Hello
Our company is joint company ( which is made up of some factories and a holding company) , our question is that, whether is it possible to use one separate Dynamics for each factory or just one Dynamics suits our demands???
You can go with one…
For more detials look into microsoft site : http://www.microsoft.com/en-us/dynamics/products/ax-overview.aspx
You need to contact a partner - who can understand your company structure and your requirements and who can propose the suitable dynamics product(NAV / AX).