abrasive water jet machine
DESCRIPTION
unconventional machining process with high accuracy and precise dimension...less material removal rateTRANSCRIPT
SURESH BEERA
M.Tech Ist year
12ETMM11
Materials Engineering
SEST,UOH.
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Introduction
Machining
Conventional machining
Unconventional maching
Based on Mechanical energy (WJM,AJM,AWJM)
JET : A rapid stream of liquid or gas forced out of a small opening.
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Working principle AWJM The cutter is commonly
connected to a high pressure water pump where the water is then ejected from the nozzle, cutting through the material by spraying it with the jet of high speed water.
Additives in the form of suspended grit or other abrasives, such as garnet and aluminum oxide can assist in this process.
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AWJM - Elements
AWJM Setup
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Schematic Setup of AWJM
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Water is pumped at a sufficiently high pressure, 200-400 MPa
“Intensifier” works on the principle of pressure amplification using hydraulic
cylinders of two different cross-sections.
When water at such a pressure is passed through a suitable orifice (nozzle
having = 0.2 – 0.4 mm), the potential energy of water is converted into
kinetic energy.
This yields high velocity (~ 1000 m/s) jet of water.
Such a high velocity water jet can machine thin sheets/foils of aluminium,
leather, textile, frozen foods, etc.
commercially pure water (tap water) is used for machining.
Basic Methodology
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Injection & SuspensionHeads
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Cutting Heads
Schematic View Photographic View
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Catcher
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Typical Parameters in Entrained AWJM
Orifice – Sapphires – 0.1 to 0.3 mm
Focussing Tube – WC – 0.8 to 2.4 mm
Pressure – 2500 to 4000 bar
Abrasive – garnet and olivine - 125 to 60 micron
Abrasive flow rate - 0.1 to 1.0 kg/min
Stand off distance – 1 to 2 mm
Machine Impact Angle – 60o to 900
Traverse Speed – 100 mm/min to 5 m/min
Depth of Cut – 1 mm to 250 mm
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Material Removal in AWJM Mechanism of material removal in WJM or AWJM is rather complex.
In AWJ machining of ductile materials, material is mainly removed by low
angle impact of abrasive particles.
Further at higher angle of impact, the material removal involves plastic
failure of the material at the sight of impact.
In AWJ machining of brittle materials, material would be removed due to
crack initiation and propagation because of brittle failure of the material.
In water jet machining, the material removal rate may be assumed to be
proportional to the power of the water jet.
Advantages
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• Cut virtually any material. (pre hardened steel, mild steel, copper, brass, aluminum; brittle materials like glass, ceramic, quartz, stone)• Cut thin stuff, or thick stuff.• Make all sorts of shapes with only one tool.• No heat generated.• Leaves a smooth finish, thus reducing secondary operations.• Modern systems are now very easy to learn and safe.•Unlike machining or grinding, waterjet cutting does not produce any dust or particles that are harmful if inhaled.• Waterjet cutting can be easily used to produce prototype parts very efficiently
This part is shaped with waterjet using one tool. Slots, radii, holes, and profile in one 2 minute setup.
Disadvantages
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• One of the main disadvantages of abrasive waterjet cutting is that a limited number of materials can be cut economically. While it is possible to cut tool steels, and other hard materials, the cutting rate has to be greatly reduced, and the time to cut a part can be very long. Because of this, waterjet cutting can be very costly.• Another disadvantage is that very thick parts can not be cut with waterjet cutting and still hold dimensional accuracy. If the part is too thick, the jet may dissipate.
Waterjet lag
AWJM vs. other Modern process
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After laser cutting After waterjet cutting Abrasive Water jets are much faster than EDM.
After plasma cutting After waterjet cutting
Practical Applications Edge finishing
Radiusing
De-burring
Polishing
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Paint removal
Cleaning
Cutting soft materials
Cutting frozen meat
Textile, Leather industry
Peening
Pocket Milling
Drilling & Turning
Nuclear Plant Dismantling
AWJM - Applications
SUMMARY
Only abrasives and water is used in AWJM
In AWJM no heat generate during machining
It has faster cutting rates, longer component life and tighter tolerances will be achievable
AWJM that embrace simplicity and have a small environmental impact
AWJM is have more advantage than other modern machining process
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References Modern Machining process P.C.Pandey ,H.S. Shan,tata
mcgraw hill publication.
Principles of AWJM Andreas W.Momber,Radovan Kavacevic
www.flowcorp.com
www.flowwaterjet.com/Abrasive-Waterjet
www.waterjets.org
www.aqua-dynamics.co.uk
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THANK YOU24-10-2014 20