SPROCKET:-Transmission:

Sprocket is an gear like element used in chain transmission system. The best example of it is in Bicycles, in chain mechanism.Now, the chain transmission system is pree common, and designer would need to model it on CAD software with perfect involute curve in its teeth. Here below, I made 30 teeth sprocket, with perfect involute curve in its teeth. You can go to 'http://www.gearseds.com/files/design_draw_sprocket_5.pdf' to see how I made it on my CAD software.

Also, If you are using Pro/E to model the sprocket with above steps, use construction lines to make final involute curve. I think that's the best way to make it by Pro/E, as if you make the curve by depending on regular lines, when you will trim them, the left involute curve will ask for dimensions again. Do it like this below:

Manufacturing: Now Don't even think, that you can make it on VMC's without cam. These are generally manufactured on Hobbing machines, using a sprocket hobb cutter. The choice of using cutter depends upon no. of sprocket teeths and size, which in turn depends upon selection of chain, eg. chain no.25,35,41,40 etc. Here below, is the picture of typical sprocket hobb cutter!