Technology & Equipment
There is a crack in the "Renault" aluminum crank case. The wall thickness is about 2 mm.
The crack is thin and may be easily sealed up. Because of the coating brittlness the long cracks should be fixed before spraying. We do not expect high load to the wall at this object, so try to seal up without crack fixation.
Cut the crack edges.
Blast by abrasive Ê-00-04-16.
Spray K-20-11. To hasten the rate the temperature mode "4" was used.
The rate become higher with the outer side sealed. But…. Sprayed without a pauses thin wall has become hot and sudden click sounded. The coating has cracked. Unfortunately internal stresses in casted crank case appeared to be very high.
Cut the coating and repeat the process. Use less power now (temperature mode “2”) and make a pauses for the crank case cooling.
Everything is good now. Create the coating thickness above 2 mm for sure. Stiffeners may be sprayed across the crack line for the reliability.
The external view is not excellent, the restoration is obvious, but the crank case is ready for use.