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Abrasive Jet Machining – Components, Working Precept, Software


On this article you’ll find out about Abrasive Jet Machining, together with the working precept, components, working, purposes, benefits and disadvantages.

Abrasive Jet Machining

Abrasive Jet Machining is a non conventional technique of eradicating supplies by utilizing a centered stream of abrasive grains of Al2O3 or SiC carried by high-pressure gasoline or air at a excessive velocity is made to impinge on the work floor by means of a nozzle of 0.3- to 0.5-mm diameter.

In different phrases, Abrasive jet machining is the method of impinging a high-speed stream of abrasive particles onto a piece floor through a nozzle with high-pressure gasoline or air, and metallic elimination happens attributable to erosion attributable to high-speed abrasive particles.

The influence of the particles generates a concentrated pressure ample to carry out operations corresponding to slicing; the fabric is eliminated by the erosion of labor materials with abrasive grits at a velocity of 150-300m/s. Abrasive grits are utilized in a high-velocity gasoline stream.

Working Precept of Abrasive Jet Machining

The working precept of abrasive jet machining is the use of a high-speed stream of abrasive particles carried by a high-pressure gasoline or air on the work floor through a nozzle.

The metallic is eliminated attributable to erosion attributable to abrasive particles impacting the work floor at excessive speeds. With every influence, small bits of fabric are loosened, exposing a brand new floor to the jet.

This course of is principally employed for such machining works that are in any other case troublesome, corresponding to skinny sections of arduous metals and alloys, slicing of fabric which is delicate of warmth harm, producing intricate holes, deburring, etching, sprucing and so forth.

Abrasive Jet Machining Components

1. Gasoline Provide

Within the machining system, a gasoline (nitrogen, CO2, or air) is provided below a strain of 2 to eight kg/cm2 . Oxygen ought to by no means be used as a result of it causes a violent chemical response with workpiece chips or abrasives. This abrasive and gasoline combination is ejected at a excessive velocity of 150 to 300 m/min from a small nozzle mounted on a fixture.

2. Filter

The filter cleans the gas provide in order that dust and different impurities don’t impede the method’s progress.

3. Strain Gauge

The strain gauge is used to regulate the compressed air strain utilized in abrasive jet machining. because the strain determines the depth of lower and the quantity of pressure required to chop

4. Mixing Chamber

Abrasive powder is fed into the blending chamber, and the quantity of abrasives might be managed utilizing a vibrator. In order that the abrasives and gases are completely blended within the mixing chamber.

5. Nozzle

The nozzle is used to improve the speed of the superb abrasive jet slurry on the expense of strain, as a result of we all know that reducing the strain causes the speed to extend. The jet’s velocity will likely be between 100 and 300 meters per second.

The nozzle might be adjusted to realize the specified angular slicing and the fabric might be eliminated by influence erosion.

Due to the excessive put on, the nozzle is normally product of tungsten carbide. The nozzle’s diameter is roughly 0.2-0.8mm.

The nozzle’s materials must be corrosion resistant. The nozzle has a round or rectangular cross-section, and the pinnacle might be straight or at a proper angle.

6. Abrasives

In abrasive jet machining, silicon carbide and aluminum oxide glass beads are used as abrasives. The abrasives’ shapes might be common or irregular. The abrasives vary in measurement from 10 to 50 microns. The mass movement fee of the abrasives is between 2 and 20 grams per minute.

The selection of abrasives is decided by the MRR, the sort of labor materials, and the stage of machining accuracy required.

Aluminum oxide (Al2O3) measurement 12, 20, 50 microns is sweet for cleansing, slicing, and deburring; Dolomite measurement 200 mesh is used for Etching and sprucing.

Sodium bicarbonate has a particle measurement of 27 microns and is used for cleansing, deburring, and slicing tender supplies.

7. Workpiece

The metallic elimination fee is decided by the nozzle diameter, the composition of the abrasive gasoline combination, the hardness of the abrasive particles and the hardness of the work materials, particle measurement, jet velocity, and the space of the workpiece from the jet. In slicing glass, a typical materials elimination fee for abrasive jet machining is 16 mm/min.

8. Regulator

The regulator is used for controlling the movement of compressed air flowing by means of the pipe.

Working of Abrasive Jet Machining

Within the machining system proven in Fig, a gasoline (nitrogen, CO2, or air)
is provided below a strain of 2 to eight kg/cm2 . Oxygen ought to by no means be used
as a result of it causes a violent chemical response with workpiece chips or
abrasives. After filtration and regulation, the gasoline is handed by means of a mixing chamber that accommodates abrasive particles and vibrates at 50 Hz.

working principle of Abrasive Jet Machining

From the blending chamber, the gasoline, together with the entrained abrasive particles (10–40 µm), passes by means of a 0.45 mm diameter tungsten carbide nozzle at a velocity of 150 to 300 m/s. Aluminum oxide (Al2O3) and silicon
carbide powders are used for heavy cleansing, slicing, and deburring.

Magnesium carbonate is really helpful to be used in mild cleansing and etching, whereas sodium bicarbonate is used for superb cleansing and the cut- ting of sentimental supplies. Business-grade powders should not appropriate as a result of their sizes should not nicely categorized. They might include silica mud, which generally is a well being hazard.

It’s not sensible to reuse the abrasive powder as a result of contaminations and worn grit will trigger a decline of the machining fee. The abrasive powder feed fee is managed by the amplitude of vibrations within the mixing chamber. The nozzle standoff distance is 0.81 mm. The relative movement between the workpiece and the nozzle is manually or routinely managed utilizing cam drives, pantographs, tracer mechanisms, or utilizing pc management in response to the lower geometry required.

Masks of copper, glass, or rubber could also be used to focus the jet stream of abrasive particles to a confined location on the workpiece. Intricate and exact shapes might be produced by utilizing masks with corresponding contours. Mud elimination gear is included
to guard the surroundings.

Purposes of Abrasive Jet Machining

Lets talk about what’s use of abrasive jet machining :

1. Drilling holes, slicing slots, cleansing arduous surfaces, deburring, and sprucing

2. Deburring of cross holes, slots, and threads in small precision components that require a burr-free end, corresponding to hydraulic valves, plane gas techniques, and medical home equipment.

3. Machining intricate shapes or holes in delicate, brittle, skinny, or difficult-to-machine supplies

4. Insulation stripping and wire cleansing with out affecting the conductor

5. Micro-deburring of hypodermic needles

6. Frosting glass and trimming of circuit boards, hybrid circuit resistors,
capacitors, silicon, and gallium.

7. Removing of movies and delicate cleansing of irregular surfaces as a result of
the abrasive stream is ready to comply with contours

8. It’s used for abrading and frosting glass, ceramics, and refractories and is inexpensive than etching or grinding.

9. Cleansing of metallic layering, corresponding to resistive coating.

10. Small casting deflashing and parting line trimming on injection molded components and forgings

11. It’s used to engrave registration numbers on toughened glass utilized in car home windows.

12. Used to scrub metallic molds and cavities.

13. Cleansing surfaces of corrosion, paints, glues, and different contaminants.

Benefits and Disadvantages of Abrasive Jet Machining

Benefits

  • As a result of AJM is a cool machining course of, it’s best fitted to machining brittle and heat-sensitive supplies like glass, quartz, sapphire, and ceramics.
  • The method is used for machining tremendous alloys and refractory supplies.
  • It’s not reactive with any workpiece materials.
  • No software adjustments are required.
  • Intricate components of sharp corners might be machined.
  • The machined supplies don’t expertise hardening.
  • No preliminary gap is required for beginning the operation as required by
    wire EDM.
  • Materials utilization is excessive.
  • It may possibly machine skinny supplies.
  • A excessive floor end might be obtained by means of this course of.

Disadvantages

1. The elimination fee is gradual.

2. Stray slicing can’t be prevented (low accuracy of ±0.1 mm).

3. The tapering impact could happen particularly when drilling in metals.

4. The abrasive could get impeded within the work floor.

5. Appropriate dust-collecting techniques must be offered.

6. Gentle supplies can’t be machined by the method.

7. Silica mud could also be a well being hazard.

8. Atypical store air must be filtered to take away moisture and oil.

9. Course of capability is much less attributable to a low materials elimination fee.

10. Whereas machining tender supplies, abrasive turns into embedded, lowering the floor end.

11. The tapering of the opening attributable to the unavoidable variation of an abrasive jet disturbs slicing accuracy.

12. Due to stray slicing, accuracy is poor.

13. As a result of a mud assortment system is a fundamental requirement for stopping atmospheric air pollution and well being hazards, the extra value will likely be current.

14. The nozzle’s life is restricted (300 hours).

15. As a result of the sharp edges of abrasive powders put on down and smaller particles can clog the nozzle, they can’t be reused.

16. A brief standoff distance could cause nozzle harm.

17. Due to the flaring impact of the abrasive jet, the method accuracy is poor.

18. A taper will likely be current in deep holes.

19. AJM The method is dangerous to the surroundings and causes air pollution.

20. Abrasive particles within the air can create a hazardous surroundings.

Impact of Grain Measurement And Stream Charge of Abrasives on Materials Removing Charge

At a given strain, MRR will increase with rising abrasive movement fee and is decided by abrasive particle measurement.

Nonetheless, after reaching the optimum worth, MRR decreases because the abrasive movement fee is elevated additional.

It is because the mass movement fee of the gasoline decreases because the abrasive movement fee will increase, and thus the blending ratio will increase, leading to a lower in materials elimination fee attributable to a lower in out there power for erosion.

Impact of Exit Gasoline Velocity And Abrasive Particle Density:

The velocity of the service gasoline that transports the abrasive particles varies considerably with the density of the abrasive particles.

When the inner gasoline strain is close to twice the strain on the exit of the nozzle and the abrasive particle density is zero, the exit velocity of gasoline might be elevated to important velocity.

Exit velocity will lower for a similar strain situation if the density of abrasive particles is step by step elevated.

It’s as a result of the kinetic power of the gasoline is used to maneuver the abrasive particles.

Impact of Mixing Ratio on Materials Removing Charge:

Because the abrasive’s mass movement fee will increase, its velocity decreases, lowering the out there power for erosion and, in the end, the fabric elimination fee.

Results of Nozzle Strain on MRR

The abrasive movement fee might be elevated by rising the service gasoline movement fee. As the inner gasoline strain rises, so does the abrasive mass movement fee, and thus the MRR.

The fee of fabric elimination will increase because the gasoline strain rises. The kinetic power of the abrasive particles is answerable for materials elimination in the course of the erosion course of.

Why are abrasive particles not reused in Abrasive jet machining?

Superb abrasive particles entrained in a gasoline stream are permitted to influence the work floor at excessive velocity (100–300m/s) to step by step degrade materials within the abrasive jet machining (AJM) course of. Impression erosion is the mechanism for materials elimination. The service gasoline transports eroded materials within the type of stable small particles and utilized abrasive grits away from the machining zone. Due to the next two causes, reusing these abrasive particles just isn’t recommended.

  1. Put on particles contaminates abrasives (eliminated work materials).
  2. Abrasives lose their sharp edges, lowering their slicing effectiveness.

Ceaselessly Requested Questions

What’s use of abrasive jet machining?

Frequent purposes embody slicing heat-sensitive, brittle, skinny, or arduous supplies. It’s particularly used to chop intricate shapes or kind particular edge shapes.

Which gasoline is utilized in abrasive jet machining?

Abrasive jet machining creates a jet by mixing gasoline with abrasive particles. The gasoline used is called service gasoline. Air, carbon dioxide, and nitrogen are three of essentially the most generally used service gases. Oxygen isn’t used as a service gasoline as a result of it could actually oxidize the work piece’s floor.

AJM can be utilized for

Abrasive jet Machining course of can be utilized for can be utilized for deburring, slicing, cleansing and for a lot of different heavy obligation purposes.

In abrasive jet machining course of the abrasive particles must be

In AJM, usually, the abrasive particles of round 50 μm grit measurement would impinge on the work materials at a velocity of 200 m/s from a nozzle of I.D. of 0.5 mm with a stand-off distance of round 2 mm.

How is the fabric eliminated in Abrasive jet machining?

In abrasive jet machining, a centered stream of abrasive particles is impinged on the work floor by means of a nozzle and work materials is eliminated by erosion by excessive velocity abrasive particles carried by excessive strain air or gasoline. As a result of the service gasoline acts as a coolant, the slicing course of is cool. The high-velocity abrasive stream is created by transferring the strain power of the service gasoline or air to its kinetic power, leading to a high-velocity jet.

Abrasive Jet Machining MCQ

Q. In Abrasive jet machining, work piece materials of eliminated by which of the next means?
a) Vaporization
b) Electro plating
c) Mechanical abrasion
d) Corrosion
Reply: c

Rationalization: Abrasive particles hit the floor with excessive strain and excessive velocities, which removes the fabric.

Q. Metallic elimination fee in Abrasive jet machining will increase with

a) Enhance in standoff distance however decreases past a sure restrict
b) Lower in abrasive movement fee
c) Lower in grain measurement in grain measurement of abrasives
d) Not one of the talked about
Reply: a
Rationalization: MRR is instantly proportional to standoff distance as much as sure restrict. After sure restrict, kinetic power of abrasives begins lowering.

Q. Which kind of supplies might be machined utilizing Abrasive jet machining?
a) Glass
b) Ceramics
c) Arduous supplies
d) All the talked about

Reply: d
Rationalization: Supplies like ceramics, glass, arduous and tremendous arduous supplies might be machined utilizing Abrasive jet machining.

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