Hemming is an incremental joining technique used in the automotive industry, involving bending the flange of an outer panel over an inner panel to join two sheet metal panels. In the roller hemming process, a robot guides a small roller across the flange to fold the sheet onto itself or another sheet. Roller hemming is superior to press hemming and tabletop hemming for complex-shaped parts and is typically used in low-volume automotive production lines. For higher production volumes, such as 120 jobs per hour (JPH), press hemming or tabletop hemming is generally preferred due to their efficiency.
However, roller hemming can be adapted for high-volume production by combining multiple hemming stages into a single turntable cell. This innovation eliminates the load and unload time at each station, resulting in a 20% increase in hemming robot utilization. Additionally, the process reduces the number of robots and the required floor space while maintaining the same cycle time compared to traditional multi-stage hemming setups. By eliminating station transfers, which take 14 seconds, and using turntable rotation, which takes only 5 seconds, the additional 9 seconds can be utilized for hemming, resulting in a 20% increase in hemming robot utilization. Employing two robots per station, this approach provides an additional 18 seconds of hemming time.
Consequently, the need for gripper robots is eliminated, leading to a reduction of five robots in total. This streamlined process significantly enhances efficiency and cost-effectiveness in high-volume automotive production. By eliminating 5 robots and 2 grippers, the total initial cost savings would be approximately $500,000, with an additional annual maintenance cost savings of about $60,000.
Keywords: Roller hemming, Turntable, Hemming cycle time