Views: 235 Author: SGA Garnet Team Publish Time: 2022-11-11 Origin: SGA Waterjet
In the fields of industrial manufacturing and machining, traditional cutting processes rely on tools harder than the workpiece to remove excess material via mechanical force; alternatively, separation is achieved by using high-temperature heat sources to locally melt the material.
Compared to traditional machining technologies, ultra-high-pressure waterjet (abrasive waterjet) machining offers significant advantages, such as powerful cutting capabilities, low processing costs, and environmental friendliness. The process generates no significant amounts of waste slag or toxic gases, making it a truly versatile and efficient cold-cutting process.
Abrasive waterjet cutting utilizes the high-speed erosive action of a "water plus garnet abrasive" mixture. This not only eliminates the limitations inherent in traditional cutting—such as tool wear and the requirement that the tool must be harder than the workpiece—but also, as a purely cold-cutting process, completely avoids issues associated with thermal cutting, such as edge charring, discoloration, thermal deformation, and the formation of a heat-affected zone (HAZ).
The principle of abrasive waterjet cutting involves pressurizing a water stream to an ultra-high level, thereby imparting immense kinetic energy to the flow. When garnet abrasive is introduced into this high-speed water stream, the combination of water and abrasive creates a powerful erosive force capable of cutting hard materials such as ceramics, stone, glass, metals, and alloys.
Because waterjet systems involve ultra-high-pressure water streams, abrasive delivery, CNC motion platforms, lifting operations, and waste abrasive handling, improper operation can not only compromise cutting precision but also pose serious risks of personal injury and equipment damage.
The following information serves as a reference for safety checks to be performed before, during, and after the operation and maintenance of high-pressure abrasive waterjet systems.
Before entering the waterjet operating area, operators must wear PPE appropriate for the site's risk level:
● Impact-resistant safety goggles or face shields (compliance with ANSI Z87.1 or EN 166 standards is recommended);
● Hearing protection, such as earplugs or earmuffs. Mandatory use is required if on-site noise exposure reaches an 8-hour TWA of 85 dBA or meets company EHS requirements;
● Cut-resistant gloves for handling sharp workpieces such as metal, glass, or stone;
● Slip-resistant safety shoes to prevent slips caused by standing water, abrasive media, or cutting debris;
● Appropriate respiratory protection based on dust conditions when handling dry garnet abrasive or cleaning up spent abrasive.
PPE is not a substitute for safe operating practices. Risks associated with high-pressure water jets, abrasive streams, and moving equipment parts must be controlled through shutdown, isolation, depressurization, and the use of protective guards.
Before startup, inspect the intensifier pump, ultra-high-pressure (UHP) piping, fittings, valve assemblies, and cutting head for leaks, cracks, deformation, or abnormal wear.
Never touch or approach a suspected leak point with your hands. UHP micro-jets can penetrate the skin and cause severe injury. If a leak is detected, immediately shut down the system, depressurize it, and have qualified personnel inspect and address the issue.
The cutting stability of an abrasive waterjet system depends heavily on the condition of abrasive delivery. Before startup, inspect the abrasive hopper, abrasive valve, delivery hose, and mixing chamber:
● Confirm that the garnet abrasive is dry and free of clumps;
● Check the abrasive hopper for moisture or condensation;
● Ensure the delivery hose is clear to prevent clogs caused by damp abrasive;
● Verify that the abrasive flow setting matches the current material and cutting program;
● Confirm the use of "Waterjet Grade" garnet rather than standard sandblasting abrasive.
UHP waterjet systems are sensitive to inlet water quality. Hard water, impurities, and abnormal temperatures can affect the service life of seals, check valves, intensifier plungers, and high-pressure piping.
Before startup, check the following in accordance with the manufacturer's specifications:
● Inlet water filtration status;
● Water quality parameters (for softened or treated water);
● Water temperature (ensure it is within the equipment's allowable range);
● Proper operation of the cooling system or chiller;
● Water pressure and flow rate (ensure they meet intensifier pump requirements).
| 1. Maintain a Safe Distance | During equipment operation and cutting tasks, operators and unauthorized personnel must maintain a safe distance from the cutting platform, cutting head, and moving mechanisms. Do not extend hands, tools, or any part of the body into the cutting zone. |
| 2. Secure Small Workpieces | When cutting workpieces that are small, lightweight, or easily displaced by the water jet, measures such as clamping, holding down, or using auxiliary fixtures must be taken to prevent the workpiece from shifting during the cutting process. |
| 3. Ensure Plate Flatness | When loading the workpiece, ensure it is placed flat and supported stably. Warped or raised plates may strike the cutting head, mixing tube, or focusing tube, leading to equipment damage or safety accidents. |
| 4. No Manual Correction During Operation | If a workpiece is observed shifting due to the water jet during cutting, it is strictly prohibited to attempt to force it back into position manually or with tools while the equipment is running. Immediately pause the program, shut off the high-pressure water, and wait for the cutting head to stop and for safety to be confirmed before addressing the issue. |
| 5. Adjust Pressure and Cutting Parameters | Different materials require specific settings for cutting pressure, abrasive flow rate, cutting speed, piercing method, and nozzle standoff distance. Materials such as glass, ceramics, composites, and cemented carbides require particularly careful setting of piercing and cutting parameters to avoid edge chipping, cracking, or cutting failure. |
| 6. Monitor Equipment Status | Operators must monitor the control cabinet, pressure gauges, CNC alarm messages, abrasive levels, and cutting sounds in real time. If abnormal pressure, abrasive flow interruption, nozzle clogging, deviation of the cutting line, or equipment alarms are detected, the machine must be stopped immediately for inspection. |
| 7. Lifting and Loading/Unloading Plates | When using overhead cranes, mobile cranes, or forklifts to load or unload heavy plates, verify the lifting gear, lifting points, and lifting path. Strictly avoid collisions with the waterjet machine bed, guide rails, cutting head, high-pressure piping, or control cables. |
Before retrieving parts, replacing cutting head components, inspecting the nozzle, removing the mixing tube, or clearing a clog, the high-pressure water must be shut off and the depressurization procedure performed. Manual work may only commence after it is confirmed that all residual system pressure has been fully released. Adhere to lockout/tagout procedures during maintenance. Do not disassemble high-pressure components until power has been disconnected, the system isolated, and pressure relieved.
Regularly clear accumulated waste abrasive and cutting residue from the bottom of the water tank. Excessive accumulation of waste abrasive can compromise material support—causing the workpiece to warp or lift—and may interfere with moving equipment parts. If the material being cut contains heavy metals, coatings, composites, or other contaminants, dispose of waste abrasive and sludge in accordance with local environmental regulations.
After processing, promptly clear the workpiece, scrap material, and work area; shut down the power, water, and air supplies as required. Immediately press the Emergency Stop (E-stop) button and halt operations to investigate if any of the following occur:
| Trigger | Observed Condition |
|---|---|
| Pressure present but no water flow | The intensifier pump shows normal pressure, but no high-pressure water exits the cutting head. |
| Severe pressure fluctuation | Water flow from the cutting head becomes intermittent, or the pressure gauge shows noticeable pulsation or abnormal oscillation. |
| High-pressure component leakage | Cracks, deformation, leakage, or spraying appear from UHP lines, fittings, valve assemblies, or the cutting head. |
| Abrasive delivery abnormality | Abrasive flow is interrupted, clogged, unstable, or cutting performance suddenly drops. |
| Workpiece displacement or plate lifting | The workpiece moves, warps, lifts, or creates a collision risk during cutting. |
| Equipment alarm or abnormal sound | The CNC system, intensifier pump, cooling system, or abrasive valve reports alarms, abnormal sounds, or unusual vibration. |
For more information on workplace safety controls related to waterjet operation, operators and EHS managers may refer to the following OSHA resources:
Noise Exposure | Eye and Face Protection | Control of Hazardous Energy
