What is abrasive flow machining? Types, Application

Abrasive flow machining is also called extrude honing. It is an inner surface finishing process that uses abrasive-laden fluid that is applied through a chamber that gets the cleaning process. Fluid has a viscous nature that provides a smooth finish for inner surfaces that are difficult to approach. This process is applied on rough surfaces, removes errors, and also helps to make a larger size of chamber. In this post we will cover details for the abrasive flow machining process and related factors.

What is abrasive flow machining?

Abrasive flow machining (AFM), also calleed abrasive flow deburring and also known as extrude honing. It is an inner surface finishing process where abrasive-laden fluid flows in the working component.

Fluid has a viscous nature with dough-like features. This process makes rough surfaces smooth and helps to remove burrs, polishes surfaces, and also removes materials.
This process is best to use for inner surfaces, holes, and slots and helps to approach parts of material that are difficult to access.
It is not preferred for larger stock removal functions since it has a low material removal rate. It has had importance in different processes since 1970.

Abrasive Flow Machining Working

Abrasive-filled fluid passes through materials at the time of the extrusion honing process. Elevation of the surface is removed when making a connection with an abrasive fluid, like sandpaper removing wood splinters.
Hydraulics move fluid at the time of the process, and viscous material is converted into a mold of the accurate shape of the materials.
Abrasive flow machining works in a two- or one-way flow process.
The working piece is created through back-and-forth motion of a semisolid abrasive medium. The process is abrasive in the extrusion area, and it has constrained flow.
Abrasive media hone the surface gently and simulate the lapping process.
This process helps to make accurate shapes of materials like soft aluminum, nickel alloy with hard design, carbides, and ceramics.

Abrasive Flow Machining Equipment

• The abrasive flow machine comes with two medium chambers, hydraulic rams, a fixture that holds the working component, and a clamping system that manages all components.
Some machines are used for loading different abrasive media and also have features for setting the pressure applied for extruding the medium through the working component.
They can work manually or using an automated CNC machine. A machine that is made for handling high production and devices for cleaning of parts, unloading and reloading stations, and media heat exchangers also exists.

Abrasive Flow Machining types

One-Way AFM

One-way AFM performs a unidirectional function and moves the abrasive medium in one direction over the working component. It is easy to configure as compared to multi-directional machines.
Abrasive medium extruded on a single cylinder medium on the working component and after that on the receiving chamber.
Media flows in in one direction, and abrasive grains affect the surface in a certain direction.
It is an easy and low-cost process but not effective for providing smooth finishing for complicated designs.
It is used for light polishing of basic inner surfaces.

Two-Way AFM

Two-way AFM is a commonly used machine, and it provides oscillating features. It provides good finishing for complicated designs.
In this process media move back and forth in two directions through working components with double-pressure medium cylinders.
The dual operation of this abrasive medium machine flow helps abrasive grains to work for cutting surfaces at different angles, resulting in smooth material removal and a good surface finish.
It provides a good surface finish and material removal due to dual direction.
It is good to use for complicated designs and intersecting holes.
It provides good polishing and radiusing with that used for polishing of turbine blades and also part of the aviation industry.
It also performed the finishing of medical implants and surgical tools.

Orbital AFM

Orbital AFM performs motion through the motion of working components and tools. It provides an extra abrasive process and also good control for the process.
abrasive medium traversed over the working component and extra orbital motion that is provided to the working component.
This movement provides nonlinear features for the track where abrasive medium moves over the surface which provides repetition and work for certain locations.
It provides control for the surface finishing process and increases smoothness for surface finishing for handling complicated parts.
Orbital AFM is good to use for finishing components where a nonuniform layout exists.
It has limitations that needed complex instruments and also needed special fixtures.
It is also part of mold polishing and dies where complicated patterns exist.

Multiple-Passage AFM

This method is used for larger working components that need to be processed with different patches for abrasive mediums in sequence or parallel combinations.
It comes with a design of tools that helps the abrasive medium to move on different paths or different materials at the same time.
Tooling helps to process the same components at the same time and also handle different parts of larger components in series.
It is used for bulk volume manufacturing and provides high efficiency and different components.
It also manages larger designs. Tooling design is complicated and high cost.

Extrusion Honing

Extrusion honing is a special type of AFM that works on bore finishing and bore sizing. It is used for inner cylindrical surfaces. In this process high-viscous and abrasive polymer medium moves through the bore in high-pressure conditions.
medium overcontrolled flow Make flexible honing tools that provide good surface finishing through removing materials and have an accurate inner dimension diameter.
Extrusion honing is performed in 2-way tooling features.
It provides good bore roundness with proper internal diameter, having a good surface finish.
It removes micro burrs and is a low-cost option for honing small and larger diameter bores.
It is used for performing accurate cylindrical internal designs and needed special tools for holding working components and medium.
It is used for finishing hydraulic valve bodies and sleeves.

Abrasive Flow Machining Features

The AFM process easily polishes inner passages and complicated designs that are not easy to access with normal tools.
The thickness of deburring is self-deforming and provides a uniform connection with the working component surface and also easy removal of different materials. It also provides a smooth finish on different angles and designs.
AFM provides the same controlled radius for edges that are important for managing stress and also increases the working life of components.
It removes burrs that exist after the machining process and removes any premature components and overall affects working life. Minimizing stress also increases durbality of the component.
AFM did not generate any heat, so no thermal distortion exists and it did not affect the material’s features.
It operated on different alloy metals such as steel, aluminum, and ceramic materials, and also on plastics.
It provides a good surface finish; deburring provides good flow and low ear and also good performance.
AFM is also performed in an automated way for high volume and provides high efficiency for production and reduces working costs.

Limitations of Abrasive Flow Machining

AFM machines are costly processes, and abrasive mediums are also used for limited times since they have consumable features.
It is a finishing process with a low rate of material removal, especially compared to other machining processes, and it is not good to use for larger material removal processes.
It takes some time and also needs high optimization, like a viscous medium or a type of abrasive with proper dimensions.
It needed to use special types of tools for accurate abrasive medium flow through complicated passes that could not be performed without expert engineers.
AFM is good to use for inner finishing passages but not effective for larger flat external surface designs that are good for conventional processes.
AFM is not good to use for accurate edge processes that need zero radius.