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AFF process is employed for
Deburring
Radiusing
Polishing
Removing recast layer
All of the above
The Abrasive Flow Finishing (AFF) process is employed for all of the following purposes:
1. Deburring: AFF can be used to remove burrs and sharp edges from workpieces, improving their safety and functionality.
2. Radiusing: It can also be used to create or enhance rounded or radiused edges on workpieces.
3. Polishing: AFF is capable of achieving a high degree of surface finish and can be used for polishing applications to improve the appearance and smoothness of workpiece surfaces.
4. Removing recast layer: In processes like EDM (Electrical Discharge Machining), a recast layer of material is often formed on the surface of the workpiece. AFF can be employed to remove this recast layer and reveal the desired surface underneath.
So, the correct answer is: All of the above.
In AFF the media extruding pressure ranges from
0.70-22 MPa
15-60 MPa
0.5-10 MPa
24-38 MPa
In Abrasive Flow Finishing (AFF), the media extruding pressure typically ranges from 1,000 to 10,000 psi (pounds per square inch) or approximately 7 to 70 megapascals (MPa). The specific pressure used can vary depending on the application and the desired finishing results. Different workpiece materials, geometries, and surface finish requirements may require different pressure settings within this range. Adjusting the extruding pressure allows for control over the material removal and finishing action during the AFF process.
Replaceable inserts in AFF tooling is made of
Copper
Mild steel
Teflon
Brass
The replaceable inserts in Abrasive Flow Finishing (AFF) tooling are typically made of a resilient and flexible material such as elastomers (rubber-like materials) or polyurethane. These inserts are designed to hold and shape the abrasive media as it flows through the workpiece passages. They allow the abrasive media to conform to the specific contours and surfaces of the workpiece being finished, ensuring that the desired surface finish is achieved. The flexibility and resilience of these inserts are essential for their effectiveness in the AFF process. When they wear out or become damaged, they can be easily replaced to maintain the performance of the AFF tooling.
The base material in AFF process is made up of an organic polymer and
Paraffin oil
Hydrocarbon gel
Grease
In the Abrasive Flow Finishing (AFF) process, the base material is typically made up of an organic polymer mixed with abrasive particles. This mixture forms a semi-viscous, abrasive media that is used to remove material from the workpiece surfaces. The organic polymer acts as a carrier for the abrasive particles and provides the necessary viscosity and flowability to the media. As the media is forced through the workpiece passages under pressure, it effectively removes burrs, sharp edges, and other surface imperfections while also achieving the desired surface finish. The choice of the organic polymer and the type and size of abrasive particles can be customized to suit specific finishing requirements.
Which type of media is used to finish large holes
Stiffest
Soft
In the Abrasive Flow Finishing (AFF) process, different types of media can be used to finish large holes or bores, depending on the specific requirements of the application. One common type of media used for finishing large holes is a specialized extrusion tool with a flexible, abrasive-filled polymer or elastomer that conforms to the shape of the hole.
The media used for finishing large holes in AFF typically consists of abrasive particles mixed with a carrier material. The carrier material is often an organic polymer or elastomer, which provides the necessary flexibility and flowability to reach and finish the interior surfaces of the hole. The abrasive particles within the media work to remove material and achieve the desired surface finish.
The specific type and composition of the media can vary depending on factors such as the size and shape of the hole, the material of the workpiece, and the desired finishing results. Customized extrusion tools and media formulations may be used to address the unique requirements of finishing large holes effectively.
Profile of surface after AFF process is
Unidirectional
Bidirectional
The profile of a surface after the Abrasive Flow Finishing (AFF) process can be either unidirectional or bidirectional, depending on how the process is carried out and the specific goals of the finishing operation.
1. Unidirectional Finish: In a unidirectional finish, the abrasive media flow is primarily in one direction along the surface of the workpiece. This can result in a finish with directional patterns or striations, which may be desirable for certain applications. Unidirectional finishes are often achieved by controlling the flow direction of the abrasive media during the AFF process.
2. Bidirectional Finish: In a bidirectional finish, the abrasive media flow occurs in multiple directions, typically back and forth or in a crosshatch pattern. This approach can result in a more uniform and isotropic surface finish, where the directional patterns are less pronounced. Bidirectional finishes are achieved by changing the direction of media flow during the process.
The choice between unidirectional and bidirectional finishes depends on the specific surface texture and appearance requirements of the workpiece. Some applications may benefit from a unidirectional finish for aesthetic or functional reasons, while others may prefer a bidirectional finish for its uniformity. The process parameters and media selection can be adjusted to achieve the desired surface profile, whether it is unidirectional or bidirectional.
Higher viscosity of the polishing media in AFF process results in
Higher surface roughness
Lower surface roughness
In the Abrasive Flow Finishing (AFF) process, the viscosity of the polishing media plays a significant role in determining the surface roughness of the finished workpiece. The general principle is as follows:
Higher viscosity of the polishing media tends to result in **lower surface roughness.**
Here's why:
1. Media Flow Control: A higher-viscosity polishing media flows less easily, and it tends to adhere more closely to the contours of the workpiece. This results in better control over the abrasive action. The media can be directed precisely to the areas that need polishing, reducing the likelihood of over-removal and creating a smoother surface.
2. Smoothing Effect:The higher viscosity allows the media to remain in contact with the workpiece surface for a more extended period, which helps in smoothing out surface irregularities and achieving a finer finish.
3. Reduced Agitation:High-viscosity media is less likely to agitate and create turbulence during the process, which can lead to a more uniform and controlled finishing action, resulting in lower surface roughness.
However, it's essential to strike the right balance because excessively high viscosity can also lead to challenges in media flow, making it difficult to reach certain areas of the workpiece. The viscosity of the polishing media should be chosen carefully based on the specific requirements of the application and the desired surface finish.
AFF can produce dimensional tolerance of
± 0.005 mm
± 0.01 mm
± 0.009 mm
The dimensional tolerance that can be achieved with Abrasive Flow Finishing (AFF) can vary depending on several factors, including the specific process parameters, the geometry of the workpiece, and the characteristics of the abrasive media used. However, a common range for dimensional tolerance achievable with AFF is typically around ± 0.01 mm (0.001 cm) or 10 micrometers.
So, the most accurate option among the ones you provided is:
± 0.01 mm
What type of cavity is employed in orbital AFF
Partially through cavity
Through cavity
Blind cavity
In orbital Abrasive Flow Finishing (AFF), a "through cavity" is employed. A through cavity is a cavity or passage that extends completely through the workpiece, allowing the abrasive media to flow through it and treat both the entry and exit sides of the cavity. This configuration is often used in AFF to finish internal passages, holes, or bores that have an open path for the media to flow in and out.
In contrast, a "blind cavity" would refer to a cavity or passage that does not extend all the way through the workpiece but ends at some point, preventing the media from flowing completely through it.
Orbital AFF is commonly used to finish workpieces with complex internal geometries, and the use of through cavities ensures that the entire interior surface of the cavity is treated for consistent and uniform finishing.
Minimum limit of hole diameter can be machined in AFF is
0.2 mm
0.8 mm
0.01 mm
The minimum limit of hole diameter that can be effectively machined using Abrasive Flow Finishing (AFF) can vary depending on several factors, including the specific equipment, media, and process parameters. However, AFF is generally capable of finishing holes with a diameter as small as 0.8 mm (800 micrometers) or larger.
So, the option "0.8 mm" is a reasonable minimum limit for hole diameter in AFF. Achieving consistent and effective results in holes smaller than this diameter may pose challenges due to the size and flexibility of the abrasive media and tooling used in the process. Smaller hole diameters may require specialized equipment and media formulations.
The flexibility of AFM process is
High
Low
Moderate
The flexibility of the Abrasive Flow Machining (AFM) process is generally considered to be **high.**
AFM is known for its versatility in finishing complex and intricate geometries, including internal passages, contoured surfaces, and irregular shapes. It can adapt to various workpiece materials and sizes, making it a flexible choice for a wide range of applications. The process parameters, such as abrasive media type, viscosity, and pressure, can be adjusted to tailor the finishing action to specific requirements, resulting in a high degree of flexibility in achieving desired surface finishes and edge profiles.
In AFF maximum machining takes place when there is
Minimum restriction
Maximum restriction
In Abrasive Flow Finishing (AFF), maximum machining or material removal typically takes place when there is **maximum restriction** within the workpiece passages or cavities.
When the abrasive media encounters higher resistance or restriction within the workpiece, it exerts more force and pressure on the workpiece surfaces. This increased pressure enhances the abrasive action, leading to more effective material removal and finishing. Maximum restriction can occur in areas of the workpiece with tight clearances, narrow passages, or complex geometries where the media flow is constrained. In such cases, the abrasive media is forced to work more intensively on the surfaces, resulting in increased material removal and surface improvement.
To achieve precise control over material removal and surface finishing in AFF, engineers and operators often carefully design and control the restriction points within the workpiece to optimize the process for specific applications.
Material removal rate in MRF is proportional to
Applied Pressure
Relative velocity
Both
The material removal rate in Magnetorheological Finishing (MRF) is primarily proportional to the **applied pressure** and, to some extent, the **relative velocity** between the workpiece and the finishing tool. However, the applied pressure plays a more significant role in determining the material removal rate.
MRF is a precision finishing process that uses a magnetorheological fluid (a fluid containing magnetic particles) to perform material removal. When an electromagnetic field is applied to the fluid in the presence of the workpiece, the magnetic particles in the fluid align to form an abrasive layer, and material is removed from the workpiece as it interacts with this abrasive layer.
The applied pressure determines the contact force between the abrasive particles in the MRF fluid and the workpiece surface. Higher pressure results in greater contact force and, consequently, a higher material removal rate. Therefore, increasing the applied pressure typically leads to a more significant material removal rate in MRF.
The relative velocity between the tool and the workpiece can also influence material removal but to a lesser extent. A higher relative velocity can enhance the cutting action and the efficiency of material removal, but it's not the primary factor that determines the material removal rate in MRF.
Volume concentration of CIP in MR fluid is in the range of
30-50%
10-20%
50-80%
The volume concentration of carbonyl iron particles (CIP) in Magnetorheological (MR) fluid typically falls in the range of **10-20%**. MR fluids consist of a carrier fluid (usually oil-based) and suspended magnetic particles, such as carbonyl iron or other iron-based particles. The concentration of these magnetic particles in the fluid can vary depending on the specific application and the desired rheological properties of the MR fluid. However, in most MR fluid formulations, the concentration of magnetic particles is within the 10-20% range to achieve the desired magnetic responsiveness and rheological behavior.
Additives are used in MR fluid to
Achieve stability
Reduce redispersibility
Achieve settling
Additives are often used in Magnetorheological (MR) fluids primarily to **achieve stability** and enhance their performance. These additives help maintain the stability of the MR fluid by preventing particle settling and aggregation when the fluid is at rest. The stability of MR fluids is crucial to ensure consistent performance in applications that require controlled and predictable rheological properties, such as damping and stiffness control in devices like MR dampers (magnetorheological shock absorbers).
The use of additives can also aid in achieving other desirable characteristics, such as preventing oxidation of the carrier fluid, controlling viscosity, and improving the overall performance and longevity of MR fluids. Additives are carefully selected and formulated based on the specific requirements of the MR fluid for a particular application.
With increasing magnetic flux density, change in surface roughness in MRAFF process
Increases
Decreases
In the Magnetorheological Abrasive Flow Finishing (MRAFF) process, the change in surface roughness is typically influenced by the magnetic field strength, which affects the behavior of the magnetorheological (MR) fluid and the abrasive particles within it.
As the magnetic flux density (magnetic field strength) increases in MRAFF, it generally leads to **increased abrasive particle concentration and alignment** in the MR fluid near the workpiece surface. This can result in a more aggressive abrasive action on the workpiece surface.
Therefore, with increasing magnetic flux density, the change in surface roughness in MRAFF **increases** as the abrasive particles become more concentrated and aligned, resulting in a more effective material removal and finishing process.
Under the application of external magnetic field MR fluid acts as
Shear thickening fluid
Shear thinning fluid
Under the application of an external magnetic field, Magnetorheological (MR) fluid typically acts as a **shear thickening fluid.**
In the presence of a magnetic field, the magnetic particles within the MR fluid align along the field lines, forming particle chains or structures. These aligned particles resist flow and create a more solid-like behavior in the fluid, causing an increase in its apparent viscosity. This increase in viscosity is known as shear thickening. As a result, the MR fluid becomes stiffer and more resistant to deformation under shear forces.
This property of shear thickening in MR fluids is exploited in various engineering applications, such as magnetorheological dampers and clutches, where the viscosity increase can be controlled and utilized for damping and torque transmission.
Which abrasive particle is generally used to finish optics in MRF process
Aluminium oxide
Cerium oxide
Boron carbide
Cerium oxide is generally used as the abrasive particle in the Magnetorheological Finishing (MRF) process for finishing optics. Cerium oxide (CeO2) is known for its polishing and fine abrasive properties, making it suitable for achieving high-quality optical surfaces. It is often used to remove fine scratches, improve surface smoothness, and achieve the desired optical quality in various optical components such as lenses, mirrors, and prisms.
Main stress responsible for material removal in MRF process is
Shear stress
Normal stress
In the Magnetorheological Finishing (MRF) process, the main stress responsible for material removal is **shear stress**.
MRF is a precision finishing process that uses a magnetorheological fluid (MR fluid) containing suspended abrasive particles. When an external magnetic field is applied to the MR fluid between the workpiece and the finishing tool, the magnetic particles align into chains or structures. As the tool moves relative to the workpiece, these aligned particles create shear stress at the interface between the abrasive particles and the workpiece surface. This shear stress causes abrasion and material removal, resulting in the desired surface finish.
While normal stresses may also exist in the process due to the contact between the tool and the workpiece, the primary mechanism for material removal and finishing in MRF is shear stress generated by the magnetic field-induced alignment of abrasive particles.
During synthesis of MR fluid, what type of liquid is responsible for the continuous phase
Organic
Inorganic
During the synthesis of Magnetorheological (MR) fluid, the **continuous phase** is typically an **organic liquid.**
MR fluids are composed of two main components: a carrier fluid and magnetic particles (often iron-based). The carrier fluid, which serves as the continuous phase, is typically an organic liquid such as mineral oil or silicone oil. This organic liquid provides the necessary viscosity, fluidity, and stability to the MR fluid.
The magnetic particles are dispersed within the continuous phase, forming a suspension. When exposed to a magnetic field, the magnetic particles within the MR fluid respond by aligning along the field lines, which is a key feature of MR fluids and enables their unique rheological behavior.