My last post was about the machining of our “low pressure” pistons. Our combustion pistons start out with a very different kind of fabrication process: Direct Metal Laser Sintering (DMLS). It is a kind of 3D printing. Believe it or not, finding a short, entertaining video about DMLS is difficult. So instead please enjoy the least annoying video about the process I could find:
Here is what the parts look like just after printing.
This had to be printed because there are some internal cooling passages inside of them that traditional machining cannot make. In mass production this is handled by making them in two parts and then friction-welding the two halves together. For just two prototypes, that is not economical, thus we went with DMLS. There is still a lot of machining and grinding to do before the pistons are done. Eventually, they will look like this:
Edit: Here is a finished piston next to one of the blanks!
Finished piston next to printed blank.
Austin Jones at J.H. Benedict has been very nice to send us several pictures of our 4340 steel exhaust pistons throughout the manufacturing process. They are almost finished. There is still some grinding to do and some machining on the crown. You can see they did the turning operations first on the lathe, and then machined out the inside of the piston. Bushings for the wrist pin will be machined and ground out of a bronze alloy and pressed in later.
4340 steel billet for the piston beginning the process.
First turning operations for the piston are complete.
Machining processes on the piston.
Roughing out the inside of the piston on the mill.
The piston is nearing completion! Lands and grooves are still to be ground, and the crown is still to be machined. Bushings will be pressed in later.