US20060223423A1

US20060223423A1 - High pressure abrasive-liquid jet

Info

Publication number: US20060223423A1
Application number: US11/399,565
Authority: US
Inventors: Benjamin Dorfman; Steven Rohring
Original assignee: United Materials International LLC
Current assignee: United Materials International LLC
Priority date: 2005-04-05
Filing date: 2006-04-05
Publication date: 2006-10-05

Abstract

An abrasive-liquid jet cutting head comprising at least one mixing stage; a first mixing chamber arranged to accept a coherent high pressure liquid from an orifice and flow of accelerated abrasive particles from an abrasive feed tube and produce a pressurized slurry-like flow that enters a nozzle; wherein a nozzle to orifice ratio is in a range of about 1.2:1 to 2.49:1 wherein nozzle opening size to orifice opening size is 1.2 to 2.49 times larger in size.

Description

This application claims priority of United States Provisional Patent Application to Benjamin F. Dorfinan and Steven A. Rohring, Ser. No. 60/668,453 for METHODS FOR IMPROVING ABRASIVE JET TECHNOLOGY AND APPARATUS FOR THE SAME, filed on Apr. 5, 2005.

FIELD OF INVENTION

The invention relates to the field of high-pressure abrasive-liquid jet (also sometimes known as ‘Abrasive Waterjet’ or ‘Abrasivejet’) technology often used in material removal, and more specifically, improvements upon conventional abrasive-liquid jet technology in the area of cutting head assemblies considering the important relationship between cutting head components of Orifices and Nozzles (also known as Focusing Tubes or Mixing Tubes).

BACKGROUND OF THE INVENTION

Conventional abrasivejet technology is used to cut a variety of materials but is found to be highly inefficient in the use of energy and resources mainly due to cutting head design limitations that incorporate a 3:1 nozzle to orifice ratio. Conventional abrasivejet is also currently limited to perform one purpose at a time such as thru cutting of material or surface removal of material as there are not any abrasivejet systems currently producing useful byproducts simultaneously with the initial purpose of material removal. This is primarily due to the widespread acceptance of garnet as the preferred abrasive for almost all conventional applications.
A high-pressure pump is utilized to generate fluid pressure, usually above 30,000 psi, and preferably with water or water with additives as the liquid medium. The pressurized liquid is then transported at high velocities through tubing to a cutting head that mainly consists of an orifice to deliver the liquid, an abrasive feed tube, a mixing chamber where the liquid and abrasive are mixed, and a nozzle (sometimes called a focusing tube or a mixing tube) that finally directs the abrasivejet stream onto the subject material that is to be removed.
Currently, there are not any significant differences between any cutting heads or techniques of conventional abrasivejet equipment manufacturers, as generally all orifice, nozzle, and abrasive materials incorporated are the same for each manufacturer. Orifices are usually made from hard materials such as diamond or sapphire that generally produce a non-laminar jet. Nozzles are mostly made from a very hard tungsten carbide. Conventional abrasivejet equipment manufacturers also have similar cutting head designs with non-significant variations between each design. These cutting head designs have been widely demonstrated to cut at speeds within 30% of each other with similar surface finishes in comparative testing when equal parameters were used.
A more important similarity, as well as deficiency, of conventional abrasivejet technology is the widespread use of garnet abrasives over all other abrasives. Garnet is widely used because of its initial low cost and ability to cut a wide range of subject materials, however, it is widely used mainly because of its lower overall costs when compared to other conventional abrasives.
Conventional abrasivejet technology does not effectively use abrasives other than garnet due to numerous factors such as higher initial costs of most other hard abrasives compared to garnet and the inability of other hard abrasives to cut significantly faster than garnet. These factors generally result in higher overall costs of abrasive consumption after considering the final amount of material cut. There is also the limitation of conventional abrasivejet cutting head technology preventing use of harder abrasives than garnet because of the increased costs of accelerated nozzle wear created by these harder abrasives.
The similarities of conventional cutting head designs' primary use of only one type of nozzle material, use of only one abrasive medium, and use of only two types of orifice materials, mainly produce a common limitation of an approximate 3:1 nozzle to orifice ratio. This means the bore of the nozzle is generally three times larger than the diameter of the orifice. The volume of the abrasivejet stream inside the bore of the nozzle consists of an air, high-pressure liquid and abrasive mixture, with a relatively low amount of high-pressure liquid. The liquid is where the process energy originates in the cutting head. Therefore, a relatively larger volume of area in the nozzle bore compared to the smaller area of volume of the liquid energy creates inefficiencies.
A solution to create a more efficient use of energy would incorporate a smaller nozzle to orifice ratio such as 2:1 but this solution is not currently viable with use of conventional cutting heads and garnet abrasives. The best solution for conventional technology has been use of relatively small volumes of high-pressure liquid in the abrasivejet mixture allowing for viable cutting, but this also reduces the effective cutting energy by being dispersed over a greater area, hence, the effective energy is not optimally focused.
U.S. Pat. Nos. 3,424,386, 3,972,150, 4,080,762 and 4,125,969 all teach the abrasive (sand) stream to be in the central portion of the nozzle while the pressurized fluid is introduced into the peripheral area surrounding the central sand stream. A ring orifice plate or disk such as employed in the U.S. Pat. Nos. 3,424,386, 4,080,762 and 4,125,969 to provide the fluid jets around the sand stream has many disadvantages including: the introduction of pressurized fluid tangentially into a nozzle a short distance above the orifice disk is not conducive to the generation of a coherent fluid jet due to flow disturbances upstream of the orifices; sand in the central portion of a nozzle creates an abrasive environment that can weaken the interior wall of the annular fluid chamber without being detected; pressurized fluid in the outer annular space results in a nozzle that is very large in dimensions as both interior and exterior walls must be sized to accommodate the fluid pressure; and sealing the annular orifice disk can be very troublesome. The U.S. Pat. No. 3,994,097 teaches a centrally located water jet while sand is fed into a nozzle chamber through a single sand passageway. The sand is forced into the water jet by passage through a conical nozzle. This patent recognizes abrasion problems within the nozzle and the necessity of exact alignment. These problems would be intensified at higher pressures. All of these patents teach mixing abrasive into water by (1) intercepting an abrasive stream with water jets, and (2) forcing abrasives, water and air through a conical nozzle, without concern of fluid actions.
FIG. 1 of U.S. Pat. No. 5,184,434 depicts how the majority of abrasivejet cutting heads are currently designed. The problem areas with the prior art cutting head shown in this patent are the orifice, the mixing chamber and the liquid jet. The orifice is the device where the liquid jet passes through, building up to very high velocities. The mixing chamber is the area where abrasive joins with the liquid jet. A problem with this design is the separation effect of the jet as it starts to break up. The nozzle inlet then receives the stream at various angles and straightens it out while realizing considerable wear on its bore. FIG. 2 of U.S. Pat. No. 5,184,434 depicts the art of Abrasive Suspension Jet (sometimes called “Slurry Jet”) cutting. This method adds abrasive to the stream before entering the orifice. The advantage of this method is that it produces a coherent jet, but the disadvantage is that components such as tubing, valves and orifices wear out quickly due to the abrasive suspension inside the system severely eroding everything it contacts.
Another disadvantage of the orifice designs in conventional abrasivejet is the sharp transition from the pump tubing to the relatively small orifice. This sharp transition creates a high resistance of the pressure flow and does not allow for properly formed liquid optimization, resulting with jet distortion, and decrease in overall energy efficiency of the system.
Garnet is conventionally used because it does not wear the nozzles out significantly even with the non-laminar jet produced a conventional orifice as shown in FIG. 1 of U.S. Pat. No. 5,184,434. Garnet also has a low initial cost and it is effective in cutting a wide range of materials without significantly wearing the nozzle while using the standard 3:1 nozzle to orifice size ratio. These factors allow for a lower overall cost compared to other abrasives and have allowed garnet to be the primary abrasive medium used for almost all abrasivejet applications. However, there are many reasons why garnet is not the optimum abrasive available when considering the complete abrasivejet system, recycling and the ability to perform two or more processes in one operation.
One reason is that garnet is not the optimum abrasive is because it is not effectively recyclable. It is widely accepted that only 30% to 50% of larger garnet particles can be reclaimed for reuse after a single cutting operation as most of the garnet particles are reduced in size from fracturing upon impact and made less effective for further cutting of subject materials. Current recycling processes of garnet generally add unused larger particles to the reclaimed particles in order to keep cutting speeds at an acceptable level.
Another disadvantage is that very hard subject materials such as carbides and hard ceramics are generally not cut with abrasivejet technology because of the very low cutting speed ability of garnet to cut these materials. Conventional abrasivejet techniques also have problems with feeding heavier abrasives because of the inherent design limitation of a large nozzle to orifice ratio. A major problem with prior art is the high concentration of air in the abrasivejet that significantly reduces the overall energy for cutting or treating. However, the greatest problem with prior art is the relatively slower speeds of abrasive particles compared to the initial speed of the liquid jet. The air and abrasive mixture introduced in the mixing chamber never completely suspend with the liquid jet.
Thus it is readily apparent that there is a long felt need for an abrasivejet cutting head that can cut subject materials more effectively by a high-pressure liquid jet that incorporates a nozzle to orifice ratio of less than 2.5 to 1 that can reduce overall costs and increase process speeds and obtain faster abrasive velocities to achieve faster cutting or treatment rates. There is also a need to expand abrasivejet into new applications.

SUMMARY OF THE INVENTION

The present invention is a new cutting head approach for the effective formation of a high pressure abrasive-liquid mixture. The mixture is made more effective over prior art by focusing of the abrasivejet energy into a smaller area through utilizing a small nozzle to orifice ratio less than 2.5:1. This means that the bore of the nozzle is less than 2.5 times larger than the diameter of the orifice in order to concentrate the abrasivejet energy into a smaller area when compared to prior art that specifies a 2.5:1 or greater nozzle to orifice ratio (primarily 3:1). A smaller nozzle to orifice ratio is desired in order to create more impact energy for faster processing of materials. Improvements are disclosed herein describing more efficient use of energy and resources compared to current abrasivejet technology. These improvements are obtained by: use of specially engineered abrasive particles with specific properties, and proper mixture of these particles in the abrasivejet stream; optimization of individual components of the cutting head, and optimization of their relationships to each other as a complete system.
An abrasive-liquid jet cutting head comprising at least one mixing stage; a first mixing chamber arranged to accept a coherent high pressure liquid from an orifice and flow of accelerated abrasive particles from an abrasive feed tube and produce a pressurized slurry-like flow that enters a nozzle; wherein a nozzle to orifice ratio is in a range of about 1.2:1 to 2.49:1 wherein nozzle opening size to orifice opening size is 1.2 to 2.49 times larger in size.
It is a general object of the present invention to provide an improved cutting head with a smaller nozzle to orifice ratio in order to create more impact energy for faster processing of materials.
Another object of the present invention is to provide an improved cutting head using non-conventional abrasives along with optimized cutting head configurations to allow for improvements to traditional abrasivejet applications along with creating new applications currently not associated with conventional abrasivejet.
Another object of the present invention is to provide an improved cutting head to process subject materials more efficiently through optimization of the abrasive mixture process into a liquid jet stream, resulting with reduced overall costs of the abrasivejet technique for cutting or other material removing technology, as well as surface treatment.
Yet another object of the present invention is to provide a cutting head that provides improvements to the abrasivejet technique to achieve increased processing speeds, better tolerances and better quality surface finish of subject.
Still another object of the present invention is to provide a cutting head that fosters the creation of several novel manufacturing.
A further object of the present invention is to provide a cutting head that facilitates faster particle acceleration for a more effective mixing of non-traditional heavy metallic abrasive particles with the waterjet, resulting in lower costs, recycling of the heavier abrasive particles and greater cutting speeds.
Yet another object of the present intention is to provide a cutting head comprised of a solid component.
Another object of the present invention is to provide a cutting head produced from modular components.
These and other objects, features, and advantages of the present invention will become apparent upon a reading of the detailed description and claims in view of the several drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1—A perspective view of a solid component abrasivejet cutting head.
FIG. 2—A perspective view of a modular component abrasivejet cutting head.

DETAILED DESCRIPTION OF THE INVENTION

At the outset, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions, or surfaces consistently throughout the several drawing figures, as may be further described or explained by the entire written specification of which this detailed description is an integral part. The drawings are intended to be read together with the specification and are to be construed as a portion of the entire “written description” of this invention as required by 35 U.S.C. §112.
For purposes of this patent, the terms appearing below in the description and the claims are intended to have the following meanings:
“Abrasive” means any particulate material intentionally introduced into a pressurized liquid jet in the form of sharp edge particles, such as angular, cubical, or non-spherical shapes, generally used for material removal or surface treatment upon interaction with subject material.
“Abrasivejet” means a mixture of a high pressure liquid jet stream and abrasive particles focused through a nozzle to provide for a useful tool.
“Subject material” means any material intentionally exposed to the impact of a pressurized liquid jet carrying particles of abrasive material.
“Waterjet” means a pressurized liquid stream generated by a pump, distributed by high pressure tubing, and then focused through an orifice to create a useful tool for cutting or surface treatment.
“Nozzle” means a channel that mixes abrasive with a pressurized liquid jet and focuses the abrasivejet in a concentrated stream upon exit of the nozzle tip (a nozzle is also known as a focusing tube or mixing tube). The smallest opening of the channel is the specified size of the nozzle. The specified size of the nozzle is important in determining the nozzle to orifice ratio, as all of the abrasivejet is focused into the smallest area.
“Orifice” means an opening that accepts a pressurized liquid stream and allows it to pass thru. The opening is generally specified as a diameter. The selection of the orifice size generally determines the output pressure of the high pressure system based upon the capabilities of the pump and the operating speed of the pump.
“Cutting Head” means a device used in an abrasivejet system that contains an orifice aligned to a nozzle, whereas the orifice produces a jet that is directed into the central channel area of the nozzle. The cutting head allows for the establishment of the nozzle to orifice ratio after the nozzle and orifice are installed into the cutting head.
“Nozzle to Orifice Ratio” means the total area of the smallest opening of the channel in a nozzle compared to the total area of the smallest opening of the orifice. Generally, the openings for nozzles and orifices are cylindrical in shape. For example, a conventional abrasivejet cutting head of prior art would utilize a 0.030″ diameter nozzle if a 0.010″ diameter orifice were installed, thus realizing a 3:1 nozzle to orifice ratio.
“High-Pressure” means a liquid pressure exceeding 10,000 psi.
“Surface Treatment” means intentional change of any characteristics of materials subjected to the impact of pressurized liquid jet carrying particles of abrasive material. Treatment may be realized by partial removing of subject material and/or change of its surface morphology (such as polishing or etching), and/or superficial structure, such as size and shape of its superficial grains, generating dislocations and/or other structural defects, and/or superficial composition of subject material by the impact of pressurized abrasive-liquid jet. Treatment may be resulted with pre-designed cutting or other change of geometrical shape of subject material or with an intentional change of its superficial mechanical properties (such as hardness), and/or tribological, and/or physicochemical, and/or electrochemical and corrosion resistance properties, and/or catalytic properties, and or external appearance, reflectivity or color.
“Coherent Jet” means a highly focused, laminar or nearly laminar high pressure stream generated by an orifice that produces centrally concentrated energy into the nozzle. Standard sapphire or diamond sharp-edge orifices used in conventional art do not produce a coherent jet without additional modifications to the jet below the opening. It is preferred that an orifice produces a coherent jet without any additional modifications to the jet in order to achieve higher efficiency.
Improvements to abrasive particle selection through the implementation of pre-engineered abrasives with high recyclability and greater density are determined to be the optimum solution for most abrasivejet applications. Greater amounts of cutting energy are transmitted when a good mixture of these heavier particles are mixed properly with a waterjet. The kinetic energy of the impact against a subject material is improved when these particles are accelerated to the speed of the waterjet. This can only occur with a good suspension, or mixture, of the particles entrained into a water jet. The present invention is a specialized cutting head with a nozzle to orifice ratio in operatively arranged to create more impact energy for faster processing of materials. A cutting head with the ability to allow higher velocities and energy of the particles. In accordance with the present invention, subject materials may be cut more effectively by a high pressure liquid jet mixed with abrasive particles in a concentration by utilizing smaller nozzle to orifice ratios than proposed with prior art.
Adverting now to the drawings, FIG. 1 is a perspective view of the present invention showing a solid component cutting head 10, which, in one embodiment, comprises solid member 30 which is the main body of the cutting head and has at least one abrasive feed tube 16; wherein the mixing chamber 24 is arranged to accept a flow of accelerated abrasive particles from at least one abrasive feed tube 16 (also referred to as an abrasive inlet) and a pressurized liquid flow from orifice 20 wherein a pressurized slurry-like flow is generated. The mixing chamber 24 associated with one or more feed tubes is arranged to introduce the slurry-like flow and focus that flow through nozzle 12 for the purpose of cutting or treating. The type of materials used to make solid member 30 may vary depending on the abrasive used and the desired output. Orifice 20 may be polished to achieve higher surface finished quality if the manufacturing process, such as injection molding/sintering, does not yield suitable water jet quality.
Nozzle 12 has a cylindrical opening the size of which is preferably at a ratio less than 2.5 times smaller in size than orifice 20. In the mixing chamber the pressurized slurry-like flow mixes the liquid energy and abrasive mass to allow for greater effective transfer of energy, thus providing the higher energy efficiency of the entire cutting process. The density of water is far less than the desired abrasives, thus making the mixture of abrasives into the liquid jet stream difficult. The speed of water is also orders of magnitude higher than the speed of the abrasive particles introduced into the stream. The abrasive does not naturally enter the stream in these difficult cases, thus a nozzle is used to mix and focus the liquid jet with the abrasives in order to create a good abrasive suspension in the jet. It is preferable that the nozzle is less than 2.5 times smaller in size than the orifice in order to allow for a more effective mixture of abrasives with the liquid jet.
The purpose of this design is to reduce costs through the utilization of injection molding. Various hard materials such as ceramics, nitrides and carbides can be injection molded in order to reduce costs. Suitable hard materials may include, but are not limited to, tungsten carbide, silicon carbide, alumina, or zirconia.
Although the solid component cutting head 10 of the embodiment, as shown in FIG. 1, is formed in a unitary construction as a single molded unit wherein solid member 30 cutting head must be attached to a sleeve or a suitable body it should be understood, that other constructions may be used without departing from the invention. For example, the modular component cutting head 10 having an interchangeable cutting head body 22 as is shown in FIG. 2. The supporting sleeve or body for either embodiment must then be connected to a high pressure system via any suitable method to seal in the pressurized liquid in order that the liquid may only pass through the orifice. High pressure tubing, fittings, valves or adaptors can be connected to a multi-stage cutting head 10 by various sealing methods to accomplish this requirement. Nozzle nut 28 of FIG. 2 holds the interchangeable components in place and also may allow for sealing to take place.
Both the single component unit, and the interchangeable modular component unit, cutting heads 10, utilize a nozzle to orifice ratio of less than 2.5:1. Although different configurations or designs for the instant intervention can be utilized, the significant feature of the invention is the nozzle to orifice ratio.
Different styles of cutting head 10 may utilize similar orifice 20 geometries or different geometries of conventional or non-conventional design. However, an orifice with an efficient coefficient of discharge of at least 85% is preferred over industrial standard orifices that have sharp-edges producing lower efficiency discharge coefficients. Although it is preferred to utilize higher efficiency orifices, any reasonable orifice design can be utilized in order to achieve the desired nozzle to orifice ratios. In some cases, modifications to the orifice or liquid jet can be made in order to produce a more coherent stream. For example, an industry standard orifice that produces a non-laminar jet can be used if the jet is redirected into a more coherent flow to be utilized in small nozzle to orifice ratios.
The modular component multi-stage cutting head 10 having an interchangeable cutting head body 22 as shown in FIG. 2 offers greater flexibility of use than the solid member style cutting head. First, a modular component is not limited to materials that can only be used for injection molded units. Second, it offers the ability to interchange orifice 20 or nozzle 12 components for various applications that may require certain abrasive materials, or different results. Third, it offers modularity by providing for more orifice and nozzle combinations and ratios without the need for as extensive inventory.
Also in accordance with the present invention, two or more different abrasive materials may be combined in one abrasive jet. The abrasive materials may differentiate in size of particles, and/or in density (specific gravity) of particles, and/or other physical properties of particles, such ductility vs. brittleness.
The cutting head may be fed with abrasive particles from any abrasive material selected from, but not limited to, the following groups of abrasive materials: the first abrasive group comprising glass, obsidian, quartz, aluminum oxide, boron carbide and silicon carbide; the second abrasive group comprising: garnet, olivine, chromite, ilmenite, rutile, pyrite, zircon, hematite, magnetite; the third abrasive group comprising: cassiterite, metals, steel, alloys; the fourth abrasive group comprising: hard melting heavy metals including but not limited to: tungsten, molybdenum, tantalum and/or respective carbides.
The use of heavier abrasive particles, such as stainless steel material, with higher fracture toughness compared to garnet, allow for lower overall costs through optimization of the entire abrasive jet process that garnet or other conventional abrasives cannot achieve. Through the effective mixture of select abrasive particles with a small nozzle to orifice ratio approach, improvements to the abrasive jet cutting process can be achieved allowing for abrasive jet to become a highly productive and efficient technology.
The ultimate goal of abrasivejet cutting technology is to provide a satisfactory quality surface finish onto the subject material at the lowest possible cost. Thru cutting of the subject material in length of travel is the predominant use of the cutting tool; typically, removing of a wider channel of material is not required or desired. By focusing of the abrasivejet particle energy into a smaller diameter nozzle, less width of cutting is produced but longer lengths of travel are experienced with the same amount of possible liquid energy from the pump. The output pressure and flow rate of the pump is limited at the maximum capability of the pump but the cutting head is the apparatus that efficiently or inefficiently utilizes the same amount of fixed liquid energy to produce abrasivejet cutting energy.
Still another feature of the invention is the specifically designed orifice 20 that increases effective cutting energy, efficiency, and life of the nozzle by minimizing wear in comparison to conventional orifices. The angle of jet impact inside the bore of the nozzle is minimized through the utilization of an orifice that produces a coherent jet stream. The concentration of the coherent stream combined with a small nozzle to orifice ratio allows for a higher vacuum to mix particles in the liquid jet stream, and allows for reduced negative effects of air mixed into the abrasivejet. These improvements allow for greater energy when a more concentrated mixture of abrasive and liquid is achieved, and less air volume is obtained. The coherent stream also allows for less wear of the nozzle, faster process speeds, and use of harder abrasive materials than garnet.
Empirical evidence demonstrates that an increase in cutting speeds can be achieved while using the proposed smaller nozzle to orifice ratio. For example, garnet 80 mesh abrasive was used at a rate of 1 lb/min to cut a 0.50″ thick 4140 annealed steel plate at 8 ipm (inches per minute). The orifice used was 0.013″ diameter with a 52,000 psi waterjet generated. The nozzle used was 0.040″ diameter, thus an approximate 3:1 nozzle to orifice ratio was used. Using the exact same conditions, the abrasive was switched to HG80 steel grit at the same rate of 1 lb/min. A slightly improved cutting speed was achieved at 8.5 ipm, probably because of the increased density of the steel over garnet. However, when the conditions changed to a use a smaller nozzle of 0.030″ and only a half pound of steel grit per minute instead of one, the cutting speed increased to 10 ipm of the same 4140 steel plate with the same jet conditions. The effect of using a cutting head with a 2.3:1 nozzle to orifice ratio is an increase in focus, mixture and acceleration of the steel particles and thus increased efficiency, lower costs, and improved process speed.
When any hard abrasives such as garnet are used in a cutting head, smaller nozzle restriction is detrimental to nozzle wear. Thus a cutting head of the preferred invention, with smaller nozzle to orifice ratios configurations, can be used with abrasives that are softer than garnet, such as steel, and do not wear the nozzle as quickly.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Claims

1. A abrasive-liquid jet cutting head comprising:

an orifice aligned to a nozzle;

at least one mixing stage;

a first mixing chamber arranged to accept a coherent high pressure liquid from said orifice and flow of accelerated abrasive particles from an abrasive feed tube and deliver said liquid and said abrasive into an inlet of said nozzle;

an abrasive liquid jet produced by said nozzle wherein a nozzle to orifice ratio is established in a range of 1.2:1 to 2.49:1 wherein nozzle opening size to orifice opening size is 1.2 to 2.49 times larger in size.

2. An abrasive-liquid jet cutting head according to claim 1 with liquid operating parameters at 0.1 gpm to 10 gpm at high pressures of 10,000 psi to 150,000 psi, and abrasive feed rates of 0.05 lb/min to 5 lb/min.

3. An abrasive-liquid jet cutting head according to claim 1 wherein said abrasive particles have a specific gravity of 4.0 and higher.

4. An abrasive-liquid jet cutting head according to claim 3 to wherein said abrasive particles metallic elements taken from a group consisting of metals, alloys, steel, metal oxides, and metallic carbides.

5. An abrasive-liquid jet cutting head according to claim 1 using an orifice with a coefficient of discharge between 85% to 99.99%.

6. An abrasive-liquid jet cutting head according to claim 1 using an orifice with a coefficient of discharge between 60% to 85%.

7. An abrasive-liquid jet cutting head according to claim 1 having a solid body for said cutting head is manufactured using injection molding and sintering techniques.

8. An abrasive-liquid jet cutting head according to claim 7 where the materials used for injection molding are hard ceramic materials, including oxides and nitrides, or hard carbide materials.

9. A method for producing a high velocity abrasive liquid jet utilizing a cutting head with an orifice aligned to a nozzle with a defined nozzle to orifice ratio of 1.2:1 to 2.49:1, being that the nozzle is 1.2 to 2.49 times larger in size than the orifice.