In abrasive jet machining (AJM), solid and hard abrasive grits accelerated by pressurized air jet are allowed to impinge the work surface to erode material in the form of tiny metal particles. A mixture of eroded metal particles and used abrasive grits flow out of the machining zone. So there always exists a chance that some of the abrasive grits remain stick to the work surface and don’t come out from the machining zone. Such phenomenon enhances when work material is soft and ductile (like wood, plastic, leather, foam, aluminum, copper, etc.).
Why AJM should not be used for machining soft and ductile materials?
While machining ductile materials by AJM, the hard abrasive grits may get embedded on the soft machined surface. This hampers cut quality as well as properties and appearance of machined surface. While cutting deep slots or holes, these embedded abrasives can restrict further erosion and thus degrading trend in material removal rate (MRR) is observed. There also exist high chances of side cutting instead of cutting at bottom. Moreover practically it has been observed that MRR for machining brittle materials is usually higher than that of ductile materials. Due to the above reasons, AJM is not recommended for soft and ductile materials; however, preferred for non-conductive brittle and hard materials.
Results of using AJM for machining soft and ductile materials
- Presence of abrasive on machined surface
- Degradation of surface finish
- Change in surface properties
- Poor surface appearance
- Increased kerf width (because of side cutting)
- Lower material removal rate (MRR) for deep cutting
- Book: Nonconventional Machining by P. K. Mishra (Narosa Publishing House).