?

I think I'd go on about it like I knew what I was doing, but a web search for the terms

"pad area" brake | braking force

will turn up a lot of information and disinformation for you to sort thru.

I'm no expert on brakes themselves, but I've dealt with friction and wear a fair amount in other contexts. It depends upon the accuracy with which you are working. The friction coefficient in most cases is dependent on the area and the normal force. As examples, think about how hard a rug is to slide across the floor when it is laid out flat compared to when it is rolled up, or why higher performance cars have wider or taller tires with bigger contact patches. If you're trying to calculate your braking force very accurately, you would probably need to account for that variation and the area of the brake pad would be relevant. If you're doing a more basic analysis, you can probably ignore it. In that case, the area of the brake pad would be irrelevant.

Wear is even trickier than friction. At the simplest level, the volume of wear material is assumed to be proportional to the normal force times the distance traveled. In that case, the area of the pad would be inversely related to the thickness of the wear layer lost on the brake pad itself. When you start to dig into it farther, the product of the pressure (inversely proportional to your area) and the velocity is often very important in determining the rate of wear. It all depends on the materials you're using.

Jerry Steiger Tripod Data Systems "take the garbage out, dear"

I do not design braking systems, but can say that for low to moderate forces the resultant frictional force is independant of the force per unit area. Other factors that affect the resultant coefficient of friction are surface finish, surface adhesion, surface deflection, humidity and contamination. Defining low to moderate force for a particular application is another problem.

Kman

As a general rule of thumb yes.

The assumption is that the force is distributed more or less evenly and that there are no regenerative effects as there would be in a band brake or drum brake.

YES, YES and YES!!!!

It does not matter what the area is!!!!!!!!!!!!!!!!!!! It is only effected by a normal force and friction coefficient

EXAMPLE: if you have two boxes on the table, one is very small and another is very large, both weigh 20 lb Which one is easier to push?

Answer: the SAME (it would require the same force to push it)

Mike

Doesn't that model (Coulombic friction) assume that you have rigid bodies? That may be an invalid assumption for brake pads.

Interesting thought - have to ponder that one.

WT

However, it is also true that in general sliding friction is less than static friction. Usually by a factor of 2.