Download - Waterjet Cutting Machine
-
7/30/2019 Waterjet Cutting Machine
1/36
WATERJET CUTTING MACHINE
BY : KANISHK BUGALIA
SHRIYA KANNAUJIA
-
7/30/2019 Waterjet Cutting Machine
2/36
WHAT IS WATERJET CUTTING
Water jet cutting is exactly what it says, it involves using
an extremely fine jet of water travelling at high velocity,
into which an abrasive material is mixed for cutting hard
materials such as granite and titanium. This process makesa very fine cut into the material, known as a
kerf.
-
7/30/2019 Waterjet Cutting Machine
3/36
PRINCIPLE OF WATERJET CUTTING
A high pressure pump produces water at pressures upto 4100 bar .
The high pressure water is delivered to a cutting headby a small bore stainless steel pipe.
At this point it is passed through a very small orificemade from sapphire or diamond which produces anextremely thin, high velocity jet of water.
A metered amount of abrasive particles, such as sand,is then mixed with this high velocity jet of water andfocused in another nozzle called the focusing tube.
-
7/30/2019 Waterjet Cutting Machine
4/36
The work piece to be cut rests on support gridsover a tank of water.
The water jet penetrates through the materialand moves relative to the XY coordinates of thebridge supporting the cutting head.
The excess water jet energy that exists after the
jet has cut through the material, is absorbed bythe tank of water.
The cutting water and sludge can be filtered byan optional sludge removal system.
-
7/30/2019 Waterjet Cutting Machine
5/36
-
7/30/2019 Waterjet Cutting Machine
6/36
WATERJET CUTTING MACHINE
DIAGRAM OF A WATER JET
CUTTER
1 - high-pressure water inlet2 - jewel (ruby or diamond)
3 - abrasive (garnet)
4 - mixing tube
5 - guard
6 - cutting water jet
7 - cut material
-
7/30/2019 Waterjet Cutting Machine
7/36
MAJOR PARTS
HIGH PRESSURE WATER INLET
Fixed displacement piston pump.
This type of pump as used in some entry
level machines, uses a set of high speed
pistons driven directly by an electric motor
to compress the water and generate the
pressure. This type of pump develops a
cutting pressure of 1500 2000 bar which
is adequate for an entry level machine. It
also has the advantage of being cheap to
manufacture .
-
7/30/2019 Waterjet Cutting Machine
8/36
Fixed displacement piston pump
-
7/30/2019 Waterjet Cutting Machine
9/36
INTENSIFIER PUMP
This type of pump uses hydraulic pressure
developed by an electric .Motor driving a
hydraulic pump, which in turn drives a single
piston backwards and forwards in a long slowstroke, compressing the water and
developing pressures up to 4100 bar. This is
the most common type of pump found onwater jet machines.
-
7/30/2019 Waterjet Cutting Machine
10/36
INTENSIFIER PUMP
-
7/30/2019 Waterjet Cutting Machine
11/36
CHOICE OF NOZZLE
It mainly depends on three factors
Whether you are cutting with water only i.e. softmaterials like Foam, rubber, cardboard, foodstuffs,leather or textiles, or water and abrasive i.e. hard
materials like metal alloys, glass, ceramics, stone,laminates or Granite .
Quality and speed of cut required
Volume of cutting- In the case of a fixed
displacement pump, there is only one choice ofnozzle as the volume of water delivered is constantand the pressure delivery is influenced by the orificediameter. Therefore the nozzle diameter and thefocusing tube diameter must be chosen so that the
pump delivers the required cutting pressure.
-
7/30/2019 Waterjet Cutting Machine
12/36
NOZZLE
-
7/30/2019 Waterjet Cutting Machine
13/36
MIXING CHAMBER
-
7/30/2019 Waterjet Cutting Machine
14/36
ABRASIVE
The abrasive used in water jet cutting is typically a Garnet type of80 up to 120 microns in diameter. The quality of this abrasive has a
great influence on the cutting power of the water jet. The abrasive
must have a high cutting efficiency, but cause low wear on the
focusing tube and mixing chamber, create very little dust and be
environmentally friendly.The following factors must be considered in determining a suitable
abrasive :-
The grain of the abrasive must be less than half the focusing tube
diameter. The hardness of the abrasive has a direct effect on the cutting
power of the water jet.
The dust content of the abrasive must be low or it creates sludge
in the waste water.
Quality and repeatability of the cutting results .
-
7/30/2019 Waterjet Cutting Machine
15/36
Schematic illustration of the abrasive-jet machiningprocess.
-
7/30/2019 Waterjet Cutting Machine
16/36
Advantages of Waterjet Cutting
There are no heat affected zones (HAZ)
The material does not get warped, discolored or
hardened
Ability to manufacture burr-free parts
No jagged edges or burrs
Near net shape cutting
Eliminates the need for secondary operations
Can cut through thick materials
Up to 12 in thickness
-
7/30/2019 Waterjet Cutting Machine
17/36
Cuts Complex Shapes without discoloring or melting metal
Minimal Tolerances (at 0.003")
Can Pierce Material directly without the need for a pre-
drilled starter hole
High or Low Speed surface pressure flexibility for thick or
sensitive materials No Dust or Toxic Fumes Garnet is easily disposed or re-
cycled
Single or Multiple Cutting Heads
Thick or Thin, Waterjet cutting is the most flexible process
in manufacturing
-
7/30/2019 Waterjet Cutting Machine
18/36
It does not produce any dust or particles that are
harmful if inhaled. It can be easily automated for production use
High precision - no need for costly recutting.
No need for resharpening tools
Very fast implementation from drawing board to
cut piece .
-
7/30/2019 Waterjet Cutting Machine
19/36
SPEED AND QUALITY OF
WATERJET CUTTINGAs the water pressure increases, the cutting depth achievable
increases proportionally.The quality of the cut surface also
increases, however, so does the wear and tear of the seals in the
pump. Pressure changes also result in wear and tear on the seals,
so if the material needs to be pierced at a lower pressure e.g. glassand laminates, then all the piercing operations should be carried
out prior to increasing the pressure for cutting operations.
Abrasive quantity must be optimum for the material to be cut. Ifthe abrasive flow is not high enough then the cutting power of the
water jet will not be sufficient. If the abrasive flow is too high, then
the water jet becomes sluggish and reduces the cutting power
-
7/30/2019 Waterjet Cutting Machine
20/36
The cutting depth attainable decreases withincreasing cutting speed. The quality of the
cut surface also decreases with an increase incutting speed. The pressure and abrasivequantity are set for a particular material toensure optimum piercing and cutting power.
The cutting speed i.e. the speed in m/min atwhich the cutting head is driven, is varieddepending on the thickness of material beingcut and the quality of cut required.
-
7/30/2019 Waterjet Cutting Machine
21/36
The surface cut by a water jet is that the cutting stream at the bottom lags behind the point of
entry to the material at the top, causing the characteristic curve. This effect worsens with an
increase in speed and improves with an increase in pressure or abrasive flow, up to an optimum
setting. Taper of the cut is also a problem which gets worse with speed and can be virtually
parallel at the optimum feed rate.
-
7/30/2019 Waterjet Cutting Machine
22/36
CUT QUALITY
-
7/30/2019 Waterjet Cutting Machine
23/36
CUTTING TABLE
Commonly known as the table, this is the part of themachine that is generally a large tank of water, overwhich the work piece is supported.
A gantry driven in the x and y axes (and in some casesthe z axis) moves the cutting head in relation to thework piece to cut the programmed shape
. There are generally two types of system, thecantilever, where the cutting head is supported and
driven from one side of the table and a gantry typewhere the cutting head is driven along the longestdimension by a rack and pinion guide on both sides ofthe table.
-
7/30/2019 Waterjet Cutting Machine
24/36
The most important function of any cutting
table is to guide the cutting head rapidly and
smoothly and isolate any vibration from thecutting process.
-
7/30/2019 Waterjet Cutting Machine
25/36
1D-2D-3D CUTTING
ONE DIMENSIONAL CUTTING
In production applications, slitting and continuous waterjetcutting is often used. The frame of the system is usuallyquite simple, cutting speeds are quite high .
The very important criterion in this application is the highreliability and short stand still times of waterjet cutting overlong cutting periods. In contrast to roll cutting, the materialis not moved to the side and no airborne dust is created.
Many cutting heads can be applied and controlled at the
same time. Application areas: Paper and Plastic production, Gypsum
boards, Raw drywall plates, sheet metal, Cake, Frozen pizza,etc
-
7/30/2019 Waterjet Cutting Machine
26/36
TWO DIMENSIONAL CUTTING
The most popular application is the 2D cutting
table. The cutting head is located above thecutting tank, moves in X-Y axes, according to the
outputs given by the CNC-Controller.
In many cases the Z (height) axis is controllable, in
order to adapt to non-flat surfaces.
The controller is more complex and most of the
cutting speeds lie below 15 m/min.
-
7/30/2019 Waterjet Cutting Machine
27/36
Three Dimensional Cutting:
There are two subgroups of 3D applications: Robotic
applications, where the cutting head is mounted on a robotic
arm and cutting tables, where, in addition to the 3 X, Y, and Zaxes, a rotation and swivel axis are added.
Robotic applications are able to cut automotive soft materials
such as headliners, dashboards, door panels, cutting out
shapes not accessible to presses. A cutting head with 5-Axies can perform conical cuts of flat
material sheets and cut chamfers as well as perpendicularly
situated holes in tubes.
In engineering applications, the bottom end of titanium tubesused in chemical reactors can be cut without weakening the
material.
-
7/30/2019 Waterjet Cutting Machine
28/36
3D WATERJET CUTTING
-
7/30/2019 Waterjet Cutting Machine
29/36
CHALLENGES TO WATERJET
Keeping in mind the wide spectrum of possibleapplications there are a few areas, which aresomewhat challenging for this cutting method.
The jet does not like large openings in hard
materials. When cutting a multi-layer profile at thetop of the workpiece, a slowdown in the velocity ofthe outside of the jet is observed, while at the sametime, the centere of the jet maintains the highkinetic energy.
As a result, upon exiting the first layer of thematerial, an increase in width of the jet occursresulting in inferior cutting quality and parameters .
-
7/30/2019 Waterjet Cutting Machine
30/36
When cutting piles of sheet metal, it is importantto make sure the plates are as flat as possible in
order to prevent the creation of pockets betweenthe layers .
By tube cutting, the jet on the lower side of the
tube is somewhat wider. A solution here can be arotating system facilitating the rotation of thetube in the process of cutting.
Keeping these considerations in mind, waterjet is
very well suited to cut multi-layer materials.
-
7/30/2019 Waterjet Cutting Machine
31/36
-
7/30/2019 Waterjet Cutting Machine
32/36
Application & flexibility
-
7/30/2019 Waterjet Cutting Machine
33/36
-
7/30/2019 Waterjet Cutting Machine
34/36
WATER TREATMENT NECESSARY
Inlet water should be treated for either the removal of hardness or thereduction in Total Disolved Solids (TDS). A water treatmentproducing TDS content of less than 0.5 ppm is not recommendedsince the aggressiveness of the purified water may damage theintensifier pump components. Treated water must have a pH valueof 6 to 8.
If your water has low TDS (200 ppm), water quality is considered
poor and should be treated with DI or RO equipment. If your water has high silica concentration (>15 ppm), dual strong-
base DI is recommended.
-
7/30/2019 Waterjet Cutting Machine
35/36
WATERJET ABRASIVE RECYCLING
SYSTEM
The system is designed to remove sludge from anabrasive water jet cutting tank or integrate into anexisting abrasive removal system. The recycled abrasivecan be placed in the hopper for use again with theoptional abrasive transport system. The abrasive isremoved from the tank using patented nozzles thathave no moving parts. The nozzles work best whenburied under approximately 12" (30 cm) of sludge. Thesludge is sent to the top of a series of vibrating screens
where usable abrasive larger than 100 mesh isseparated. This is then dried and made ready to useagain
-
7/30/2019 Waterjet Cutting Machine
36/36
Waterjet-A technology on rise
A very quickly guided waterjet, which just manages to cut throughthe material, has a V-shaped profile, creating a uneven surface atthe bottom. Should the jet be guided in a slower fashion, theprofile will be more even. As a general rule at one fifth of themaximum cutting speed, a perfectly perpendicular with a near
perfectly polished surface is achieved. A further slowing of themovement speed, leads to a loss of guidance in the material,erosion in the lower sections of the work piece, and a creation ofan A-shaped profile.
Plastic coated iron, plastic foil covered aluminum, styrofoam
covered gypsum board ... Waterjet technology was used for theremoval of the Russian Kursk nuclear submarine from thebottom of the sea. The steel body was covered with a thick layer ofrubber. And this gets us to yet another advantage of this methodit is not affected by moisture, working also under water.