If I'm hurt at work, does my employer have to claim it on Workers Comp?

[Bobbi Jo]

I work for a manufacturing company. They have purchased Workers Comp Insurance however, if I'm hurt on the job, they make me pay for the bills out of pocket and they reimburse me for the costs in order to keep their WC premiums low. Is this in any way fraudulant or illegal? I haven't been hurt but a coworker of mine was. How can I protect myself from this in the future?And how does filing through Workers Comp protect the employee? ------