Hampus Johansson works as an Application Development Engineer at Erteco. In this story, he was tasked to identify the cause and solve the problem of cracking in a marine propeller inner hub component, which was made from glass-fiber reinforced plastics. The cracks tended to occur while the blades were rotating upon high-load scenarios, which affected the part quality and prevented it from functioning properly.
The analysis using Moldex3D confirmed that the flow patterns resulted in severe weld lines. They occurred at the same crack position where the blades transferred great loads to the hub upon heavy acceleration. This area was the thinnest section, and weld lines drastically decreased its strength. To reinforce the hub, the tape from Ems Tape Technology (ETT) that consisted of an extruded matrix of polyamide with carbon fibers was positioned at that weak area. Moldex3D helped to indicate that an increase in mold temperature and higher packing pressure that neutralized part shrinkage could stop the tape from delaminating from the matrix, since they could slightly increase the time span for the melt front temperature to stay above melting temperature at that weak spot during the packing phase to generate perfect bonding between tape and polymer. Sensor nodes were used at different locations between tape and hub to monitor temperature and pressure profile.
- Optimized process conditions
- Perfect bonding between reinforcing tape (ETT) and polymer
- Eliminated crack at the severe weldline location at the thinnest section of the hub
- Huge cost saving by successfully implementing ETT to reinforce the hub