This paper presents a comprehensive study of sub-THz (sub-142 GHz) radio propagation and channel characterization in indoor factory environments. The research involves extensive measurements at 142 GHz in four factories, covering a wide range of distances and conditions. Over 75,000 spatial and temporal channel impulse responses were collected from 82 transmitter-receiver (TX-RX) locations, including both line-of-sight (LOS) and non-LOS (NLOS) scenarios. The study employs steerable directional horn antennas and measures TX-RX distances ranging from 5 to 87 meters. The results show that low RX heights (0.5 meters) experience an average path loss increase of 10.7 dB and 6.0 dB in LOS and NLOS conditions, respectively. Channel enhancement measurements using a rotatable large flat metal plate as a passive reflecting surface (PRS) demonstrate significant omnidirectional path loss reduction, with a mean reduction of 6.5 dB. The paper also compares channel characteristics at different antenna heights, highlighting the impact of proximity to the floor in cluttered factory environments. Finally, the study provides the first statistical channel characterization and path loss modeling for industrial scenarios at sub-THz frequencies, emphasizing the potential for ultra-broadband factory communications in the 6G era.This paper presents a comprehensive study of sub-THz (sub-142 GHz) radio propagation and channel characterization in indoor factory environments. The research involves extensive measurements at 142 GHz in four factories, covering a wide range of distances and conditions. Over 75,000 spatial and temporal channel impulse responses were collected from 82 transmitter-receiver (TX-RX) locations, including both line-of-sight (LOS) and non-LOS (NLOS) scenarios. The study employs steerable directional horn antennas and measures TX-RX distances ranging from 5 to 87 meters. The results show that low RX heights (0.5 meters) experience an average path loss increase of 10.7 dB and 6.0 dB in LOS and NLOS conditions, respectively. Channel enhancement measurements using a rotatable large flat metal plate as a passive reflecting surface (PRS) demonstrate significant omnidirectional path loss reduction, with a mean reduction of 6.5 dB. The paper also compares channel characteristics at different antenna heights, highlighting the impact of proximity to the floor in cluttered factory environments. Finally, the study provides the first statistical channel characterization and path loss modeling for industrial scenarios at sub-THz frequencies, emphasizing the potential for ultra-broadband factory communications in the 6G era.