The WAS Technology

Using the water abrasive suspension (WAS) cutting process with the aid of a water jet and sharp-edged abrasive material – preferably very fine garnet sand – even high-strength steels up to 30 cm thick and reinforced concrete up to a metre in thickness, as well as a wide variety of other materials, can be effectively and precisely parted. The special features of this process are: the cuts are executed in a contact-free manner, with no significant heat generation or deformation, regardless of the material in question, and can also be performed using remote manipulation at distances of more than 1,000 metres. Only very thin parting seams are produced, with low secondary waste. This technology has even been proven underwater at depths of up to 600 m.

please click to view animation (~1.5 MB, MPEG4)       Flow speed in hose: 3-10 m/sec corresponding with 10-36 km/h   Flow speed at the nozzle: 300-700 m/sec corresponding with 1000-2500 km/h

The particular know-how that we have developed is located in the valve technology and in the mixing of water and abrasive material at high pressure. The important parts of the equipment include a high pressure pump, a mixing unit for the abrasive material, high pressure hoses and a cutting nozzle of 0.5 to 1.3 mm diameter. The water jet and the abrasive material are pushed through the cutting nozzle. The potential energy represented by the pressure is converted in the nozzle into a cutting jet with a velocity of several hundred metres per second. With the water the abrasive material particles are accelerated and these cut like a knife through the workpiece material.

With the aid of cutting devices (robots, ROV's or manipulators) it is possible to control the cutting processes from a large distance so that peoples’ lives are not endangered in explosive areas or other sensitive areas. Depending upon the intended application and requirement we offer cutting equipment with a range of pressure levels from 450, 700, 1,200, 1,500, 2,000 to 2,500 bar.

The advantages

	Cutting tasks in air and underwater
	Independent of material steel, glass, concrete, composites, sandwich structures, etc.
	Only one hose to the cutting nozzle
	High cutting velocity with high accuracy
	Minimal cutting seam width of less than 1 mm possible (low secondary waste)
	Minimal consumption of abrasive material
	Cold process without thermal zones or burning
	Cut is free of dust or gas
	Low reactive forces
	Good remote manipulation capability
	No component modifications or deformations measurable
	Certificate for cutting tasks in explosive areas Bundesamt für Materialforschung und -prüfung (BAM) (Federal Office for Materials Research and Testing)

Water Jet Cutting Technology - Suspension vs. Injection

Cutting using the Abrasive Suspension (WAS) method enjoys widespread use in industrial applications. The method is primarily used for the discrete and urgent removal of highly explosive structures that often involve the risk of consequential damage and operational stoppages lasting several days.

Two different water jet cutting technologies are available for industrial applications: the suspension jet cutting technique and the injection jet cutting technique. These two techniques are similar, but differ fundamentally in terms of their appplication and performance. Again and again, industry reports extremely unsatisfactory results when the injection technique is used. It is entirely unsuitable for specialist applications such as cutting copper, slag etc.

The injection technique is ideal for making fine, precise cuts in filigree materials and therefore often uses cutting tables that are suitable for this purpose but unsuitable for cutting heavy structures as required by industry. The high cutting performance demands made by industry in terms of strength and speed necessitate technical parameters that only the suspension jet cutting process can offer.

By way of illustration:

Left side: WAS technique (Water Abrasive Suspension jet)

2-phase system out of water 90% and abrasive 10%

Right side: WAIS (Water Abrasive Injection jet)

3-phase system out of air 90%, water 6%, abrasive 4%

The production of pre-mixed abrasive suspensions represents a further advance in the injector jet process and increases its effectiveness significantly. While water abrasive injector jets are produced in a mixing unit as per the principle of a water jet pump, with the water jet suspension method, an abrasive suspension held under pressure is pushed through a nozzle to release its pressure.

Suspension jet systems currently available work with a water pressure that is significantly lower than that used for the injector jet and correspondingly higher water and abrasive mass flows. This means that the suspension jet cutting technique is more powerful and requires lower quantities of abrasive and water, and this has a positive impact on financial investment, the time factor and the environment.

Comparison of performance

Result

With a comparable output, the WAS technique is 2.5 x faster and requires less abrasive.

The WAS Technique as illustrated by a 2000 bar System and a Nozzle Diameter of 0.6 mm

Input

- Working pressure 2000 bar

- Water volume flow 10 l/min

- Abrasive volume flow 1 kg/min

- Hose diameter 8 mm

- Flow speed 3.3 m/s

Action

- Nozzle diameter 0.6 mm

- The diameter change behaves potentially to the flow speed => (8/0.6)² => 178

- Pressure converted into speed

Output

- Flow speed 587 m/s

- Hydraulic output 32 kW

- Restoring force 100N

Advantages of the WAS Technique

	Cold cutting without thermal influence zones (certificated by the German Federal Office for Materials Research and Testing - BAM)
	Rapid precision machining of materials including non-conductive materials
	Extremely narrow cutting kerfs for reduced waste, particularly important in respect of high-strength and expensive materials
	Reduction of cutting costs per metre
	High number and broad diversity of applications