Abrasive Flow Machining (AFM) is a secondary water jet machining process used to smooth, polish, radius, and remove cracks and burrs from hard to reach or internal surfaces of machinery, parts and products. It uses a polymer resin and abrasive materials, which are called media, in water under pressure to reach bends, cavities and edges.
AFM works on many different metal materials including steel, stainless steel, aluminum, zinc, brass, cast iron, titanium and nickel alloys as well as thermoplastics. The automotive, aerospace, food processing, pharmaceutical, medical, molding, marine and electronic industries use this finishing operation on a number of different products. Internal combustion engines in aircraft and automotive vehicles that use AFM to improve fuel economy, semiconductor equipment, surgical instruments, molds and dies for metal, glass and plastic product forming also often undergo abrasive flow machining to create shiny, smooth and even internal surfaces. The abrasive media and water that erode the product surface are forced through the cavity by a hydraulic system, which can have one or two-way flow directions.
The abrasive action created by AFM happens when the work piece, the product to undergo machining, is clamped between two media cylinders, one at the top and one at the bottom. The process is fully automated and computer controlled, thus greatly reducing labor costs, which are high if the process is manual because it is so time consuming and tedious. The hydraulic system starts at the bottom cylinder, and the water and media mix is shot at high speeds and pressure through the work piece. The water flow is either linear or comes out of both cylinders at the same time, thus decreasing the erosion process time. A temperature-controlled cooling jacket is used to keep temperatures consistent during the manufacturing process. AFM may be customized for specific results or when working with certain materials by using different grit sizes and types of resin and media, different viscosity and high or low flow rates and pressure. These factors are all determined by the material properties of the product being eroded, the desired finish and time constraints. Many abrasive flow machines are able to process many parts at once; they can also process multiple cavities and spaces of a single product.
