arunmrao said:
A toothbrush was used just yesterday to remove the metal debris in the space shuttle power systems.
Metal debris is a serious issue and requires constant attention. Not even super critical applications like manned space system hardware is immune. First, I think arunmrao meant the space station (ISS) and not the space shuttle. It's great to see that the EVA crews have been taught to check threaded fasteners closely for metal debris before re-installing them. Metal chips can easily cause a fastener to seize up, and the worst possible situation in orbit is a fastener that gets stuck partially installed. It cannot be removed and it does no good for carrying loads. The ISS solar arrays have had previous issues with generating metal debris, most notably
the rotary joint trundle bearings.
Speaking of the space shuttle and machining debris left behind, here's an incident I recall from a few years back (when I was working on the shuttle program). During a routine radiographic inpection of the cooling tubes on one of the SSME nozzles a broken drill bit was found inside. Never heard if they figured out where it came from, but if that chunk of drill bit had passed through a turbopump it would likely have caused catastrophic damage, not to mention the multi-million dollar costs for repairs and possible mission termination.
Coming up with a process for removing/isolating the metal debris generated during finish machine operations in morkman's assembly is only half of the task. The other half of the job, which is equally important, is establishing a reliable method for verifying the process is resulting in acceptable levels of cleanliness. The best approach, as suggested by mfgenggear, would be to first use masking/plugs/guards/etc. to confine the debris to areas where it can easily be removed. A post machining flush with some type of liquid that is compatible with your assembly materials would probably be more effective at removing any remaining metal chips than compressed air. You might also take a look at the possibility of making changes to the shape of your parts to assist with debris removal, and also to eliminate any crevices/ledges/pockets/etc. that would trap small bits of debris. Lastly, don't forget to consider whether your final machining operation will leave behind any edge burrs that may break free during service. And if so, how will you remove them.
Sorry for the long response. But ensuring cleanliness is definitely a subject that many people fail to appreciate the importance of. Sadly, in my career I've seen many instances where it has caused serious problems. Hope this helps.
Terry
