ABRASSIVE FLOW MACHINING

PRESENTED BY

Prateek jain(11375)

Rahul bhagat(11374)

Anand kumar(11370)

Ashish somvanshi(11373)

Piyush kumar(11377)

ABRASSIVE FLOW MACHINING

It is a process of polishing and smoothening

internal surfaces.

The abrassive media is flown across the surface to

be super finished either in a single direction or in 2

direction and is extrude through w.p,theirby

finishing the w.p and smoothening the surfaces.

CLASSIFICATION OF AFM MACHINE

One-way AFM

Two-way AFM

Orbital AFM

ONE-WAY AFM

One-way flow AFM processing pushes abrasive

media through the work piece in only one direction,

allowing the media to exit freely from the part.

TWO-WAY AFM

The typical two-way flow AFM process uses two

vertically opposed cylinders to extrude an abrasive

media back and forth through or around passages

formed by the work piece and tooling . Abrasive

action occurs wherever the media enters and passes

through the most restrictive passages

ORBITAL AFM

Surface and edge finishing are achieved by rapid,

low-amplitude, oscillations of the work piece relative

to a self-forming elastic plastic abrasive polishing

tool.

The tool is a pad or layer of abrasive-laden elastic

plastic medium(similar to that used in two way

abrasive flow finishing),but typically higher in

viscosity and more in elastic.

PROPERTIES OF AFM

Deburring, radiusing, and polishing are performed

simultaneously in a single operation

AFM can produce true round radii even on complex

edges

Reduces surface roughness by 75 to90 % on cast

and machined surfaces

AFM can process dozens of holes or multiple

passages parts simultaneously with uniform results

APPLICATION OF AFM

Automotive

Aerospace

Medicine

Dies and Molds

AFM IN AEROSPACE INDUSTRY

Improved surface quality

Enhanced high cycle fatigue strength

Optimized combustion and hydraulics

Increased airflow

Extended component life

AFM IN AUTOMOTIVE INDUSTRY

Enhanced uniformity and

surface quality of finished

components

Increased engine performance

Increased flow velocity and

volume

Improved fuel economy and

reduced emissions

Extended work piece life by

reducing wear and stress

surfaces

AFM IN DIES AND MOLD INDUSTRY

Reduced production costs

Increased production throughput

Enhanced surface uniformity, finish and cleanliness

Improved die performance and extend life of dies

and molds

AFM IN MEDICAL INDUSTRY

Eliminate the surface imperfections where

dangerous contaminates can reside

Improved functionality, durability and

reliability of medical components

Enhanced uniformity and cleanliness of

surfaces

Extended component life

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 3, Issue 2 ,February 2013)

Jose Cherian, Dr. Jeoju M Issac

Research Scholar, Karpagam University, Eachanari Post, Coimbatore-641021

Professor, Department of Mechanical Engineering, MA College of Engineering Kothamangalam, Kerala, India.

Gov K, Eyercioglu O, Cakir MV. Hardness Effects on Abrasive Flow Machining.

Journal of Mechanical Engineering. 2013; 59: 626- 31.

Eyercioglu O, CAKIR MV, GOV K. Influence of machining parameters on the surface integrity in small-hole electrical discharge machining. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. 2013.

Reaserch Papers

RESEARCH PAPER 1

Effect of Process Variables in Abrasive Flow

Machining

• International Journal of Emerging Technology and Advanced Engineering

• Website: www.ijetae.com (ISSN 2250-2459, Volume 3, Issue 2, February 2013)

• Jose Cherian, Dr. Jeoju M Issac

1. Research Scholar, Karpagam University, Eachanari Post, Coimbatore-641021

2. Professor, Department of Mechanical Engineering, MA College of Engineering Kothamangalam, Kerala, India.

PROCESS MODELLING AND

OPTIMIZATION Williams and Rajurkar developed a stochastic model of AFM generated surfaces by

Data Dependent systems (DDS) methodology.

Estimated the ratio of surface roughness peak height (RZ) to the centerline average

surface roughness value (Ra) by DDS methodology and found to be between 1.4 and

2.2 micrometers for the AFM process.

A large wavelength corresponds to the main path of the abrasive while the small

wavelength is associated with the cutting edges.

They proposed an expression for estimating the abrasive grain wear and the number

of active grains(Cd). The estimated value of Cd can be used as a cutting life criterion

for abrasives.

For small number of cycles, its value should remain fairly stable but with more and

more processing, the abrasive particles may fracture and thereby increasing the Cd

value. The downturn of Cd value indicates that the medium has been absorbed too

much abrasives and needs replacement.

Carried out simulation of finished surface profiles and material removed considering

the interaction of abrasive grain with work piece material.

Proposed a mathematical simulation model to determine the characteristics of the

medium flow during finishing and its experimental verification.

They reported that a linear relationship exists between shear stress acting on the

surface and the layer thickness of material removed.

EXPERIMENTAL RESULTS

Fig 2 Fig 3 Fig 4

FIG 8 , 9 AND 10

RESEARCH PAPER 2

This paper conducted on the finishing of difficult to

machine materials like Ti6Al4V.

The influence of the AFM process on Ti6Al4V

workpieces were investigated.

The results show that the white layer formed during

WEDM is successfully removed by AFM in a few

cycles for each workpiece.

ABOUT TI6AL4V

Ti6Al4V displays high strength, corrosion and heat

resistant properties.

Are commonly used in high temperature

applications such as turbine blades and rocket

engines.

It is considered more difficult to finish using

conventional techniques (grinding, lapping, etc.)

than other metallic materials.

EXPERIMENTAL WORKS

The experiments were performed on Ti6Al4V.

The specimens were cut from the slabs by using wire electro discharge machine (WEDM) to 5x10x20 mm as shown in Fig.

The WEDM parameters kept constant for all specimens to ensure the pre-surface characteristics of the specimens.

Table1

Surface roughness values of the specimens before

AFM.

Table2

Physical, mechanical and thermal properties of

Ti6Al4V.

THE ABRASIVE FLOW MACHINE

In this study a two-way AFM machine that has two

vertically opposed chambers was used (shown in

Fig.).

The machine contains of a main frame, hydraulic unit,

electronic control unit and heating-cooling unit.

The specifications of the machine are given in Table3.

The hydraulic unit ensures adequate movement and

media pressure that can be automatically configured.

The control system is designed to control the volume of

abrasive media and the number of cycles.

One cycle in two-way AFM process is composed of

reciprocating motion of forward and backward of the

piston ram in the media cylinder.

Thus cycle time depends on the piston speed and one

cycle in the experimental study takes 2 minutes.

THE ABRASIVE MEDIA

The abrasive media that were prepared for the

present study is a mixture of polymeric carrier,

silicon carbide (SiC) abrasive particles, and 10% of

hydraulic oil.

The specifications of the abrasive media are

summarized in Table4

Before performing the experiments, the abrasive

media is run for 3–5 cycles with a trial workpiece,

so as to get uniform mixing.

Preparing the abrasive media was the hardest

process.

They have used Garnet,SiC, B4C and Al2O3 as a

raw material of abrasive media.

They were washed by them as shown in Fig. and

after that they were sieved to get optimum mesh

size of this material.

EXPERIMENTAL PROCEDURE

The experiments were performed on the Ti6Al4V.

The workpiece holder (seeFig.) was used

to hold the specimens allowing the flow

of abrasive media through the WEDMed

surfaces with an opening of 10x20 mm.

12 litres of abrasive media was flown

through in each cycle.The experiments

were carried out for 1,3,5,10,20,50 and 100

cycles.

The AFM pressure was 10 MPa and flow rate was 3 l/min.

The experiments were repeated for three specimens in each condition and the averages of the 5 surface roughness measurements were taken by using Mitutoyo SJ 401 surface measuring machine,with the cut off length 0.8 mm.

The specimens were cleaned by ethyl alcohol and weighed before and after the experiment by using SHIMADZU AUX220 balance.

RESULTS AND DISCUSSION

Measurements of surface roughness From the Fig.5 the surface roughness value decreased with increase in

number of cycles for each specimens. The surface roughness

(Ra)decreased significantly in the third cycle for Ti6Al4V specimens, the

surface roughness after 20 cycles for Ti6Al4V are decreased slightly.

Material removalThe Fig.6 shows that the material removal (MR) increases nonlinearly with the

increase in the number of cycles. And the rate of MR decreasing with number of

cycles. The reason for this slight decrease in material removal rate can be explained

as the result of asperities on the workpiece surface before AFM. When the abrasive

particles within the media machine the peaks, they become flatter than before and in

the following cycles, the material removal is decreased.In the case of the Ti6Al4V

workpiece total material removal is low.

SEM IMAGES

The EDMed surface is unlike that produced by any traditional machining process; it is characterized by globules and random debris of re-deposited and recast material. The high temperature changes the metallurgy of the material. The region affected by these thermal changes is referred to as the heat-affected zone (HAZ). The HAZ is included of a recast layer (white layer) of material that has been melted and re-solidified at the surface, white layer that is harder than the original material; contains micro cracks.

Microscopic photographs of the white layers for four groups of specimens are given inthe first cycles of the AFM process, the white layer is removed for specimens which were finished by B4C and SiC based media. From Fig.5 the improvement in the surface roughness values are similar and best improvement was occurred in specimens which were finished by B4C and SiC based media these results are well agreement to each other.

After removal of the white layer, abrasion behaviours of the four groups were changed. In the specimens (finished by B4C and SiC based media) has less smearing and ploughing. And no indentation of the abrasive particles to the surfaces was observed and the final surface roughness is better.

For Al2O3 based media finished specimen, the globules were fully removed from the surface in the fifth cycle but the lay of craters were fully removed after twentieth cycle and also have less ploughing. For specimen that were finished by Garnet based media, the globules were fully removed in the fifth cycle, but the debris was fully removed after fiftieth cycle.

SEM IMAGES OF SPECIMENS

WHITE LAYER

Fig. illustrates the removal of white layer with respect to the number of AFM cycles

for DIN 1.2379 55 HRC specimens. The results of SEM images and the sectional

microscopic views are in well agreement. The white layers were fully removed in

the first cycle of B4C and SiC based media. In the case of Al2O3 and Garnet based

media, five and twenty cycles were required to fully remove the white layers.

CONCLUSIONS

From the experimental results, the following conclusions have been derived:

The white layer formed during WEDM is successfully removed by using all types of abrasives.

The results of SEM images and the sectional microscopic views are in well agreement. The white layers were fully removed in the first cycle of B4C and SiC based media. In the case of Al2O3 and Garnet based media, five and twenty cycles were required to fully remove the white layers.

Although the trends of surface roughness measurements are similar for all media groups, the results show that the media prepared by B4C and SiC has more surface improvement than Al2O3 and Garnet.

The surface improvement nearly the same for B4C and SiC therefore, SiC can be preferred due to its lower cost and better performance.

According to the desired finishing condition the Garnet can be used for its better cost.