On a philosophical note, I can tell you, when a human interacts with another human, there will be a transaction. The transaction can be good, bad or ugly considering the mindset of the individuals. This is common for all functions, roles and responsibilities and note unique to HR alone. If the problems relate to equipment, machinery etc, they can be set right by engineers ie human beings. However, if the problem relate to another human being, our creator ie. Almighty cannot come and set them right. We humans have to do it ourselves. So long as humanity is there, conflicts cannot be avoided. However, it is up to the persons concerned at all levels to create an environment where the conflicts can be avoided or reduced by installing proper mechanisms. There should be sacrifice from both sides without any egos ! Instead of looking at the problems, as problems, look at them as opportunities to improve the situation, service, or performance.
Best wishes