Waterjet Pressures Research Articles

Experimental study of abrasive water jet drilling parameters on UHMWPE for biomedical implant applications

ABSTRACT This study addresses this issue by exploring the effectiveness of abrasive water jet drilling (AWJD) as an unconventional machining approach for UHMWPE. The research employs a full factorial analysis to examine various hole characteristics, including machining time (MT), surface roughness (Ra), taper angle (TA), material removal rate (MRR), and taper ratio (TR). The study aims to understand the effect of the process features, namely abrasive water jet pressures (p), traverse rates (v), and abrasive mass flow rates (ma), on the geometry and position of the drilled holes. The results show that (v) and (p) affect the drilled hole characteristics of surface morphology, roughness, MT, MRR, TA, and TR. The microstructural characteristics of the drilled-hole surfaces are analyzed by scanning electron microscopy (SEM). It revealed that the smooth surface is attained at the lower v of 150 mm/min and ma of 250 g/min.

Effect of thermal cycling on open‐hole tensile strength of sustainable composites: An experimental investigation

AbstractSustainable composites are presently employed in applications where structural demands are minimal. Basalt fiber reinforced PLA (BFPLA) and polybutylene succinate (BFPBS) composites, incorporates bio‐based materials, offer the potential to reduce non‐renewable resource consumption and improve end‐of‐life disposal practices. Given the significance of thermal aging in semi‐structural applications and the necessity for open holes (notches) for installation and assembly, little is known about how thermal cycling (TC) affects the open‐hole strength of sustainable composites. This experimental work establishes a quantitative relationship between open‐hole strength and TC, taking into account varying abrasive waterjet pressures, and explores the impacts of thermal aging on the notch sensitivity, thermal, mechanical, and physical properties. BFPBS displayed better unnotched tensile strength and notched strength than pre‐thermal BFPLA specimens after they have been subjected to 100 TC ranging from −20 to 55°C. Thermal aging significantly influenced notch sensitivity, emphasizing its consideration in evaluating notch performance. This research provides a significant contribution to our current understanding of the effects of thermal aging on sustainable composites, enabling their informed application in a variety of industries and the results highlight their promising potential, in particular BFPBS, as strong alternative for medium load applications.Highlights Evaluated thermal aging effects on basalt fiber (BF) composites, revealing improved properties in BF/PBS composites after thermal cycles. Established quantitative link between mechanical behavior and thermal cycling using varying waterjet pressure values. Basalt fibers enhanced crystallinity and thermal stability of PLA and PBS polymers, showing promise for sustainable composites. Notch sensitivity impacted by thermal aging, underlining the importance of considering these effects in notch performance evaluation. BF/PBS composites demonstrated potential as robust alternatives for indoor products and sports equipment.

Replacing Needle Injection by a Novel Waterjet Technology Grants Improved Muscle Cell Delivery in Target Tissues

Current regimen to treat patients suffering from stress urinary incontinence often seems not to yield satisfactory improvement or may come with severe side effects. To overcome these hurdles, preclinical studies and clinical feasibility studies explored the potential of cell therapies successfully and raised high hopes for better outcome. However, other studies were rather disappointing. We therefore developed a novel cell injection technology to deliver viable cells in the urethral sphincter complex by waterjet instead of using injection needles. We hypothesized that the risk of tissue injury and loss of cells could be reduced by a needle-free injection technology. Muscle-derived cells were obtained from young male piglets and characterized. Upon expansion and fluorescent labeling, cells were injected into cadaveric tissue samples by either waterjet or injection needle. In other experiments, labeled cells were injected by waterjet in the urethra of living pigs and incubated for up to 7 days of follow-up. The analyses documented that the cells injected by waterjet in vitro were viable and proliferated well. Upon injection in live animals, cells appeared undamaged, showed defined cellular somata with distinct nuclei, and contained intact chromosomal DNA. Most importantly, by in vivo waterjet injections, a significantly wider cell distribution was observed when compared with needle injections (P < .05, n ≥ 12 samples). The success rates of waterjet cell application in living animals were significantly higher (≥95%, n = 24) when compared with needle injections, and the injection depth of cells in the urethra could be adapted to the need by adjusting waterjet pressures. We conclude that the novel waterjet technology injects viable muscle cells in tissues at distinct and predetermined depth depending on the injection pressure employed. After waterjet injection, loss of cells by full penetration or injury of the tissue targeted was reduced significantly in comparison with our previous studies employing needle injections.

Experimental investigations on the surface characteristics of abrasive waterjet-milled pockets in aluminium 6061-T6 alloy

ABSTRACT Abrasive waterjet (AWJ) milling is suitable for generating pockets in difficult-to-machine ductile materials as the material removal is through local erosion with the exertion of minimal forces. However, the surface generated is non-uniform. The surface quality characterisation based on 2D profile parameters is insufficient to characterise the whole-milled surface. In this work, a region-wise surface characterisation approach is proposed and validated on Al6061-T6 material. The varying depth at jet start/stop (region 1), and jet traverse direction change (region 2) are qualitatively analysed. Following this, relatively flat central surface (region 3) is quantitatively characterised by 2D/3D surface roughness and waviness parameters. From the qualitative analysis, the mean depth at region 1 and region 2 is observed higher than the mean depth at region 3. The quantitative analysis at region 3 reveals that the surface quality improved in terms of surface waviness by ten times at lower waterjet pressures (P) and by two times at higher jet traverse rates (vf ). The surface roughness improved by 2.5 times at lower P, and roughness parameters found less sensitive to vf . Finally, from the results, it is concluded that the 3D characterisation with surface waviness as parameter suits better for AWJ milled surfaces.

Fabrication of high aspect ratio free-standing structures using abrasive water jet micro-machining

The abrasive water jet micro-machining of high aspect ratio free-standing structures such as fins used in heat sinks was investigated. The aim was to fabricate the maximum number of fins per unit length with the highest aspect ratio into Al6061-T6, in order to maximize heat transfer potential. Adjacent straight channels at various offsets were machined using a micro-nozzle, thus leaving the free-standing structures in between. The effect of varying nozzle traverse speed, number of passes, water jet pressure, channel offset, and abrasive mass flow rate on the quality of the resulting free-standing structures was studied. Under some conditions, an undesirable ‘leveling’ phenomenon was found to occur, i.e. the tops of the free-standing structures eroded due to particle impacts at the periphery of the jet, and secondary slurry flow from within the channels between the structures. In general, conditions that led to a higher erosion rate (higher water jet pressures, lower nozzle traverse speeds, and higher abrasive mass flow rates) were found to minimize the leveling at a given offset, because the channels between the structures rapidly became deep, and secondary slurry flow was directed along the channel, rather than up the sidewalls. A threshold minimum offset to avoid this phenomenon was also determined. Contrary to previously reported results, it was found that the jet had ample energy to erode the target material even at effective stand-off distances (distance between nozzle and channel bottom) greater than 10 mm, provided that sufficiently large abrasive particles are used. With these factors in mind, it was demonstrated that high-quality free-standing structures with aspect ratios of more than 40 could be fabricated.

Mechanical and comfort properties of hydroentangled nonwovens from comber noil

Cotton is one of the most important commodity fibres and is widely employed in apparels. At present, the share of natural fibres in production of nonwoven fabrics is low and are used in opt applications. The cotton fibre is conventionally converted into woven and knitted fabrics by short staple spinning methods. The comber noil is short fibre waste produced when cotton yarns are combed. The aims of the current study were to employ comber noil for the preparation of hydroentangled cotton nonwovens at varying water jet pressures and conveyor speeds. The effect of these parameters was studied with respect to mechanical and comfort properties of the prepared fabrics. The results showed that these variables can help to manufacture fibrous assemblies with engineered properties, according to required application area.

Study and evaluation of abrasive water jet cutting performance on AA5083-H32 aluminum alloy by varying the jet impingement angles with different abrasive mesh sizes

ABSTRACTThis article describes the experimental investigation of abrasive water jet (AWJ) cutting on AA5083-H32 aluminum alloy. In this study, the influence of varying the jet impingement angles and abrasive mesh sizes with different water jet pressures, on the output parameters for the AWJ cutting of the aluminum alloy, was analyzed. The experimental results found that the output parameters, namely, the depth of penetration, top kerf width, kerf taper ratio, surface roughness, and abrasive contaminations, were strongly influenced by the combined effect of oblique jet impingement angles and abrasive mesh sizes on AWJ. Also, it is noticed that oblique jet impingement angles have more influence on the output cutting responses than the normal jet impingement angle, and consequently, each abrasive mesh size has an influence on the different output responses for the AWJ cutting of AA5083-H32. Scanning electron microscope and microhardness tester were used to examine the different cutting regions of the kerf wall surfaces. The Energy-dispersive X-ray spectroscopy analysis was used to confirm the amount of silicon particles embedded in the AWJ cut surfaces. The adequacy checking of the experimental data for the AWJ cutting performance models has been analyzed through the residual plots using the statistical software.

Surface integrity studies on abrasive water jet cutting of AISI D2 steel

ABSTRACTThis article investigates the 3D surface topography and 2D roughness profiles, and micrographs were analyzed in the abrasive water jet (AWJ) cutting of AISI D2 steel kerf wall cut surfaces by varying water jet pressures and jet impact angles. In 3D surface topography, roughness parameters such as Sq, Ssk, Sp, Sv, Sku, Sz, and Sa were improved by various jet impact angles with different water jet pressures. However, the roughness parameters Ssk and Sku strongly depend on the water jet pressure and jet impact angle. This is confirmed by kerf wall cut profile structures. Fine irregularities of peaks and valleys are found on the AWJ cut surfaces, as evident from 2D roughness profiles. The scanning electron microscope micrographs confirm the production of an upper zone not very much damaged and a lower striation free bottom zone, by using the jet impact angle of 70° with a water jet pressure of 200 MPa. Finally, the results indicate a jet impact angle of 70° maintaining the surface integrity of D2 steel better than normal jet impact angle of 90°. The results are useful in mating applications subjected to wear and friction. This has resulted in enhancement of the functionality of the AWJ machined D2 steel components.

Development of hydroentangled nonwoven fabrics for the protective garments

The aim of this research was to establish the optimum processing conditions for producing hydroentangled nonwoven fabrics best suited for application in disposable and protective wear, such as surgical gowns, drapes and laboratory coats. Carded and cross-lapped webs, from greige cotton, viscose and polyester fibres of three basic weights, were hydroentangled, at three different waterjet pressures on a Fleissner’s Aquajet hydroentanglement machine. An antibacterial agent and a fluorochemical water repellent finish were applied in one bath using the pad-dry-cure technique to impart both antibacterial and water repellent properties to the fabrics. The standard spray ratings, tensile strength and extension at break for three treated and untreated fabrics were evaluated. The spray ratings for the treated fabrics ranged from 80% to 90% against zero for the untreated fabrics while the tensile strengths in both the machine and cross-machine directions of treated fabrics were greater than that for the untreated fabrics, the reverse being true for the extension at break. Contact angles for all treated fabrics exceeded 90° which indicate good resistance to wetting. The finishing treatment decreased the mean pore size of all fabrics and increase in waterjet pressure and fabric weight decreased the air and water permeability. In this study, it was observed that low weight fabrics of 80 g/m2 hydroentangled at low waterjet pressure of 60 bars were suitable for use due to their higher air and water vapour permeability as well as higher pore size distribution. These fabrics meet the requirements for surgical gowns, drapes, nurses’ uniforms and laboratory coats.

Waterjet cutting of periprosthetic interface tissue in loosened hip prostheses: An in vitro feasibility study

Waterjet cutting technology is considered a promising technology to be used for minimally invasive removal of interface tissue surrounding aseptically loose hip prostheses. The goal of this study was to investigate the feasibility of waterjet cutting of interface tissue membrane. Waterjets with 0.2 mm and 0.6 mm diameter, a stand-off distance of 5 mm, and a traverse speed of 0.5 mm/s were used to cut interface tissue samples in half. The water flow through the nozzle was controlled by means of a valve. By changing the flow, the resulting waterjet pressure was regulated. Tissue sample thickness and the required waterjet pressures were measured. Mean thickness of the samples tested within the 0.2 mm nozzle group was 2.3 mm (SD 0.7 mm) and within the 0.6 mm nozzle group 2.6 mm (SD 0.9 mm). The required waterjet pressure to cut samples was between 10 and 12 MPa for the 0.2 mm nozzle and between 5 and 10 MPa for the 0.6 mm nozzle. Cutting bone or bone cement requires about 3 times higher waterjet pressure (30–50 MPa, depending on used nozzle diameter) and therefore we consider waterjet cutting as a safe technique to be used for minimally invasive interface tissue removal.

Optimization of energy usage in the hydroentanglement process

The hydroentanglement process is highly energy intensive compared to other methods of manufacturing nonwoven fabrics. This paper presents an exploratory study on optimizing the usage of hydroentanglement energy so as to lower the processing cost. The experiments were based on a Box–Behnken experimental design (BBD) and multivariate linear regression analysis to model the tensile strength as response to variables. Three variables were selected, namely fabric area weight (150–400 g/m2), machine speed (5–15 m/min) and waterjet pressure (40–200 bars). These parameters were employed in two sets of experiments to achieve maximum tensile strength of viscose nonwoven fabrics. The first experiment was conducted using higher waterjet pressures of 100, 150 and 200 bars, which were proved to have exceeded the optimum levels. The second experiment was conducted at relatively lower waterjet pressures of 40, 60 and 80 bars. The results on tensile strength were analyzed using the SYSTAT 10 software package and response surface plots were prepared. The linear, quadratic and interactive effects of the main variables were shown to be significant. Interactions amongst the variables were found to have either a synergistic (positive) or offsetting (negative) relationship with the fabric tensile strength. The interactions involving machine speed were predominantly offsetting. The 400 g/m2 area weight fabric produced at 80 bars of waterjet pressure achieved a fabric tensile strength of 222 cN, which compared favorably with that of 232 cN obtained at 200 bars of waterjet pressure. In this exploratory study using BBD, linear, quadratic and interactive effects were observed to be significant and the usage of hydroentanglement energy was successfully optimized. This indicates the possibility of achieving high fabric strength but at lower waterjet pressures; in other words, by employing low hydroentanglement energy and thereby minimizing the processing cost.

Abrasive Waterjet Cutting of Aluminum Alloys: Workpiece Surface Roughness

Abrasive waterjet machining is one of the non-traditional methods of the recent years which found itself a wide area of application in the industry for machining of different materials. In this paper, the surface roughness of 6061-T6 and 7075-T6 aluminum alloys are being cut with abrasive waterjet is examined experimentally. The experiments were conducted with different waterjet pressures and traverse speeds. It has been found that the surface roughness obtained by cutting material with high mechanical properties is better than that of obtained by cutting material with inferior mechanical properties.

Studies on waterjet impact forces in the hydroentanglement process

In the hydroentanglement process, high velocity multiple waterjets are generated through the nozzles before impinging on the hydroentangling belt or fibre-web and exert an impact force. In this study, a technique to measure important characteristics of the waterjets, namely, the coefficient of velocity, Cv, and coefficient of discharge, Cd, is proposed. The technique offers a simple and practical method to determine the energy transfer efficiency from the manifold to the waterjets. The measured Cv and Cd values were observed to decrease with an increase in waterjet pressure, which implied higher energy losses at higher waterjet pressures. These results were then used in the next experiment to measure the waterjet impact force. The waterjet impact force was measured using a Tensiometer-R2000 fixed on a vibration-free stand at different waterjet pressures, varied from 30 to 120 bar. It was observed that the waterjet impact forces were equal across the width of the machine at a given pressure, but increased proportionally with the increase in the waterjet pressure. When the empirical relation was fitted between experimental and theoretical values of waterjet impact force, it was found that theoretical values were overestimated.

Waterjet Dissection of Peripheral Nerves: An Experimental Study of the Sciatic Nerve of Rats

Although waterjet dissection has been well evaluated in intracranial pathologies, little is known of its qualities in peripheral nerve surgery. Theoretically, the precise dissection qualities could support the separation of nerves from adjacent tissues and improve the preservation of nerve integrity in peripheral nerve surgery. To evaluate the potential of the new waterjet dissector in peripheral nerve surgery. Waterjet dissection with pressures of 20 to 80 bar was applied on the sciatic nerves of 101 rats. The effect of waterjet dissection on the sciatic nerve was evaluated by clinical tests, neurophysiological examinations, and histopathological studies up to 12 weeks after surgery. With waterjet pressures up to 30 bar, the sciatic nerve was preserved in its integrity in all cases. Functional damaging was observed at pressures of 40 bar and higher. However, all but 1 rat in the 80 bar subgroup showed complete functional regeneration at 12 weeks after surgery. Histopathologically, small water bubbles were observed around the nerves. At 40 bar and higher, the sciatic nerves showed signs of direct nerve injury. However, all these animals showed nerve regeneration after 12 weeks, as demonstrated by histological studies. Sciatic nerves were preserved functionally and morphologically at pressures up to 30 bar. Between 40 and 80 bar, reliable functional and morphological nerve regeneration occurred. Waterjet pressures up to 30 bar might be applied safely under clinical conditions. This technique might be well suited to separate intact peripheral nerves from adjacent tumor or scar tissue. Further studies will have to show the clinical relevance of these dissection qualities.

The influence of water jet pressure settings on the structure and absorbency of spunlace nonwoven

Nowadays, the use of nonwovens as absorbent products is increasing. One of the most important methods for the nonwoven production is spunlace. This research evaluates the effect of spunlace nonwoven structures in wicking, water retention, water vapor permeability and porosity structural parameter of nonwoven. Carded webs from polyester fibers and viscous fibers of four different basis weights (35, 40, 45, and 50 g/m2) were hydroentangled using three different water jet pressures (50, 60, and 70 bar). To study the effect of these variables on the structure of nonwovens and absorbency related properties, sample’s characteristics such as thickness and mass density were measured. An electrical resistance technique was used to study the liquid penetration into nonwovens. The results showed that with increasing water jet pressure, mass density increased and other parameters like thickness, water retention, water vapor permeability and capillary pore size decreased. Also, it was observed with increasing basis weight, the sample thickness increased. On the other hand, with increasing weight, the amount of water retention, water vapor permeability and porosity structural parameter of nonwoven were reduced. The wicking characteristic of nonwovens using the least jet pressure and weight was the best of all the samples.

Waterjet dissection in pediatric cranioplasty

Waterjet dissection has been shown to separate tissues of different resistance, with preservation of blood vessels. In cranioplasty, separation of subcutaneous tissue and dura mater is often difficult to achieve because the various tissue layers strongly adhere to each other after decompressive craniotomy. In the present study, the potential advantages and drawbacks of the waterjet technique in cranioplasty after craniectomy and duraplasty are addressed. The waterjet effect on fresh human cadaveric dura mater specimens as well as on several dural repair patches was tested in vitro under standardized conditions, with waterjet pressures up to 80 bar. Subsequently, 8 pediatric patients (5 boys, 3 girls; mean age 9.9 years, range 1.2-16.7 years) who had been subjected to decompressive craniectomy (7 with duraplasty including bovine pericardium as a dural substitute, 1 without duraplasty in congenital craniosynostosis) underwent waterjet cranioplasty. The waterjet was used to separate the galea and the dura mater. The technique was applied tangentially between the dura and the galea, with different pressure levels up to 50 bar. In vitro, fresh cadaveric human dura mater as well as 2 different dural repair substitutes showed a very high resistance to waterjet dissection up to 80 bar. The human dura and the various substitutes were dissected only after long-lasting exposure to the waterjet. Human dura was perforated at pressures of 60 bar and higher. Bovine pericardium dural substitute was perforated at pressures of 55 bar and higher. Artificial nonabsorbable polyesterurethane dural substitute was dissected at pressures of 60 bar and higher. In the clinical setting, the waterjet was able to separate galea and dura with minimal bleeding. No blood transfusion was required. Dissection of scarred tissue was possible by a waterjet of 40 bar pressure. Tissue layers were stretched and separated by the waterjet dissection, and a very reliable hemostasis resulted. This resulted in an effective reduction of bleeding, with < 60 ml blood loss in 7 of the 8 cases. Neither a dural tear nor a perforation of any duraplasty occurred during operative preparation. There were no operative or postoperative complications. The experimental and clinical data show that waterjet separation of dura mater, dural substitute, and galea can be performed with a high level of safety to avoid dural tears. The waterjet dissection stretches tissue layers, which results in a reliable hemostasis effect. This potentially results in an effective reduction of surgical blood loss, which should be the focus of further studies.

Optimization of Parameters in Hydroentanglement Process

Hydroentanglement is a versatile and relatively little explored method of bonding the fibrous web using high-pressure water jets. These nonwoven structures have an extensive range of applications–for example, wipes, carpet backing, filters, sanitary, medical dressings, and composites. Such applications require certain functional characteristics in hydroentangled structures, besides basic properties, which are required to be engineered by judicious optimization of the hydroentanglement process. In this study, a number of hydroentangled structures have been produced based on Taguchi's experimental design technique by varying the process parameters: namely, feed rate and water jet pressures. The simultaneous effect of more than one parameter has been investigated on the dimensional and mechanical properties of hydroentangled fabrics. These process parameters are then empirically related with the fabric properties using the multiple regression technique. The influence of jet pressure was found to be significant on the fiber orientation characteristics of the hydroentangled fabrics.

Improving the cut surface qualities using different controlled nozzle oscillation techniques

One of the principle deficiencies of the abrasive water jet (AWJ) cutting process is wavy striations on the generated cut surface in relatively thick workpieces. A desirable surface finish can be obtained only when the thickness of the workpiece is less than the depth of the smooth zone. Due to the limitation of the waterjet pressures from the current pumping technology, minimisation of striations without the sacrifice of the cutting speed and so increasing the smooth zone depth would constitute a marked improvement in the AWJ machining. In this study, different nozzle oscillation cutting techniques were developed to optimise the AWJ machining process. A comparative study was conducted using different surface texture parameters among straight cutting and different oscillation cutting methods under the same input cutting parameters. Detailed analyses of the cutting results indicate that a significant enhancement in the cut surface quality was obtained by using the controlled cutting nozzle oscillation techniques.

Effect of Feed Rate During Comminution of Coal by High Energy Waterjet

Abstract High pressure waterjets attack, fragment and comminute coal. The purpose of this research is to determine the effect of selected waterjet parameters on the specific energy required to create particles less than 75 μm in size. The selected parameters are waterjet pressure, nozzle diameter, relative velocity between moving coal sample and stationary waterjet nozzle and nozzle standoff distance, defined as the distance between nozzle and target. This information is necessary as a starting point for the design of coal comminution equipment based on waterjet technology. Over 980 individual specimens of bituminous coal from Moberly, Missouri USA, were subjected to controlled attack by waterjet. Trials were executed with waterjet pressures up to 100 MPa, and with nozzle standoff distances between 0.80- to 44.5 × 10−3 m. Nozzle diameters of 1.14-, 0.81 -, and 0.41 × 10−3 m were used, and coal sample feedrates varied up to 0.127ms−1 relative to a stationary nozzle. The most important parameter was found t...

Water Jet Cutting of Sedimentary Rock

Depth and specific energy of breakage values are used to determine the relative efficiencies of a continuous water jet cutting sandstone and limestone. Results of using jet action alone compared with results obtained when mechanical breakage is also used to remove rock indicate that the latter method is the more effective. Introduction In the past few years there bas been a rapidly growing interest in adapting new and unusual techniques to meet the problems of rock excavation, particularly in drilling and tunneling. In his particularly in drilling and tunneling. In his initial analysis of methods that had potential for solving drilling problems, Maurer listed 30 such techniques that might be used. On the basis of Maurer's work and of more recent analysis and experimentation, water jet erosion of rock has been found to hold promise as a means of rock removal in hard- and soft-rock tunneling, in coat mining, and in drilling. To date, investigation of this technique has been generally confined to determining the factors that control the cutting rate of the jet through laboratory experiments on prepared samples of rock. Such testing has been related only indirectly to the practical problem of rock excavation inasmuch as the practical problem of rock excavation inasmuch as the rock likely to be removed in situ will be under ground stress and will be unlike the quasi-homogeneous, isotropic, nonfractured sample used in the laboratory. Nevertheless, the results of such experimentation indicate the potential water jet pressures that will be required in the field system and the level of power consumption. An advantage of water jets in such a system is that in some circumstances the water jet acts as fluid wedge so that where fractured rock or rocks with weaknesses and joints are attacked the performance figures will be higher than those attained performance figures will be higher than those attained in the laboratory. Two separate concepts may be envisaged in designing a tool for water jet drilling. In the first, an arrangement of water jet nozzles may be rotated so that the resulting jets remove all the rock at the face of the cut by first cutting slots in the rock and then removing the intervening ribs by water jet action alone. In the second concept the water jet may be used to cut slots, leaving ribs of rock that are then removed by mechanical means - for example by roller cutters rotating either within the slot to wedge out the ribs, or along the center of the intervening rib. To determine the relative efficiency of each of these techniques, calculations were made of the specific energies of cutting, relating the energy level required to remove a given volume of rock under various cutting conditions. Experiments were carried out on samples of rock, using a water jet delivered from a high-pressure pump through a nozzle 0.023 in. in diameter. Rock Cutting by Water let To determine the distance between adjacent cuts at which the water jet would not only cut a slot for itself as it traversed, but also remove the intervening rock rib between slots. samples of rock were placed on the horizontal carriage of a lathe and linearly traversed under the water jet nozzle to cut a straight slot. Two types of rock were used in this series of tests, Berea sandstone and Indiana limestone. JPT P. 797