Obviously this doesn’t go for all companies out there, but:
At my company HR is so far removed from the actual employees that asking HR would be a waste of time because they honestly don’t know. They just weed out the ones that are obviously unqualified and funnel the rest to the designers to look over then the designers send HR back a list of people to call in for interviews. That being said, if you can get HR to help you to get in touch with an actual designer where you want to apply they’ll probably be more than happy to talk about what they do on a day to day basis, what kind of designer they’re looking for, and possibly most importantly how to make a good first impression with the interviewer at that particular company. Surprisingly I had some success with being an internet stalker on LinkedIn while trying to get in touch with a designer at a particular company while I was in school, but there’s a fine line between “taking initiative and showing interest” and “creepy”. Be polite and don’t pester them if they don’t respond.