3/6/2074

Water-JetMachining

Commercial CNC water jetmachining system and

cutting heads

3161201"4

Application WJM & AWJM

Application. Paint removal. Cleaning. Cutting soft materials. Cutting frozen meat. Textile, Leather industry. Mass lmmunization. Surgery. Peening. Cutting. Pocket Milling. Drilling. Turning. Nuclear Plant Dismantling

Materials. Steels. Non-ferrous alloys. Ti alloys, Ni- alioys. Polymers. Honeycombs" Metal Matrix Composite. Ceramic Matrix Composite. Concrete. Stone

- Granite

. Wood

. Reinforced plastics

. Metal Polymer Laminates

. Glass Fibre Metal Laminates

Examples of various parts produced wate r-jet cutting process.

31612014

,e!I lt f- r';ot:,u:\i!igl--..,*"

Water-JetCutting Process

(bi (r)(a) Schematic illustration of the water-jet machining process. (b) A computer-controlled water-jet cutting machine cutting a granite ptate. (c) Examples of various

Schematic set-upof AWJM

1. LP Boosler2. Hydraulic drive3. Additive mixer4- Direction conrrol5. lnten6ifier5A-LP lntensifier58.HP lntsilsifisr6. Accumulator

lntensifier -

Schematic

iiI',i*

3/6/}a14

APPLICATIONThe applications and materials, which are generally

machined using WJ and AWJ, are given below:Applicatione Paint renroval. Cleaning. Cutting soft materials. Cutting f rozen meat"

Textile, Leather industry. Mass lmrnunization. Surgery, Peeningr Cutting"

Pocket Milling. Drilling. Turning. Nuclear Plant Dismantling

Materialso Steels. Non-ferrous alloys"

Ti alloys, Ni- alloys. Polymers'Honeycombs. Metal Matrix Composite. Ceramic Matrix Compositee Concreteo Stone

- Granite

. Wood

. Reinforced plasticso Metal Polymer Laminates. Glass Fibre Metal Laminates

Tra.iectory of anabrasive pariicle

lnieraciian wtthfociissinc iui-re

Mixing chamber

Schemotic view ofmixing pracess

Focusslng tube

Schemqtic andphotographic view afthe cutting head

,, FtUh,piessur' r,ai*r

..

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< -

+Ji t5i; ii

WaterJet

3/6/2014

The velocity of the water jet thus formed can be estimatedassuming no losses as

v*i= (Zp* I p)r/,Mixing process may be mathematically moo",,uo as follovrs. Taking into aecount theenergy loss during water jet formation at the orifice, the vrater jet .relocity nray begiven as,

.. _ rr/ I I 7t ,, r! = Velocity coefficientof the orificer -

T i--------',7 '1l .r1 +=Coefficientof"vena-contractct,'! f i' cd= Dischotge rcefficient of ihe orifice

4,, : t! X 1',.r :{ ,l,r1ricI] , :

'Ihe volume flow rate o{ water !" - ('i r " -, "may be expressed as:

. II l, ,,,4,, - d "' rl,- :< t[' \l ,],t'' Il . li,,(l ,, = ( , i. '. t/ ,- '

.t i...{. "-1 1* /r,,

The total power of the water jet P,til'tt,

x(ltt

Y. {:i Y

fIt ""'

t;t1 n.ti-Ati

=11

:11

- i.Momentum of the jet before and

after mixing is conserved.

i.,.1] "'r- t'1.., t

P

.l.)t) 1

1 -.'--

----1.irri

I' r,ii- rt ,

l? = i*ading {actor =

11 = momentum loss factor.

^ i'j ',t -

l-l'll'u x i-_" ! lri,i- - --;-t-t'11

v;,.

fI;-+

7 I

tIj...

'jrr.i, t_:.. lt )r I'i?ii:'l

316/2A14

Eypaes Principle

B'vpass trressure vfsse

kli8a IY*$rY

Scbematic af /1WJt\4(Suspension type)

l:tE-t:f\

!ai ir3laihr pidtrjs i i!B

*.: nerl.rabr

ftf,:-/

././,

,"'q--L I GiIB JF

-i_

i

:'

llCatcher

- ------'-lr

!ii, i

' i)

: !,'i,,,

i

io i'iN il.;z t..l

Waterjet lag

lndilect Pumpin5lhpr,. ale[

6

3/6/201,4

ir. I ,r*ta,,,acr.,i Mechanism of. zl.e

,r.*=-. material removali\,i t'\ ,' i: \ , I schenotic of A'r\:Jrvt kerfIt1 \r\t Jjii(

Ir

Striation Photogrophic view oJ kerfmarks (longitudinalsection)

Mechanism of rnaterial removalThe general domain of parameters in entrained typeAWJ machining system is given below:. Orifice

- Sapphires

- 0.1to 0.3 mrn

n Focussing Tube -

WC -

0.8 to 2.4 mm. Pressure

- 2500 to 4000 bar

. Ahrasive -

garnet and olivine - #125 to #60. Abrasive flow - 0.1to 1.0 Kglmin. Stand off distance

- 1 to 2 mm

. Machine lmpact Angle -

60o to 900. Traverse Speed

- 100 mm/min to 5 m/min

. Depth of Cut -

1 mm to 250 mm

3/612014

In water jet machining, the material removal rate may be assumed to beproportional to the power of the water jet. The proportionality constant L isthe speciffc energy requirement and would be a property of the yvork material.

ii 'r,- '!

I i' ilI /r

power of the abrasive phase of the abrasive urater jet can be estimated as,

Thus it may be assumed that the material removat rate is proportionalto the power of abrasive phase of AWJ. The water phase does notcontribute to material removal in AWJM.

-j

s:ht

it:: ;''.,, '; t' ,, - , ,i .

-

,i

.1rnRD

MRR wvr

u 1ot= speCiqc energy requirement in machining a material irrAWJM

4= depth of penetrationw = width of the kerf = (w ,oo * w ,*,,,,,,,) / 2

x d, , the diameter oF the focussing tube or nozzle or the insertr,,= traverse speed of the AWJ or cutting speed

Therefore, r+ MRR: hrd,v, Q ir,=i fi nt tt+ ' "l r-R j ll-' :tr..,il'-r',. ! rr,,l*Tll

,,t^,

-!i . f

-1 ''f1 t

i--f.i

ni'.,

rs tn? ioaCinil ilarar.ielet

{ = koefisien, yang memperhitungkan beber-apa faktor seperti ketajaman atau kusamdari kerapuhan. aLrrasi[ stand-off distance, process inhr:niogenities etc

Opiimal loading r"atio is required to be deterrrinecl by r.differentiating with respect to the loading ratro, R

r:-

=f,..-..'--".-"_.------._;! rri_tl

- ti I

h^_iI-N,.4

,t l;'=L,l-iir

--,t-,l* Fr- iir

i -,R : t-t ='

:Ll

3l6l2aM

t],25

lLZ

$.I5

0.1

0.0s

0 0.5 t,0 1"5 2.9 2.5 $.0Voriotian in cutting obility of AWJM with mixing rotio

Problerns

1. Assuming no losses, determine water jet velocity, whenthe water pressure is 4000 bat being issued from anorifice of diameter 0.3 mm

2. Determine the mass flow rate of water for the givenproblem assuming all related coefficients to be 1

3. If the mass flow rate of abrasive is 1 kg/min, determinethe abrasive water jet velocity assuming no loss durinqmixing process using the above data (data of Question.1, 2 and 3)

4. Determine depth of penetration, if a steel plate is AWJmachined at a traverse speed of 300 mm/min with aninsert diameter of 1 mm. The specific energy of steel is13.6 J/mm3

"\-\-l*t\ \. \

----\-- \-,\

:i

-

* * -t* -- - *

I

';ti

* * -: - - - -t- - - -

!!1lil

.---j i_***

ririiiri

tlrtlrt/iltI

-l:*-11 IIr rttIii

*.4--*Ir

it!!i;

- -! - * * -,- - - -!irittl!

-J---*l--.--Itl!II,tlt

I

a

I

iit

t

i

iet

;iI

Tt

tI

I

ItI

t

i!

316/2014

o,26

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fi.2

s.1s

0"I

0.05

0 0.5 t.0 i"5 2.9 2.5 $.sVariation in cutting obility of AWJM with mixing ratio

Problems

1. Assuming no losses, determine water jet velocify, whenthe water pressure is 4000 bar, being issued from anorifice of diameter 0.3 mm

2. Determine the mass flow rate of water for the givenproblem assuming all related coefficients to be 1

3. If the mass flow rate of abrasive is 1 kg/min, determinethe abrasive water jet velocity assuming no loss durinqmixing process using the above data (data of Question.1, 2 and 3)

4. Determine depth of penetration, if a steel plate is AWJmachined at a traverse speed of 300 mm/min with aninsert diameter of 1 mm. The specific energy of steel is13.6 J/mm3

{

I

I

iI

I

I

;rllltlillll,i

{+.-*-i*-'.--+*,-{'ttitiall

L

rli-l * * - *,- - i- -:r1Ili)titlltl

J----r----L,!illttt,ttt,ltll