Abrasive flow machining (AFM) is a fine grinding process with rather low material removal rates. AFM is mainly used for polishing, deburring, and defined edge rounding and, due to the fact that a viscous carrier for the abrasive media is used, can be used to machine difficult-to-access cavities, inner contours, and undercuts in a reproducible manner [52]. Today AFM has found many applications in different industries such as automotive, aerospace, and mold and die making.
The machining process consists basically of the steps schematically described in Figure 6.53. Before processing, the abrasive medium is filled into the lower cylinder of the machine, after which the workpiece is placed into a specifically designed fixture and clamped between the upper and lower cylinder. The fixture has to fulfill several requirements: To clamp the workpiece safely in the media flow, to seal the system against leakage of the medium, and to ensure a controlled media flow in the closed system. Inside the closed system, the abrasive medium is first heated to working temperature and then pressed along the workpiece contours and cavities. Here, the design of the fixture plays an important role in controlling which parts of the workpieces are machined with what intensity. The machining process is repeated in an alternating up-and-down movement of the pistons until the machining time needed to obtain the desired result is reached.