Is this sentence correct ?

[Zoe2008]

We are asking the factory to see whether they can prepare more parts for your inspection. Will keep you posted

 

[David L.]

This is an informal type of business reply, so I presume you know the person pretty well. The grammar is correct and all that is needed is the Full Stop.
Some respondents may suggest omitting the "to see", so that the sentence would be "... asking the factory whether they can prepare..." However, as an informal communication, adding the 'to see' gives that part of the sentence the meaning 'we are asking the factory to look into the possibility as to whether they can prepare more parts...'