Xinrui Alice’s Answer
Personally when I started working as a mechanical engineer, the part that surprised me turned out to be my favorite part of my job, which is working cross-functionally with other teams. Rarely is a great design born in isolation. The products that I work on have electrical components and software components, which means the mechanical design directly impacts electrical and software performance, so working with Electrical/Software Engineers is key. In addition, if the product were to be sold, then working with Marketing and Human Factors is also important to make sure that not only does the product works well, what it does well is actually useful to the end customer. As Derek mentioned in another answer, theoretical designs on the computer can look great, but it cannot be sold as a product if if cannot be produced. This means it's important to work with Operations and Manufacturing Engineers. These interactions have been very educational in my career and not something I expected fresh out of college.
I only do some mechanical work, but I'll at least give a start here. It seems obvious in hindsight, but I didn't appreciate how tightly paired mechanical design was to manufacturing processes. When I was taught CAD, it was almost taught as an end in itself...which usually works for 3D printing.
But in applied engineering, the most clever design folks tend to model with the constraints of molding/extrusion/stamping/etc already in mind. Functional parts are important for concept exploration, but it's hard to bring something to market unless it can be made with cheap manufacturing processes.
Aside from that, the best mechanical engineers I've worked with were masters of the less flashly skills...dimensioning drawings, effective tolerancing, designing parts whose critical dimensions can be easily measured, poka-yoking everything that's hand assembled, paying sufficient attention to the interfaces between parts, etc. There's also a lot on optimization via simulation (both for manufacturing and the stresses the finished product will undergo), but that's not a skillset I can speak to.
- Hardly using any of the equations I learned in school
- How long the simplest things can take
- How many things can go wrong on a project
- How bad some managers are at managing people
- A lot of testing designs & parts
- How often I'd be expected to work extra hours
- How differently companies operate from each other--and how unaware the management is of these differences
Most of the problems you work in school have a fairly black and white answer. It will break or it won't. There is x amount of stress in this area of the part. You get the idea.
All of that gives you a mere foundation upon which you will use judgement over a given problem. Hey, that primary stress you calculated did not compensate for manufacturing deficiencies or tolerancing. Now the high stress are is on the other side, where there was some pitting because rain got to the metal in transport. We need a hole in this part but can't get at it with our drill press; can we use a mag drill, a hand held drill or a plasma cutter? We ran out of grade 8 bolts, what is the best alternative that will provide the clamping force profile we need? I have to design a platen for a big machine, should I use a casting, a weldment or should I bolt together something? The cell that fabricates a particularly hot product is overloaded; can we adapt a cell with excess capacity to make it... or should we move other work from the overloaded cell to make the hot product.... or should we farm it out?
The jobs with simple answers are few... and in retrospect, I would have become bored very quickly if I had found one.