Issue of c form

Dear Sir(s),  

We are tranders of heavy machinery items. We are purchasing some goods against c form. After purchasing the same we issued the same material to other company for prcessing and necessary modification. After that we will export the same.

Can we issue the C FORM to the dealer from whom we purchased the goods. I have one doubt that we are traders and we are not exporting the goods in same condition. We are exporting the same after modifications. .

Please help me in the above conditions. Please also tell the notifications and rules under VAt or CST Act. 

Thanks & regards

Ajay Singh