This letter should be a formal letter.
Ice cream factory ,
Sub: Requesting a permission to visit your factory .
I am a student of the hounarable college. We've got a project work on the machanism of ice cream factories . I along with my friends formed a team to complete the project.
Sir, i request you to grant us permission to visit your factory and please help us in completing our project . we will be very thank full to you .
Yours sincerely ,