Abstract: The fracture-splitting mechanism and conditions were discussed and the key techniques and working procedures such as the material selection, machining of cracking notches, directed fracture separating and assembling bolts in required torque were presented. A fracture-splitting machine that can provide backpressure in cap of connecting rod was developed and fracture-splitting processing for car engine connecting rods was investigated numerically and experimentally. The results show that the right design in notch location and geometry and the satisfactory precision for notching reduces fracture loads effectively, the backpressure is of benefit to splitting quality, a right ratio of splitting force to backpressure force brings a perfect fracture face in the case of applying instantaneous load to hole in the big end of connecting rod.

Key words: connecting rod, fracture splitting, key technique, cracking notch