Diesel Engine Parts started refining the "Fusion" welding process over three decades ago. Fusion welding is the process of removing the cracked and damaged areas from cylinder heads and then using modern metal casting technologies to return those areas to like new condition. After the fusion welding/recasting process, and a stress relieving process, the cylinder heads are reassembled and tested for integrity. This process restores like new performance at a cost significantly lower than purchasing new components.
Another great advantage is the significant environment benefit from the reuse/recycling of these castings.
The typical "Fusion" welding and machining processes performed by DHPS on cast iron cylinder heads are described below. The Fusion welding process can also be used to repair many other types of cast iron castings.
Cleaning
Cylinder heads come into our warehouse where they are inspected and disassembled.
Once disassembled, all parts are cleaned in our high efficiency cleaning ovens. This process burns away grease and carbon deposits and is much more environmental friendly than acid cleaning.
To finish the cleaning process the cylinder heads are then placed into a steel shot machine. This process removes any residual rust, dirt and grime, leaving the heads bright and shiny.
Finally, to ensure there is no residual steel shot trapped in the cylinder heads, they are placed in a tumbler to remove any remaining steel shot. This process also removes rust particles, machine cuttings and any other foreign debris.
Welding and Reassembly
Cylinder heads that are cracked, pitted or damaged in any way that re-machining cannot fix are "fusion" welded, returning them to a like new condition.
After cylinder heads have been fusion welded and stress relieved they go through our machining process.
After machining, cylinder heads are moved to our production line for internal parts installation.
Finally, once the internal parts are installed, valve seats and injector holes are machined to ensure valve seat concentricity, and proper fuel injector alignment.
Finishing Up
To ensure that each cylinder head is "true" and has the proper surface finish, all the mating surfaces are measured, then machined as required. The RMS of the sealing surfaces is restored to new specification to ensure correct gasket retention, and a no leak seal.
Finally, each head is pressure tested to confirm the integrity of water jackets, valve seating, and any other air or fluid passageways.