Abrasive flow machining - GIF and videos

Abrasive flow machining. Also known as abrasive flow deburring or extrude honing.

<video controls autoplay loop>
<source src="https://s3-us-west-1.amazonaws.com/hmt-forum/extrude_honing_automotive_part.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>

48-second video of extrude honing for an aerospace part:

https://www.youtube.com/watch?v=E5_iIaVMZcg


17-second video demonstrating the process:

https://www.youtube.com/watch?v=JMygwSIqrN0

And I believe this is the original patent, granted to the Extrude Hone Corporation in 1974: US Patent #3,819,343. The basic formula for the abrasive listed in the patent is guar gum, boric acid, and borax.

https://s3-us-west-1.amazonaws.com/h...ing_patent.jpg

More: https://en.wikipedia.org/wiki/Abrasive_flow_machining

That's interesting that the abrasive medium is just pumped through and out. In the mid 1980's the NASCAR guys were doing this to induction systems, heads and exhaust systems and sometimes coolant passages in the block and they would build jigs with reservoirs on both ends of the flow with a reversible pump and flow back and forth in both directions.

What an interesting idea. I am assuming for this to work the opening needs to be pretty good in the first place since otherwise you will only exacerbate any defects.

The abrasive removes irregularities so yes there must be some flow. Casting flash for example or a badly shaped internal passage all get removed and blended like a wizard port and polish.

I ran a machine in 1980? that had 2 rams pushing abrasive charged "Silly Putty" thru artificial heart valves to remove the EDM finish and polish the insides. Went up and down, fixture held 10 ringlike valves.
It worked great until one of the hydraulic hoses broke, blew oil all over in seconds.

The putty was contaminated with oil and went to crap.