CMS Bulkheads

The bulkheads are some of the most critical components on our rocket. Our tanks are made from thin pipe sections and 3 bulkheads, all welded together. We machine our bulkheads in house and all 3 involved some interesting techniques.

The bulkheads are 6" in diameter made from 6061 aluminum. The first operations were done on the lathe for facing passes and then outer diameter roughing and finishing. We attempted to bore out the inside bowl, but, with the boring bar tooling that BIDC has, there was quite a lot of chatter. The remaining ops, including boring out the bowl and any other operations, were done on a 5-axis CNC mill. The ballnose mill ended up giving a far better surface finish than the boring bars we had. 

Many of the surfacing passes with the ballnose mill were simultaneous 5-axis, so pretty complicated toolpaths. Custom soft jaws were made for the bulkheads as to not crush or leave any marks from something like a 3-jaw chuck.  Additionally, the upper bulkhead had required clocking features from one side to the other, so we had to get creative and use 2 drills with the same shank diameter, a parallel, and a magnetic dial indicator, to manually clock the bulkhead in the machine. The end results were some very nice looking bulkheads, that also passed hydroproof tests up to 635 psia, which is 1.5x our maximum expected operating pressure.