Luckily, smoothing out and polishing the surfaces of your casting isn’t as complicated as it once was. We can reach the desired finish as part of the "all in" experience through a technique known as abrasive flow machining. In this process, a chemically inactive and non-corrosive media is pressed through the components, grinding the channels and smoothing the surface for a perfect surface finish and edge conditions.
"For our requirements at ACTech, conventional abrasives only worked to a limited extent," explains Alexander Seidel, an employee specializing in raw part finishing at ACTech. "With AFM, we can finally grind internal complex contours and barrels and make the surfaces in them better. The bottom line for the customer is that the media - air, water, oil, etc. - can flow better through the component."
So, how exactly does the process work?
It begins with a choice of abrasive - coarse, medium, and fine - all made of silicon carbide, a viscoelastic mass with abrasive particles of different strengths and sizes. This choice depends on the nature of the part that needs to be machined: the smaller the opening, the finer the abrasive.
The process begins with a one-time setup, lasting anywhere between 60 and 90 minutes, depending on the part. To do this, the compound is poured in and made pliable by pushing it back and forth. Afterward, the part is screwed onto the necessary adaptor and prepared for the actual AFM process.
"This takes only a few minutes and is carried out at between 20 bar for a fine abrasive and 36 bar for a coarse abrasive," adds Alexander.
To complete the process, we remove the abrasive with a wire, compressed air, or spatula with as little loss as possible. The part is then washed with a combination of a basic alkali and 50°C water, which dissolves any residual abrasive and removes the oily film that has formed.