Hamsters are real chewers. They need to keep their teeth in good condition and to wear them down as they constantly grow. Chewing is necessary to a hammies health. Unfortunately, some hamsters become fixated on chewing cage bars which can be really annoying. This is usually the result of boredom, or being in a cage that is too small. Even such little animals need tons of room to run about and investigate as they would in the wild. Toys are essential. Also every hamster needs wood sticks and a stone chewing block to gnaw on.
If you hamster continues to bar chew, the best way to keep him is in a large aquarium with a ventilated lid, or in a hamster home with plastic sides and few bars. Be careful though! Hamsters are escape artists and you need to be sure the home is secure. A hamster at large can do a lot of damage to your home furnishings!