Abrasive Suspension Jet Research Articles

Mathematical model for abrasive suspension jet cutting based on orthogonal test design

This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet (ASJ) cutting process and construct its cutting model. Orthogonal test design is applied to cutting stainless steel. Through range analysis on experiment results, the optimal process conditions for the cutting depth and the kerf ratio of the bottom width to the top width can be determined. In addition, the analysis of ranges and variances are all employed to identify various factors: traverse rate, working pressure, nozzle diameter, standoff distance which denote the importance order of the cutting parameters affecting cutting depth and the kerf ratio of the bottom width to the top width. Furthermore, non-linear regression analysis is used to establish the mathematical models of the cutting parameters based on the cutting depth and the kerf ratio. Finally, the verification experiments of cutting parameters’ effect on cutting performance, which show that optimized cutting parameters and cutting model can significantly improve the prediction of the cutting ability and quality of ASJ.

Effect of Slurry and Nozzle on Hole Machining of Glass by Micro Abrasive Suspension Jets

Micro drilling experiments of glass by Micro Abrasive Suspension Jets (MASJ) were carried out. The influence of the nozzle and compositions of slurry including the selection of abrasives, suspending agents and their concentrations on material removal, the depth and the diameter of the machined holes were investigated for glass drilling. Four processing stages are provided to describe the erosion profile characteristics. The suspension properties of slurry play an important role in MASJ machining. Five million molecular weight non-ionic polyacrylamide with concentration of 0.6% , white corundum abrasive and the longest length of the nozzle cylindercal zone can achieve lager material removal and better quality of hole in MASJ machining.

Techniques de découpage télé-opérées dans le domaine du déclassement nucléaire

Remote disassembly of radiologically burdened large components is among the most sophisticated and complex activities in the dismantling of nuclear installations. High local dose rates and contamination levels in combination with poor accessibility and complex geometries of parts imply major challenges.In many cases the design of nuclear reactors makes use of the shielding effect of water during operation. Hence, also in the later nuclear decommissioning it is possible to make benefit of this effect by dismantling/cutting of equipment under water. In the opposite, in some other cases of nuclear reactor design no shielding water is used during operation, and thus, also decommissioning activities have to focus exclusively on dry dismantling techniques to avoid, amongst others, the production of wet secondary waste.These and several other parameters entail the application of different cutting technologies thoroughly adjusted to the particular requirements.This article describes three thermal and one nonthermal cutting technology which have been effectively applied in nuclear decommissioning projects. The thermal cutting technologies addressed are “Autogenous Flame Cutting”, “Plasma Arc Cutting” and “Contact Arc Metal Cutting”. The non-thermal cutting technology addressed is “High Pressure Water Jet Cutting”.With the exception of Contact Arc Metal Cutting, all of these technologies are well known and prooven in the field of manufacturing. Nevertheless, to cope with the challenges in the field of nuclear decommissioning, it is also very important to combine the cutting technology/cutting equipment correctly with the remote controlled handling systems.At first the basic functioning will be described for understanding of the technologies themselves. The functioning accounts different fields of application and the particular technological limits. Adaptations for nuclear decommissioning requirements will be described presenting the most important modifications.At second applications and gained experience in particular nuclear decommissioning projects will be present by pictures and/or short videos.As conclusion details and data of all addressed cutting technologies will be presented in a matrix, giving a hand to concerned engineers in the selection of best matching technologies for particular nuclear decommissioning activities.<b>Short description of the different cutting technologies<b/>Autogenous Flame CuttingThe Autogenous Flame Cutting Technology has been introduced more than 100 years ago and has been developed to a standard method for the cutting of mild steel. A high pressure oxygen jet oxidises the material in a small kerf. Nevertheless, not all metal types are appropriate for the autogenous cutting process.Which are the limiting factors of the Autogenous Flame Cutting Technology? How can normally non-suitable material be cut anyhow? What is the maximum achievable cutting speed? Which peripheral equipment is necessary?Plasma Arc CuttingIn the nineteen-fifties the Plasma Arc Cutting Technology has been introduced as a complementary technology, to cope also with material unsuitable for flame cutting (for example stainless steel, copper, etc.).In contrast to Autogenous Flame Cutting, the Plasma Arc Cutting uses an electronically induced plasma arc to melt a kerf in the material. Inside the plasma arc temperatures up to 30.000 Kelvin exist. In theory, this temperature is sufficient to cut all materials. But where are the limits in practise?For nuclear decommissioning the Under-Water Plasma Arc Cutting Technology is important. Special equipment allows cutting under water, reducing the radiation impact to the concerned staff. Also the release of dust and particles to the air is reduced by 99.4 %.Contact Arc Metal CuttingContact Arc Metal Cutting is a new thermal cutting technology for under-water cutting jobs. In opposite to the previously introduced cutting technologies, here a carbon blade cuts the components. An electric arc between cutting blade and component melts the kerf into the material like a hot knife into a piece of butter.With the Contact Arc Cutting Technology it is now possible to cut also complex structures (structures with hollows and undercuts).How exact is the technology? Which applications are possible and where are the limits? The article will answer this and other questions.Water Jet Cutting(High Pressure) Water Jet Cutting can be distinguished in Pure Water Jet Cutting and Water Jet Cutting with additional abrasive particles. Both cutting principles use high pressure pumps to create the required high water pressure. In a special nozzle the water pressure is transformed into a high speed water jet (achieving speeds of several hundred meters per second). Nevertheless, cutting of metal or concrete requires the adding of abrasive particles to the water jet.There are two different technical solutions of Water Jet Cutting with additional abrasive particles. The Water Abrasive Injection Jet Cutting technology and the Water Abrasive Suspension Jet Cutting technology.The technological differences between the two technologies will be explained. Advantages for nuclear decommissioning projects and required peripheric equipment are explained in the article.

Hole Machining of Glass by Micro Abrasive Suspension Jets

Abrasive Suspension Jets (ASJ) is a new micro processing technique developed for micro processing of hard and brittle materials based on the traditional Abrasive Water Jet (AWJ). Based on drilling experiments of glass using MASJ technology, the dependence of material removal, the depth and the diameter of the machined holes on the process parameters, such as working pressure, processing time, standoff distance, incidence angle and concentration of abrasives were investigated. Experimental results show that the material removal is approximately proportional to working pressure, processing time and concentration of abrasives, except the standoff distance. It is founded that the processing time is the most remarkable influence factor on the material removal and the depth of the holes. But the working pressure doesn’t show obvious effects to the material removal and the depth of hole with lower pressure in MASJ. The increase of standoff distance will decrease the material removal and depth of hole, and the concentration of abrasives can improve a few of drilling ability. Further, it is founded that longer processing time and smaller standoff distance will achieve higher MASJ drilling efficiency and better quality of hole, with 90 degree jet incidence angle.

1916 ASJ用鞘付きノズルから噴出するキャビテーション噴流(S21-3 噴流,後流及びはく離流れの流動解析と応用(3),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

An abrasive suspension jet (ASJ) has a greater capacity for drilling and cutting than a conventional abrasive injection jet (AIJ). However, the drilling capability of the ASJ under submerged condition decreases steeply with the increase of the standoff distance. In order to expand the effective standoff distance of the ASJ under submerged condition, a sheathed ASJ nozzle was proposed in the previous paper. In the present paper, observations of the jet issuing from the sheathed nozzle are observed without any abrasive. The injection pressure is set to 5 MPa and the cavitation number is in the range from 0.02 to 0.05. A sheath made of transparent acrylic resin pipe is used and flows in the sheath are observed with high-speed video camera. The results show that a cavity full of vapor is formed in the root part of the sheath. The jet expands fully out to the sheath inner diameter in the region near the sheath exit and a bubbly mixture zone is formed. A cavitation cloud extends from the bubbly mixture zone until to a certain distance of the sheath exit and then break lumps of cavitation bubbles. The bubbly mixture zone in the sheath fluctuates with time and its frequency depends on the cavitation number.

Abrasive Water Suspension Jet Technology Fundamentals, Application and Developments

The introduction of abrasive material into water jet technology in the 80s extended the range of materials, which could be cut to practically all technical materials, which has been one of the largest step of development in this technological branch. Since then, two different types of abrasive water jets developed. Due to their different jet generation these differ in their properties, which define their application fields. Whereas abrasive water injection jets are mainly applied for industrial machining, the core application fields of abrasive water suspension jets are in the decommissioning and dismantling of offshore structures and nuclear power plants as well as in demilitarisation. In this paper the generation mechanisms of abrasive suspension jets are explained, and the influence of the main parameters on the cutting efficiency presented. The properties of this type of jet are marked of those of abrasive water injection jets leading to their specific application fields. Additionally new developments in this technological branch are presented in this paper.

ABRASIVE SUSPENSION JET TECHNOLOGY AND EXPERIMENTAL STUDY ON CUTTING PERFORMANCE

The abrasive suspension jet cutting system at low pressure is presented. In this system, a new type of additive material is adopted in suspension preparation. It has been validated through experiments that this additive material can be used instead of macromolecule polymer. A special high-pressure container is used to transfer the high pressure to the suspension. The suspension is completely separated from medium at high-pressure, and they can be recycled separately. The relation between feed rate and the cut depth is discussed. The cutting abilities of nozzles in different diameter are compared, and the energy consumption rate is analyzed. The results show that the abrasive suspension jet cutting has smaller energy consumption rate, lower cutting cost and better surface quality when compared with the traditional abrasive jet cutting. The advantages are more remarkable when nozzle with smaller diameter is used.

Transient Flow in Abrasive Suspension Jet Cutting Machines on Pump Shutdown

This paper presents an analysis of the transient flow, on pump shut-down, in abrasive suspension jet cutting machines as part of an effort to develop a fine-beam cutting system. The analysis was motivated by a need to clearly understand the problem of line and nozzle clogging, which would be magnified by the higher operating pressures and the use of smaller nozzles for fine-beam systems. Simulation studies show that currently recommended means of avoiding this problem may not be adequate. Using the tools developed for this study, more positive mechanisms and a proposed system to counter this problem were investigated.

Recent Development of New Techniques in Jetting Technology.

The techniques on the continuous water jet and the abrasive entrained water jet have highly developed and applications of the water jet technology have been expanded recently. However, there are some techniques still at the embryo stage which need to be developed for practical applications. Recent developments of new techniques in the jetting technology, pulsed jets, cavitating jets, abrasive suspension jets, ice abrasive jets, and liquefied gas jets, are reviewed in the present report.

Erosion due to Premixed Abrasive Water Jet under Submerged Condition.

It has been shown that the premixed abrasive water jet system, in which an abrasive suspension jet is formed by propelling a premixed abrasive suspension through a nozzle, has a greater capacity for drilling and cutting than the conventional abrasive water jet system. In the present investigation, an apparatus of the premixed abrasive water jet system was constructed for experimental purposes, and the erosion characteristics under submerged conditions were studied. The maximum jetting pressure was 20 MPa. The pressure in the test cell was varied up to 1 MPa. The erosion tests with the cavitating water jet and the submerged abrasive jet were conducted. It is found that the mass loss and the erosion pit depth when using the submerged abrasive jet decrease with increasing stand-off distance and pressure in the test cell. The erosion characteristics due to the submerged abrasive jet is affected greatly by the cavitation phenomenon.