Waterjet Cutting: First Days at the Machine
What a waterjet does, what the operator does, and what can hurt you on your first days at the machine.
Table of contents
A waterjet cuts with a thin, extremely high-pressure stream of water, usually with a fine abrasive sand added. It can cut steel, titanium, stone, glass, rubber, foam and food. Since it does not use heat, it will not warp a part or change its hardness. That makes it a favorite in aerospace shops, stone shops and job shops. The operator's job is a mix of setup, watching the cut and keeping a demanding machine running.
What You Will Be Able to Do
- Explain what a waterjet does.
- Describe an operator's day.
- Name the hazards that can hurt you on day one.
- Say what to do if the jet ever touches skin.
- Run a basic pre-start check with your trainer.
What the Work Looks Like
There are two ways to cut.
| Mode | How it works | Typical materials |
|---|---|---|
| Pure water | Water alone cuts soft material | Foam, rubber, gaskets, food |
| Abrasive | Garnet sand in the stream does the cutting | Metal, stone, glass, composites |
The main parts are the pump, which builds pressure; the cutting head, which forms the jet; and the tank, a large water bath under the work that catches the jet and the spent garnet.
An operator's day often goes like this: check the machine, load and secure the material, load the program, run a test cut, watch the job and check the parts. Between jobs, you might top up garnet, change worn parts in the head, clean the tank or service the pump. Waterjets are slower than lasers on thin steel, so you will spend a lot of time near a running machine.
What Will Hurt You on Day One
The Jet
Industrial waterjets typically run at about 60,000 to 90,000 psi. At that pressure, the stream can pierce skin and force water, grit and bacteria deep into the body. The wound can look tiny, yet the damage underneath can be severe.
Warning: If the jet ever touches your skin, treat it as a surgical emergency. Go to an emergency room right away, even if it looks small, and tell them it is a high-pressure injection injury. This is not a first-aid injury.
Keep every part of your body away from the jet. Do not put your hand under the head, even at low pressure.
High-Pressure Plumbing
The tubing and fittings carry the same pressure as the jet. A small leak can cut. Never touch a leak or check for one with your hand. Stop the pump, bleed off the pressure and report it. Only trained people should service high-pressure parts, using the lockout procedure.
Slippery Floors
Water, mist and garnet make the floor near the tank slick. This is one of the most common ways to get hurt. Wear non-slip boots, keep mats in place and mop often.
The Moving Head
The head and gantry can move without warning under program control. Keep clear of them, and keep your hands off the bed when the machine is in cycle.
Noise
Cutting thick material, or cutting with a low tank, is very loud. Wear hearing protection.
Lifting and Sharp Edges
Plate, stone and glass are heavy, and cut edges can be sharp. Use a hoist for heavy loads. Wet sheet can slip out of your hands.
Dust and Slurry
Stone and glass cutting can leave silica in the slurry. When it dries, the dust can be breathed in. Keep it wet, and follow your shop's dust rules. Used garnet is heavy, so use the right tools to remove it.
Electrical Hazards
Water and electricity are close together. Report any leak near a control cabinet or motor.
Your First Week
Your trainer will likely have you watch first. Ask to learn these before you run anything:
- Where the emergency stops are.
- How to start and stop the pump.
- How to confirm that pressure is at zero.
- How to load and clamp material.
- What the guards and interlocks do.
Learn your machine's maintenance schedule too. Waterjets wear out parts constantly, so good operators pay attention to small changes in sound, pressure and cut quality.
Your First Exercise
Ask your trainer to help you run a dot test. With the pump in low-pressure mode, if your machine has one, and with pure water only, place a piece of cardboard on the slats and fire the jet for a moment. Then look at the mark. A round dot means the orifice is in good shape. A teardrop or a fuzzy streak means it is worn. It takes less than a minute, and it teaches you what the jet does before you run a real job.
Tools You Will Use
- Clamps and weights for holding work
- Calipers and a tape measure
- Wrenches for changing head parts
- Cardboard for dot tests
- Shovel or vacuum for tank cleaning
- CAM software for loading programs
Common Mistakes
- Thinking of it as just water. It is a cutting tool.
- Skipping the clamp. Parts can shift or tip in the jet.
- Ignoring a drip. Small leaks can get worse quickly.
- Walking on a wet floor in the wrong shoes. Slips are one of the most common injuries here.
Check Your Understanding
A coworker gets a small nick from the jet. It barely bleeds, and he wants to put a bandage on it. What do you do?
Stop him, and get him to an emergency room. It may be an injection injury, which is a surgical emergency.
You spot a mist coming from a fitting. What do you do?
Stop the pump, bleed off the pressure and report it. Do not touch it.
Your trainer asks why the floor mats matter so much. What is your answer?
Overspray and mist make the floor slippery, and falling near a machine is a common way to get hurt.
A customer wants a heat-treated steel part cut without changing its hardness. Why is a waterjet a good choice?
It cuts without heat, so it does not change the hardness.
Key Takeaways
- A waterjet cuts almost anything, with no heat.
- Operators set up, run, check and maintain the machine.
- The jet can inject water and grit under the skin.
- Any skin contact is an emergency-room trip.
- Stop and bleed off the pressure for any leak.
- Slippery floors are a daily hazard.