"As we want to" in scientific writing

Solution 1:

What the author wants or wishes is of little interest to the reader of the paper. For such papers the fewer words used to get the idea across the better. I certainly approve of it as a way of making your writing easier to read and more friendly but you could get by without it and should do in a scientific paper.

Rather try; "To focus on the assembly process..." or "In order to focus on the assembly process..."

Unless your friend can point to a style guide I think it is just an opinion. A good opinion but only that. Warner's English Grammar describes what type of usage is appropriate for various communications, personal and professional.