WATER JET CUTTING TECHNOLOGY

 

WATER JET CUTTING TECHNOLOGY

CONTENTS

l INTRODUCTION

l TYPES

l BASIC EQUIPMENT USED

l EFFECTS OF EQUIPMENT VARIATION

l APPLICATIONS

l ADVANTAGES

l DISADVANTAGES

l REFERENCES

 

INTRODUCTION

lThe constant volume of water traveling through a reduced cross section area causes the particles to rapidly accelerate. This accelerated stream leaving the nozzle impacts the material to be cut. The extreme pressure of the accelerated water particles contacts a small area of the work piece. In this small area the work piece develops small cracks due to stream impact. The water jet washes away the material that “erodes’ from the surface of the work piece.

TYPES

lABRASIVE WATERJETS

lSlurry:

     An abrasive water jet slurry system mixes the abrasive with the water jet early in the system. This is done before the water is pressurized. Slurry systems then accelerate the abrasive particles with the water throughout the system. This causes more wear on the internal parts than an entrainment system.

lEntrainment:

     An abrasive water jet entrainment system mixes the abrasive with the water jet in a mixing chamber just after the nozzle. In most systems being built today, a venturi effect is utilized to pull the abrasive into the water jet. The abrasive particles are accelerated into the stream and then with the stream out the orifice.

 

lABRASIVE WATER SUSPENSION JETS

 

     An abrasive water suspension jet system accelerates a suspension of abrasive in water through the system. This type of system appears to be more efficient than previously developed abrasive water jet systems

BASIC EQUIPMENT USED

l CNC guide machine

l PC based programmable controller or microprocessor based control

l Structural steel Base

l Servo drive system

l X/Y” carriage

l Cantilever arm

l Motorized “Z” axis

l Catch tank

l Cutting table

l Work piece support grid/material

l Filtration system

l High pressure pumps

l Pressure intensifiers

l Abrasive material disposal/removal system

l Injector to draw abrasives into cutting stream

AFFECTS OF EQUIPMENT VARIATION

 

Nozzle Opening Shape:

l This allows the user to create slightly different shaped cut.

l It can also help accelerate the abrasives in the mixing tube.

l Finer openings allow more precise cutting and accelerated water jets.

 

Size and Shape of the Orifice:

l This allows the user to better control the mixture of the abrasive and water.

 

Multiple Nozzles:

l Can better control hole shape and depth of cut.

l Decreases the pressure if multiple nozzles are put on one pressure intensifier.

l Smooth rounded finish to glass (and other materials) therefore the edge does not have to be re-ground.

 

Pressure Intensifiers:

l The size of the pressure intensifier varies approximately from 20,000psi to 50,000psi.

l Allows variation in cutting..

 

APPLICATIONS

l Water jet cutting is used mostly to cut lower strength materials such as wood, plastics, and aluminum. When abrasives are added, stronger materials such as steel, and even some tool steels can be cut, although the applications are somewhat limited. Listed below are different applications, and reasons why water jet cutting is used for each one.

 

l Wire Stripping: Wire stripping is another application that can be used effectively in water jet cutting. If no abrasives are used, the stream is powerful enough to remove any insulation from wires, without damaging the wires themselves. It is also much faster and efficient than using human power to strip wires.

 

l Tool Steel: For abrasive water jet cutting, tool steels are one application, although a limited one. It can be very useful though because tool steel is generally very difficult to cut with conventional machining methods, and may cause an unwanted byproduct: heat. Abrasive water jets, however, do not produce heat that could alter the structure of the material being cut, and thus the strength of the tool is retained.

ADVANTAGES

lIn water jet cutting, there is no heat generated. This is especially useful for cutting tool steel and other metals where excessive heat may change the properties of the material.

 

lUnlike machining or grinding, water jet cutting does not produce any dust or particles that are harmful if inhaled.

 

lDrawing detailed prints of a part and then having a machinist cut the part out

DISADVANTAGES

lOne of the main disadvantages of water jet 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, water jet cutting can be very costly and outweigh the advantages.

 

lAnother disadvantage is that very thick parts can not be cut with water jet cutting and still hold dimensional accuracy. If the part is too thick, the jet may dissipate some, and cause it to cut on a diagonal, or to have a wider cut at the bottom of the part than the top. It can also cause a ruff wave pattern on the cut surface.

REFERENCES

lTreanor, Brian, Aspects of alterity: Levinas, Marcel, and the contemporary debate, Fordham University Press, 2006, p.41

lKlein, Ernest, A comprehensive etymological dictionary of the English language, Vol II, Elsevier publishing company, Amsterdam, 1969, p.1317

lEngle, Eric, Lex Naturalis, Ius Naturalis: Law as Positive Reasoning & Natural Rationality, The Rlias Clark Group, Melbourne, 2010, p.75

lReimer, Marga (2009). "Reference". Stanford Encyclopedia of Philosophy

lSaeed, John, Semantics, Blackwell, p. 12, ISBN 0-631-22693-1