Methods and apparatuses for bonding polymeric parts are disclosed. Specifically, in one embodiment, the polymeric parts are bonded by plastically deforming them against each other while they are below the glass transition temperatures. A method includes: placing a first polymeric part in contact with a second polymeric part; and plastically deforming the first polymeric part and the second polymeric part against each other to bond the first polymeric part to the second polymeric part. Additionally, during the plastic deformation, a temperature of the first polymeric part is less than a glass transition temperature of the first polymeric part and a temperature of the second polymeric part is less than a glass transition temperature of the second polymeric part.