Advice
From my experience with test Engineering, I'd say get to know everyone. If you're looking for an answer, somebody on site will have it, you just need to know who. Even if you don't work with them, get to know them, as they can teach you new lessons or just enhance your intern experience in ways you didn't realize. Most importantly, get to know the people in the shop. Get to know the machinists and spend time working with them, especially if your projects are changing how they work. And most importantly, smile and say hi to them, it gets relationships started that are life changing.
From my experience working with production, if you take an opportunity like this to work on a shop floor, get to know engineering as well. Since I worked with engineering prior to moving to production, I was able to talk to both production and the engineering folks on both sides of any issue. Being able to see both sides and understand both sides is primarily where I gained the most experience this rotation. I saw how a lack of effective communication easily leads to frustration. This especially fits with my previous comments from my last rotation - get to know people, as many as you can. Take the time to have conversations with them since they'll teach you more than just job skills, but also life skills.