ice jet machining

SeminarON

ICE JET MACHINING

GUIDED BYPROF. N. D. GHETIYA

Prepared byVirendra11BME050

OUTLINE

Introduction

Generation of the Ice and apparatus

Hardness Of Ice particle

Comparison of AWJ, WJ & IJM

Machining is a broad term to describe removal of material from a workpiece.

Introduction

Machining

Traditional machining processes Non-Traditional machining processes

•Otherwise the process is non traditional

Presence of tool harder then

workpiece

Relative motion

between Tool and

work

Traditional

machining

•IJM is a non-traditional machining process

Why Non-traitional machining process

• If

Traditional machining processes are UNSATISFACTORY OR UNECONOMICAL

Work piece MATERIAL is too HARD, STRONG, OR TOUGH

Work piece is TOO FLEXIBLE TO RESIST CUTTING FORCES or TOO DIFFICULT TO CLAMP.

TEMPERATURE RISE or residual stresses are undesirable or UNACCEPTABLE.

Part SHAPE is very COMPLEX with internal or external profiles or small holes.

What is ice jet machining?

• In Abrasive water Jet Machining process(AWJM) abrasive particles like silicon carbide and aluminum oxide are used for machining.

• Ice jet machining is Derivative of AWJM machining process in which ice particles are used in place of abrasive particles.

• The ice particles can be prepared beforehand using an ice particle generator, stored in a reservoir and then fed to the conventional entrainment based jetting head.

AWJ and IJ

• In AWJ, waste of water is very high as waterjet contains abrasive particles. To reuse the water very complicated water cleaning system has to be employed.

• While in IJ, ice is used instead of Abrasives. So as ice melts into the water, water treatment gets eliminated and we can reuse the water.

• Also solid waste is produced in the AWJ technology and it pollutes the environment.

• While compared to AWJ, IJ technology is environmental friendly.

Use of the technology

Other Processes done with use of ice

Dry ICE DEBURRING PROCESS Removal of burrs from edges and holes. Where burrs could not be removed with any other

means like filing or grinding.DeburrigDry ICE BLASTING PROCESSES Used for cleaning purpose Cleaning of engine block can be done with ice

blasting process effectivelyBlasting process

Generation of ice

There are 2 approaches:

1 •Generating the ice in a generator before mixing it to the water jet.

2•Forming ice particles during water jet formation by introducing a cooling gas like liquid nitrogen.

Generation of ice

Using Ice Generator Figure shows ice generation

by introducing the liquid nitrogen to the atomized water droplets.

Temperature of the liquid nitrogen is -196°C.

As the water comes into contact with liquid nitrogen it is converted into ice particles.

It is collected into the storage tank and additionally cooled.

By introducing cryogenic gas to water jet

• Liquid Nitrogen is directly introduced to the jet of the ice.

• Due to low temperature of the LN, ice particles are formed into the jet of ice.

Apparatus

• Apparatus for the IJM are different depending upon the procedure by which the ice particles are generated.

• But,basically components like nozzle, compressor, atomizer etc remains same.

Apparatus using ice particle generator

• The compressor used for the purpose can produce maximum pressure of 340 Mpa.

• The ultrasonic atomizer used in the ice particle generator can produce uniform water droplets of 45 to 90 microns and 2 ltr/hr to 12 ltr/hr.

• The diameter of the nozzle is 0.175mm and diameter of focusing tube is 0.75mm.

• Standoff distance is kept 3mm to 5mm.

Ice formed at 8° C and 60 micrometer. Mean dia. Of the ice was found to be 91.8microns

IceJet machning apparatus developed under Project ICEJETTECNALIA, UL, IAMCUT

Basic characteristics

• WATER PRESSURE:50 to 700 Mpafor harder materials: 700 Mpafor softer materials: 50 Mpa

• Water nozzel diameter:0.1mm to 0.3mm• Speed of water jet:500 to 900 m/s• No heat affected zones.• Treatment of all kind of materials.

• All the ice found on earth, Crystal Structure of Ice is Hexagonal Closed Pack (HCP)

• For study of the hardness of ice, we have to know about the Crystal axis(c-axis) ice crystal.

• The hardness of the ice is not isotropic. After experiments it is found that hardness changes with the orientation of c-axis.

Hardness of Ice Crystal

Crystal axis of the Ice

Brinell Hardness Test

• An Olsen Baby Brinell Hardness Tester was used.

• The machine comes equipped with a 1/16 inch ball to be used with a load of 12.61 kg.

• Preliminary tests with ice samples showed that this load caused excessive cracking

SO,Modifications had to be done.

Modifications in the equipment

1. The 12.61 kg. Load was replaced by a platform on which different weights could be placed, and

2. The 1/16 inch ball was replaced by a hardened 1/8-inch ball. The weight of the ball stem plus platform was 570 g. which was added to the weights placed on the platform to give the total load applied.

Specimen of Ice

• Approximately 7×4×1 cm cubes were used, oriented so that the c-axis Lay parallel to the large face of one plate and normal to the large face of the other.

• Polished to a mirror finish, and freeze onto glass sheet to provide hard base.

Calculation of BHN

• Brinell hardness numbers were computed from the standard Brinell formula:

• Where,• H is the Brinell hardness number• K is the applied load in kilograms• D is the diameter of steel ball in mm.• d is the diameter of the impression in mm.

Modified equation

• As standard equipment was not used, the equation also had to be modified.

Wherek is the hardness numberǝ is the width of the cut in microns

Measuring the results

• The specimen was coated with liquid polystyrene.

• Because the indentations were made at low temperature, and measurements were made at higher temp. so considerable fogging was there.

• So for accurate results, indentation made on the ice was measured on the polystyrene sheet.

Results

• By the experiment a graph was plotted of BHN vs Temprature and it was found that the hardness of ice increases with decrease in temperature.

• After doing the experiment it was found that the hardness of the ice particle was higher parallel to the c axis and less perpendicular to the c axis of the ice particle.

• BHN of ice was found to be ranging between 4 to 17.

Comparison of AWJ, WJ and IJM

Comparative study of material Drilling by WJ and IJ

Cost analysis for AWJ, WJ and IJM

Cost in Rupees/hour

Conclusion

• By doing the technical analysis of the IceJet technology it can be concluded that production and injection of ice particles in to the water jet it is not a complicated task but it requires continuous monitoring of the process to control the temperatures in order to avoid clogging and melting of the ice particles. However this can be automated.

Conclusion

• By doing the economic analysis, it can be seen that costs are very similar for AWJ and IJ.

• Most significant expense is the cost of abrasive particles.

• The costs of AWJ will reach the costs of IceJet in the near future as abrasives are minerals & are limited in source.

• Ice Jet is an environmentally friendly process which makes worth its value.

Questions?

Thank You