How Does Waterjet Cutting Work?
Waterjet cutting is based on the principle of directing a fine stream of water onto the surface of the material through a special nozzle under extremely high pressure (4,000-6,000 bar / 60,000-90,000 psi). The stream leaves the nozzle at roughly three times the speed of sound and erodes the material being cut by micro-erosion.
For hard materials (metal, stone, glass) a fine-grained abrasive called garnet is added to the water; this combination increases cutting speed and effectiveness many times over. Soft materials (food, plastic, rubber) are cut with pure water.
Two Types of Waterjet Cutting
Pure Waterjet
- High-pressure water only
- Soft materials: plastic, rubber, paper, foam
- Food cutting (hygienic, no contamination)
- Cutting stream 0.1-0.3 mm
Abrasive Waterjet
- Water + garnet mixture
- Hard materials: steel, stainless steel, aluminium, titanium
- Marble, granite, ceramic, glass
- Composites, composite panel (aluminium composite, carbon fibre)
- Cutting stream 0.8-1.2 mm
Equipment Used
Waterjet cutting calls for advanced equipment if it is to be accurate and efficient:
- High-pressure pump — between 30 and 100 HP, it generates the 4,000-6,000 bar pressure the cut requires.
- Cutting head — made up of a diamond or sapphire orifice, a focusing tube (carbide) and a mixing chamber.
- CNC control system — programs the cutting path to high accuracy and coordinates the axis movements.
- Water treatment system — water conditioning by RO or softening to protect the pump and the nozzle from wear.
- Abrasive feed system — an automatic dosing unit for the garnet.
The Cutting Process — Step by Step
- The material is placed on the cutting table and secured with vacuum or mechanical clamps.
- The cutting path is programmed from the CAD file with CAM software (e.g. IGEMS, Contranest).
- The pump is started and the pressure is raised to the required value.
- The waterjet cuts the material along the programmed contour; where required, garnet is introduced by automatic dosing.
- The finished part is cleaned and quality-checked; the garnet sediment at the bottom of the tank is discharged periodically.
The Advantages of Waterjet Cutting
- NO HEAT ZONE — the cut is cold; the material does not harden, deform or lose its microstructure. There is no HAZ (heat-affected zone) in steel.
- HIGHLY VERSATILE — metal, stone, glass, composite, plastic, rubber, food... all of them are cut on the same machine.
- HIGH ACCURACY — ±0.1 mm tolerance as standard, ±0.05 mm repeatability on advanced machines.
- ENVIRONMENTALLY FRIENDLY — it produces no fumes, harmful gases or toxic waste. The garnet used is a natural mineral.
- MINIMAL WASTE — the narrow cutting stream (0.8-1.2 mm) means high material savings.
- COMPLEX SHAPES — internal holes, internal corners and tight contours are all possible; a pierce hole at the starting point is all that is needed.
Which Materials Are Cut?
- Metals: stainless steel, aluminium, copper, brass, titanium, Inconel
- Stone: marble, granite, travertine, onyx, quartz, natural and engineered stone
- Glass and ceramic (EXCLUDING tempered glass — see the exception below)
- Composite materials: carbon fibre, fibreglass, aluminium composite panel (ACP)
- Plastics and polymers: acrylic, PVC, polycarbonate, polyethylene
- Rubber, leather, textiles, foam
- Food: fish, meat, confectionery, cheese, sandwiches (hygienic cutting)
Industrial Applications
- Marble / natural stone processing — kitchen countertops, bathrooms, flooring, signage, mosaics
- Aerospace — production of alloy steel and titanium components
- Automotive — interior trim, insulation, electric vehicle battery components
- Architecture and decoration — bespoke logos, artwork, composite façades
- Food industry — portioning, slicing (pure waterjet)
- Spare parts production — small batches, prototypes, tight tolerances
Waterjet vs Other Cutting Methods
| Criterion | Waterjet | Laser | Plasma |
|---|---|---|---|
| Heat zone (HAZ) | NONE | Yes | High |
| Material range | Almost anything | Mostly metal | Conductive metal only |
| Thickness limit | 300 mm | ~25 mm (CO₂) | ~50 mm |
| Accuracy | ±0.1 mm | ±0.05 mm | ±0.5 mm |
| Environmental impact | Low | Medium (gas) | High (fumes) |
Cost Factors (Qualitative)
The main items in the operating cost of a waterjet are: pump electricity, garnet (abrasive) consumption, the wear allowance on the nozzle and focusing tube, and the water treatment system. The total hourly cost varies with pump capacity, material type and cutting parameters.
On heat-sensitive materials (titanium, stainless steel, some composites) the advantage of the waterjet is clear — because the cut is HAZ-free, no additional annealing or surface work is needed. For a precise cost and capacity analysis we recommend asking your supplier for a quotation specific to your application.
Is Waterjet Right for You?
You should definitely consider it in these situations: if you cut a wide variety of materials, if you have workpieces that are affected by heat, if you work marble / stone / glass / composites, if you need high accuracy and a narrow cut, and if low environmental impact is a criterion for you.