WATER JET CUTTING

Presented By:

V.LOGANATHAN M-TECH (PDM)

INTRODUCTION TO WATER JET

Key element in WJM is a jet of water.

Water jet travels at velocities as high as 900 m/s.

When the jet of water strikes a work piece surface, the erosive force of water removes the

material rapidly.

The water, in this case, acts like a saw and cuts a narrow groove in the work piece material.

True cold cutting process – no HAZ (Heat Affected Zones), mechanical stresses or operator

and environmental hazards

PRINCIPLE

When the a high pressure (150-1000 MPa) and high velocity (540-1400 m/s) of water jet

comes out of nozzle and strikes the work piece of the material, its kinetic energy is converted

into pressure energy including high stresses in the work material. When this induced stress

exceeds the ultimate shear stress of the material, small chips of the work piece material get

loosened and fresh surface is exposed.

The fluid flow rate is typically from 0.5 to 2.5 l/min

Water is the most common fluid used, but additives such as alcohols, oil products and

glycerol are added when they can be dissolved in water to improve the fluid characteristics.

WHY USE WATER JET?

It can cut almost everything, with greater efficiency and productivity.

It is one of the fastest growing major machine tool processes in the

world due to its versatility and ease of operation.

Water jets cut accurately, reduced scrap-saving money through

greater material utilization.

HOW WATER JET WORKS?

High pressure (60,000 psi), which when bombarded on

the work piece erodes the material.

A high velocity water jet when directed at a target in such

a way that, its velocity in virtually reduced to zero on

striking the surface. Because of this water jet will make a

hole in the material if the pressure is high enough.

SCHEMATIC LAYOUT OF WJM

TYPES OF WATER JET

PURE WATER JET

Pure Water jet is the original water cutting method. In

which pure water is compressed at very high pressure &

released through a narrow opening.

ABRASIVE WATER JET

Abrasive water jet is same as pure water jet and within

just 2 minutes the very same water jet can be transformed into

an abrasive water jet to cut hard materials by adding abrasives

to it.

PURE WATER JET CUTTING

1. Water under pressure

2. Water nozzle

3. Pure water jet

4. Work piece

5. Cut width

PURE WATER JET CUTTING

Pure Water jet is the original water cutting method. In which pure

water is compressed at very high pressure & released through a

narrow opening.

It forms water jet, which comes out at the speed of up to 850 m/s

The largest uses for pure water jet cutting are disposable diapers,

tissue paper, and automotive interiors .

Provides Very thin stream (0.004 to 0.010 inch in diameter is the

common range) .

Very little material loss due to precise cutting.

PURE WATER JET CUTTING

Non-heat cutting ,Usually cuts very quickly.

Able to cut soft, light materials(e.g., fiber glass

insulation up to 24" thick).

Used to cut soft, thin, or porous material

Silicone

VCT (tile)

Foam

Cork

Teflon

Composites

Plastic

ABRASIVE WATER JETS

1. Water under pressure

2. Water nozzle

3. Water jet

4. Abrasive feed (unpressurised)

5. Mixing chamber (vacuum chamber)

6. Abrasive nozzle (focusing tube)

7. Water jet with abrasive

8. Cut width

ABRASIVE WATER JETS

In abrasive water jet, the water jet stream accelerates abrasive particles and

those particles erode the material from the work piece.

The abrasive Water jet is hundreds of times more powerful than the pure

Water jet.

Extremely versatile process, No Heat Affected Zones, No mechanical

stresses.

Easy to program

Thin stream (0.020 to 0.050 inch in diameter)

10 inch thick cutting, Little material loss due to cutting

Quickly switch from pure water jet to abrasive water jet.

TYPES OF ABRASIVE MATERIALS

garnet , aluminum oxide , olivine , silica sand , silicon carbide , etc .

Virtually any material can be cut by using abrasive jet

machining method , i.e. harder materials like titanium to steel.

Abrasive particles must be hard ,high toughness, irregular in

shape & edges should be sharp (usually about 0.001 in)

PARAMETERS AFFECTING THE

PERFORMANCE OF WJM

CUTTING RATES FOR DIFFERENT

MATERIAL THICKNESSES

ADVANTAGES OF WATER JET

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

ADVANTAGES (CONTINUED)……

Cheaper than other processes.

Cut any material. (mild steel, copper, brass, aluminum; brittle

materials like glass, ceramic, quartz, stone)

Make all sorts of shapes with only one tool.

Unlike machining or grinding, water jet cutting does not produce any

dust or particles that are harmful if inhaled.

DISADVANTAGES

Abrasive powder cannot be reused.

Very thick parts can not be cut with Water Jet

One of the main disadvantages of water jet cutting is that a

limited number of materials can be cut economically.

Taper is also a problem with WJM in very thick materials.

WJM is very expensive process. It is not suitable for mass

production because of high maintenance requirements.

PROCESS COMPARISON

WATER JETS VS. LASERS CUTTING

Abrasive water jets can machine many materials that

lasers cannot. (Reflective materials in particular,

such as Aluminum and Copper)

Uniformity of material is not very important to a

water jet.

Water jets do not heat your part. Thus there is no

thermal distortion or hardening of the material.

Water jets are safer.

Maintenance on the abrasive jet nozzle is simpler

than that of a laser.

PROCESS COMPARISON

FLAME CUTTING VS. WATER JET

CUTTING

If the cutting edge quality of flame cutting fulfills the

requirements, then flame cutting is more cost-effective

than water jet cutting.

Water jet cutting provides benefits with respect to the

surface, because depending on the process there are no

weld spatters and no burr formation.

The part can also be processed further without thermal

heat treatment and straightening.

PROCESS COMPARISON

WATER JETS VS. ELECTRICAL DISCHARGE MACHINING

Water jets are much faster than EDM

Water jets machine has a wider variety of materials (virtually any material).

Uniformity of material is not very important to a water jet.

Water jets do not heat the surface of what they machine.

water jets require less setup and can cut even non conducting materials.

water jets can be considered to be like super-fast EDM machines with less

precision.

COMPARISON OF COMPONENT

SURFACE

20 mm mild steel, cut with the abrasive water jet (left)

and the laser jet (right)

STRUCTURE ANALYSIS

Water jet cutting is a cold process, so there is no structural

influence.

The heat transfer during laser, plasma and flame cutting

changes the structure

ENVIRONMENTAL ISSUES AND

FUTURE Nowadays, every manufacturing process is being re-evaluated in

terms of its impact on the environment. For example, use of

conventional coolants in machining and grinding is being looked upon

critically from the point of view of its impact on environment. The

environmental issues relevant to AWJM are,

• water recycling

• spent water disposal

• chip recovery

• abrasive recovery and reuse

Environmental issues and concerns have lead the researchers to use

such mediums and abrasives that do not require disposal, recycling or

lead to pollution. Work is going on in the area of high-pressure

cryogenic jet machining .

CRYOGENIC ABRASIVE JET MACHINING

In Cryogenic Abrasive Jet

Machining, liquid nitrogen

replaces the water phase and dry

ice crystals (solid CO2 crystals)

replace the abrasive phase leading

to no need of disposal or waste

generation.

The removed work material in

the form of microchips can be

collected much easily reducing

the chances of environmental

degradation.

MATERIALS, WHICH ARE GENERALLY

MACHINED USING WJ AND AWJ

Steels

Non-ferrous alloys

Ti alloys, Ni- alloys

Polymers

Honeycombs

Metal Matrix Composite

Ceramic Matrix Composite

Concrete

Stone

Granite

Wood

Reinforced plastics

APPLICATIONS

• Paint removal

• Cleaning

• Cutting soft materials

• Cutting frozen meat

• Textile, Leather industry

• Surgery

• Cutting

• Drilling

• Turning

• Glass Fiber Metal

APPLICATIONS

Aerospac

e

Food Processing

Marble Industry

APPLICATIONS

Automotive Electronics and

PCBs

Concrete

Ceramic part cut with an abrasive

water jet

Steel gear and rack cut with an

abrasive water jet

APPLICATIONS

PARTS MADE BY WJM

STAINLESS STEEL MILD STEEL

HARDENED STEEL ALUMINUM

TITANIUMCOPPER

CERAMICSTONE

WOOD RUBBER