A polymer micro cold forging process was investigated. This method, derived from polymer solid-phase forming, resembles more the metal-forging method than the standard thermoplastic molding protocol. A micro-forging die set was designed and fabricated and a series of cold forging experiments were carried out with varied process conditions, including forging speed, forging pressure, and dwell time. High-aspect-ratio microchannels. were fabricated on polytetrafluoroethylene (PTFE) substrates. The dimension of replicated channels was found to be consistent from shot to shot. Owing to instantaneous elastic recovery, the channel has a width about 30% smaller than that on the die. The final channel size is contingent upon the forging process conditions, as well as upon the post-recovery process. Upsetting experiments of PTFE cylindrical samples were carried out to study the fundamental issues on dimensional recovery so as to predict and consequently control the dimensional changes in polymer cold forging. (C) 2004 Society of Plastics Engineers.