the importance to learn english

When you decide to study for enginner, you have think about the matemathics and others subjects, but we don't study english like a tool, one very important tool.
If true that we stusy english in one or other way, but always we study for talk to someone like in here, but Technical english, what can we say about that....
When you work in a factory the technical english it's very difficult to understand, and almost the machine's manuals are write in english.
But in that moment you don't know what means bearing, regrind, resaw, insulation, or other words like that.
it's necesary study technical english if you want to b a enginner.