Waterjet cutting works by converting hydraulic pressure into jet velocity and then transferring that kinetic energy to the workpiece. Water is pressurized by a high-pressure pump and delivered through high-pressure tubing to the cutting head. Inside the cutting head, a precision orifice converts the pressure energy into a narrow, fast-moving water stream.
For soft materials, the concentrated water stream can perform the cutting directly. For stone, metal, ceramic, glass and other hard materials, garnet abrasive is introduced into a mixing chamber. The water stream accelerates the abrasive particles through a focusing tube, producing a coherent abrasive jet that removes material by high-speed impact, micro-cutting and erosion.
The process can therefore be summarized as:
Filtered water → high-pressure pump → high-pressure tubing → precision orifice → high-speed water jet → abrasive entrainment when required → mixing and acceleration → material erosion → CNC-controlled cutting path.
Waterjet cutting is commonly described as a cold cutting process because it does not rely on a flame, plasma arc or concentrated thermal beam to melt the workpiece. Heat generated locally by friction is carried away by the water, greatly reducing the risk of a conventional heat-affected zone.
The cutting result is not created by pressure alone. It is produced by a connected energy-transfer process. A loss or instability at any stage can reduce cutting speed, increase edge taper or create an inconsistent kerf.
The process begins with a stable water supply. Incoming water normally passes through filtration and, where required, additional treatment before entering the high-pressure pump.
Water quality affects seals, valves, orifices and other high-pressure components. Suspended particles can damage sealing surfaces or obstruct a small orifice. Excessive mineral content may form deposits, while unsuitable water chemistry can shorten component life.
The water-treatment requirement should therefore be determined from an actual water analysis rather than from appearance alone. Important factors include suspended solids, hardness, dissolved minerals, pH and supply pressure.
Clean and consistent inlet water does not perform the cutting by itself, but it protects the components responsible for generating and maintaining the cutting jet.
The high-pressure pump supplies the energy required for cutting. Industrial systems may use an intensifier pump, a direct-drive pump or another suitable high-pressure design.
In a hydraulic intensifier, hydraulic pressure acts on a piston with a relatively large surface area. The piston drives a smaller water plunger, multiplying the pressure applied to the cutting water. Check valves control the inlet and outlet flow as the intensifier cycles.
A direct-drive system uses a crankshaft and plungers to pressurize the water mechanically. Although the mechanical arrangements differ, both designs must deliver the required combination of pressure and water flow.
A pressure reading should not be evaluated in isolation. The cutting head needs stable energy during the entire toolpath. Rapid pressure fluctuation, worn seals, leaking check valves, restricted inlet water or abnormal pump cycling can produce uneven cutting even when the displayed peak pressure appears sufficient.
Yongtao industrial configurations are commonly selected within an approximate working-pressure range of 380–420 MPa, depending on the pump, cutting requirement and machine configuration. The correct operating value must follow the approved pump specification rather than a universal pressure setting.
Pressurized water travels from the pump to the cutting head through high-pressure tubing, fittings, swivels and valves. These components must contain the pressure while allowing the machine axes and cutting head to move safely.
Every connection in this circuit is part of the energy path. Leakage, damaged tubing, loose fittings, internal valve wear or an incorrect installation radius can affect performance and safety.
High-pressure components must never be treated like ordinary plumbing. Inspection, installation and replacement should follow the component manufacturer’s procedures. Operators should depressurize the system completely before maintenance and should never attempt to locate a high-pressure leak with an unprotected hand.
A stable high-pressure circuit preserves the pump output until the water reaches the orifice.
The precision orifice is one of the most important components in the cutting head. It contains a very small opening, commonly made from a wear-resistant material such as sapphire, ruby or diamond.
As pressurized water passes through this opening, pressure energy is converted into kinetic energy. The result is a fine, high-velocity water jet.
The orifice diameter influences both water flow and the energy available to accelerate abrasive. A larger orifice generally requires more pump flow. An orifice that does not match the pump capacity may prevent the system from maintaining the intended working pressure.
Orifice condition is equally important. Wear, contamination, chipping or incorrect seating can cause the jet to become unstable or misaligned. Instead of entering the center of the mixing tube, the water stream may strike its internal wall, accelerating wear and reducing abrasive transfer efficiency.
This is why pressure, flow, orifice size and pump capacity must be evaluated as one system.
In abrasive cutting, the high-speed water jet enters a mixing chamber before passing through the focusing tube. Its movement through the chamber creates a low-pressure region that draws metered abrasive into the cutting head.
The abrasive is not normally pumped through the high-pressure water circuit. It is stored in a hopper or abrasive-delivery system and transported through a feed hose to the cutting head. The vacuum created by the water jet draws the abrasive into the mixing chamber.
Garnet is widely used because its hardness, density, fracture behavior and availability make it suitable for industrial abrasive cutting. However, cutting performance also depends on mesh size, cleanliness, dryness and flow consistency.
Moisture, contamination, damaged feed tubing or an unstable metering system may cause the abrasive flow to pulse or stop. This can leave sections of the toolpath incompletely cut even when water pressure remains normal.
After entering the mixing chamber, abrasive particles interact with the high-speed water stream. Energy is transferred from the water to the abrasive as the mixture travels through the focusing or mixing tube.
The focusing tube aligns the mixture and helps form a coherent abrasive jet. Its internal diameter, length, material, alignment and wear condition all affect the efficiency of this stage.
The abrasive particles, rather than water pressure alone, perform much of the material removal when cutting hard materials. If the orifice and focusing tube are not concentrically aligned, the jet can strike the wall of the tube. This reduces useful energy, enlarges the jet and causes uneven wear.
As a focusing tube wears, the effective jet diameter and cutting behavior can change. Possible symptoms include a wider kerf, lower cutting efficiency, rougher edges, increased taper or difficulty maintaining dimensional consistency.
When the jet reaches the workpiece, its kinetic energy is concentrated over a small area. The jet first penetrates the surface and then removes material continuously as the cutting head follows the programmed path.
In abrasive cutting, high-speed garnet particles strike the material and produce repeated microscopic fractures, deformation and erosion. The loosened material is carried downward into the catcher tank by the water and spent abrasive.
The opening left by the jet is called the kerf. Kerf width and geometry are affected by the orifice and focusing-tube combination, material type, thickness, pressure, abrasive flow, traverse speed, stand-off distance and component condition.
The jet loses energy as it passes through the material. It can therefore lag behind the cutting head, especially when cutting thick material too quickly. This behavior is called jet lag and is one reason the bottom of a cut may not follow the top path exactly.
Pure-water cutting uses the concentrated water jet without adding abrasive. It is best suited to relatively soft or easily separated materials, depending on the application.
Typical examples may include:
Rubber
Foam
Textiles
Paper products
Soft plastics
Insulation materials
Certain food products and packaging materials
Because no garnet is added, the cutting head does not require the same abrasive mixing process used for hard materials. The water jet itself penetrates and separates the material through concentrated impact and erosion.
Pure-water cutting can produce a narrow kerf and avoids abrasive contamination. However, it should not be selected simply to reduce abrasive cost. Material structure, thickness, moisture sensitivity, required edge quality and production speed must all be considered.
Abrasive waterjet cutting adds a controlled quantity of abrasive to the high-speed water stream. This changes the process from water-only separation into a more powerful erosion and micro-machining method.
The sequence is:
The pump supplies pressurized water.
The orifice produces a high-speed water jet.
The jet creates negative pressure in the mixing chamber.
Garnet enters through the abrasive feed port.
Water transfers energy to the abrasive particles.
The mixture is aligned and accelerated inside the focusing tube.
The abrasive jet strikes and removes the workpiece material.
This method is commonly used for stone, stainless steel, carbon steel, aluminum, copper, ceramic tile, sintered stone, quartz, non-tempered glass and many composite materials.
Abrasive flow should remain controlled rather than simply being maximized. Too little abrasive can reduce cutting capacity, while excessive abrasive may not be accelerated efficiently and can increase operating cost. The suitable setting depends on the pump output, orifice and mixing-tube combination, material, thickness and required cutting quality.
Cutting medium: High-speed water only
Primary removal mechanism: Water impact and erosion
Typical materials: Rubber, foam, textiles and other soft materials
Main advantage: Narrow cutting stream without abrasive contamination
Primary limitation: Insufficient cutting capacity for many dense or hard materials
Cutting medium: High-speed water, air and metered abrasive
Primary removal mechanism: Particle impact, micro-cutting and erosion
Typical materials: Stone, metal, ceramic, glass and composites
Main advantage: Cuts many thick, hard or heat-sensitive materials
Primary limitation: Requires abrasive control and creates spent abrasive that must be managed
Some cutting heads can be configured or converted between these two processes. Conversion time and procedure depend on the equipment design, so a universal conversion time should not be stated for every system.
Pressure and abrasive create the cutting power, but the CNC motion system determines where that power is applied.
The operator imports or creates a drawing, defines the cutting path and assigns process parameters. The controller then coordinates the machine axes to move the cutting head along straight lines, curves, holes and other programmed geometry.
The control software may adjust feed rate for corners, small radii and different quality requirements. Slower movement allows the jet to remove more material from a given section, while faster movement increases productivity but may produce more pronounced striation or jet lag.
On multi-axis systems, the cutting head can also tilt. Depending on the machine design and software, this capability may be used for bevel cutting or for compensating for natural kerf taper.
The CNC system does not correct every mechanical or process problem automatically. Accurate motion cannot compensate for unstable pressure, interrupted abrasive flow, a damaged orifice or an excessively worn focusing tube.
Waterjet cutting quality results from the interaction of several parameters rather than from a single pressure value.
Pressure affects jet velocity and available cutting energy. Higher pressure can increase particle acceleration and cutting capability when the pump, orifice and other components are correctly matched. However, operating beyond approved specifications increases risk and does not correct poor abrasive delivery or worn components.
Water flow helps determine how much hydraulic power reaches the cutting head. Flow is influenced by pump capacity, pressure and orifice size. A system must be able to maintain both the intended flow and stable pressure during cutting.
A stable abrasive feed supports consistent material removal. Interrupted, damp or excessive abrasive flow can cause incomplete penetration, rough sections and unnecessary operating cost.
These components must be correctly sized and concentrically aligned. An incorrect combination can reduce abrasive acceleration and shorten focusing-tube life.
A slow traverse normally produces a smoother cut but increases cycle time. Excessive speed can cause heavy striation, greater jet lag or failure to cut completely through the material.
Stand-off distance is the gap between the focusing tube and the workpiece. If the gap is unnecessarily large, the jet can spread and lose coherence before reaching the material. The suitable distance depends on the cutting-head design, material and piercing strategy.
Hardness alone does not determine the correct setting. Brittleness, internal structure, thickness, layering and sensitivity to piercing can all influence cutting behavior.
A direct high-energy pierce may damage brittle or laminated materials. Low-pressure piercing, dynamic piercing, circular piercing or starting from an external edge may be selected where appropriate.
Laser, plasma and flame-cutting processes concentrate thermal energy to melt or oxidize material. Waterjet cutting removes material mainly through mechanical erosion.
The water also absorbs and carries away much of the localized heat generated by impact and friction. As a result, the workpiece does not normally develop the conventional heat-affected zone associated with thermal cutting.
This characteristic can help preserve material properties near the cut and reduce heat-related discoloration, melting or distortion. It does not mean that every part will remain completely free from mechanical effects. Poor support, aggressive piercing or incorrect parameters may still cause chipping, delamination or local damage.
A useful way to diagnose cutting problems is to trace the energy path from the water supply to the workpiece.
Common symptoms include:
Incomplete penetration: Check pressure stability, traverse speed, abrasive flow, nozzle condition and material thickness.
Increasing kerf width: Inspect focusing-tube wear, stand-off distance and jet alignment.
Rough lower edge: Check traverse speed, jet lag, abrasive flow and remaining jet energy.
Intermittent uncut sections: Inspect abrasive bridging, moisture, feed-hose blockage and pressure fluctuation.
Premature focusing-tube wear: Check orifice alignment, mixing-chamber condition and abrasive quality.
Uneven taper: Review speed, stand-off distance, nozzle wear, head alignment and any taper-compensation setting.
Excessive chipping during piercing: Review the pierce method, pressure sequence, material support and entry location.
The visible cut is the final result of the entire system. Replacing one component or increasing pressure without tracing the full process can hide the actual cause.
Pressure is important, but it is not the only factor. Effective cutting also depends on water flow, orifice size, abrasive acceleration, focusing-tube condition, traverse speed and material characteristics.
Pure water can separate many soft materials. For hard materials, most material removal is performed by abrasive particles accelerated by the water jet.
Abrasive must receive sufficient energy from the water stream. Adding more than the cutting head can accelerate efficiently may increase consumption without producing a proportional improvement.
A displayed value does not show whether pressure is stable throughout the cutting cycle or whether energy is being lost at the orifice, abrasive system or focusing tube.
The absence of a conventional heat-affected zone is an important advantage, but the process still involves extremely high pressure, fast-moving abrasive and high-energy discharge. Correct guarding, training, depressurization and maintenance procedures remain essential.
When cutting performance changes, inspect the system in a logical order:
Confirm that the material, thickness and program settings match the job.
Observe working pressure during continuous cutting rather than checking only the idle value.
Verify that abrasive reaches the cutting head continuously and remains dry.
Inspect the orifice and focusing tube for wear, damage or misalignment.
Check the stand-off distance and cutting-head position.
Review traverse speed, piercing method and selected quality level.
Inspect the high-pressure circuit for leakage or abnormal cycling.
Compare the result with a known test program and verified material sample.
This sequence separates motion, pressure, abrasive and nozzle problems more effectively than changing several parameters at the same time.
The working principle of waterjet cutting is a controlled conversion of energy. The pump creates hydraulic pressure, the orifice converts that pressure into jet velocity, and the cutting head transfers the jet’s energy to either the workpiece or the abrasive particles.
Pure-water cutting uses the water stream directly to separate soft materials. Abrasive cutting uses the water stream to draw in and accelerate garnet, allowing the process to erode hard materials without relying on a thermal cutting source.
Stable results require every stage to work together: suitable inlet water, consistent pump output, safe pressure delivery, a correctly sized orifice, controlled abrasive flow, accurate nozzle alignment, suitable stand-off distance and coordinated CNC movement.
For readers who want to compare equipment after understanding the operating principle, Yongtao provides 3-axis and 5-axis waterjet configurations for different materials, cutting angles and production requirements.
High-pressure water passes through a small precision orifice, which converts pressure energy into a narrow, high-velocity stream. The stream removes material through concentrated impact and erosion. When cutting hard materials, the water accelerates garnet particles that perform most of the material removal.
A high-speed water stream creates negative pressure inside the mixing chamber and draws abrasive into the cutting head. The water transfers kinetic energy to the abrasive as both pass through the focusing tube. The accelerated abrasive particles then strike and erode the workpiece.
No. Cutting performance depends on both pressure and water flow, as well as orifice size, abrasive flow, focusing-tube condition, traverse speed, stand-off distance and material properties. A high pressure value cannot compensate for an unstable abrasive supply or worn nozzle components.
Pure-water cutting uses only a concentrated water stream and is generally selected for soft materials such as foam, rubber and textiles. Abrasive cutting adds garnet to the stream and is used for harder materials such as stone, metal, ceramic and non-tempered glass.
Garnet provides a practical combination of hardness, density, cutting ability and availability. Its particles can receive energy from the water stream and remove material through repeated high-speed impact. Mesh size, cleanliness, dryness and consistency affect cutting performance.
The jet loses energy and may lag behind the cutting head as it travels through the material. Excessive traverse speed, insufficient cutting energy, unstable abrasive flow or worn nozzle components can increase lower-edge striation and roughness.
Waterjet cutting does not normally produce the conventional heat-affected zone associated with laser, plasma or flame cutting because it removes material mechanically rather than melting it. Water also carries away much of the localized heat generated during the process.
Possible causes include excessive traverse speed, insufficient or unstable pressure, interrupted abrasive flow, a damaged orifice, a worn focusing tube, an incorrect nozzle combination or material thickness beyond the programmed setting.
A damaged or worn orifice can produce an unstable or misaligned water stream. This reduces efficient abrasive acceleration, increases focusing-tube wear and may cause a wider kerf, rougher edge or inconsistent cutting result.
An excessive distance allows the jet to spread before reaching the workpiece, reducing energy density and cutting accuracy. A very small or incorrect distance may also interfere with piercing or increase the risk of nozzle contact. The setting should follow the cutting-head design and application.
Some systems can be configured or converted for both processes, but the procedure depends on the cutting-head and abrasive-delivery design. Pure-water operation does not require abrasive, while abrasive cutting requires a mixing chamber, feed system and focusing tube suitable for the selected configuration.
Check the working pressure, abrasive delivery, orifice condition, focusing-tube wear, stand-off distance and traverse speed. If the problem occurs intermittently, also inspect abrasive moisture, feed-hose blockage, pump cycling and high-pressure leakage.
0086-18665475362
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Road 3, Wuzhuang Xiaofengtian Ind. Zone, Luocun Town, Nanhai Dist., Foshan, Guangdong, China
0086-18665475362 
[email protected]
Road 3, Wuzhuang Xiaofengtian Ind. Zone, Luocun Town, Nanhai Dist., Foshan, Guangdong, China 
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