Not discouraging you.

But I would'nt try this kind of a thing as a project even for my own factory. Better would be to go in for a professional product in this regard. There are so many available - for any size of factory.

This issue of time keeping and deciding salaries and incentives is a very sensitive issue and better play safe. Or if you are keen to somehow do it - try it out EXTENSIVELY before putting it on line.

Raghu