Will is hardly ever a purely modal verb. It generally combines its modal meaning with the function of an auxiliary expressing futurity.
The modal verb will expresses volition, intention on the part of the speaker, or insistence.
#1. Volition, intention.
In most cases, this meaning is rendered in Russian by emphatic intonation, but sometimes the verb хотеть is used. It is used with all persons but mostly with the first person.
“What is this? Who is this? Turn this man out. Clear the office!” cried Mr. Fang. “I will speak,” cried the man. “I will not be turned out…” (Dickens)
Besides, since happiness is irrevocably denied me, I have a right to get pleasure out of life: and I will get it, cost what it may. (E. Bronte)
Tell Mr. Osborne it is a cowardly letter, sir, a cowardly letter — I will not answer it. (Thackeray)
Very often will is used after the conjunction if in conditional clauses where it retains its modal meaning, that of volition.
You may laugh if you will but I was sure I should see her there. (E. Bronte)
The modal verb will is used in polite requests.
Will you have a cup of tea?
Will you give me a piece of bread, for I am very hungry? (Ch. Bronte)
#2. Persistence referring to the present or to the future.
“Don’t tell me.” “But I will tell you,” repeated Sikes. (Dickens)
She begins to act very strangely. She will not speak, she will not eat; finally she dies. (Maugham)
It is also used in speaking about lifeless things when the speaker is annoyed at something and speaks about a thing or a phenomenon of nature as if it possessed a will of its own (there is an element of personification here).
It’s no use trying to open the door, it will not open.