Some Downsides to Waterjet Cutting. As with a laser beam, the waterjet cutting stream is most effective when it is most concentrated. But when cutting through tubing, voids can cause the stream to diffuse, rapidly losing its accuracy and cutting ability.
Some of the most common problems are overstroking, water leaks, and short seal life (see Figure 1). Three other common problems with intensifier-based waterjet systems are hydraulic pressure failure, low water pressure, and hydraulic temperature overheating.
The most common potential risks are described below: Perforation, cutting or severing of a body part. It is caused as the result of the direct exposure to the pressurised waterjet. These types of injuries are always very serious and can be fatal.
This means that the pressure is over 4000 times greater than the normal atmospheric pressure (1 bar). Hard materials cannot be machined with simple water jet machining. It is only suitable for softer materials such as rubber, ABS, leather, wood, and plastics.
Materials That Waterjets Cannot Cut
Tempered glass cannot be cut because it has internal tension. It breaks itself when a cut crosses its tension zones. A piece of tempered glass that shattered after a waterjet started cutting it.
We often get asked what water jets can cut and our response can be to just mention what can't be cut – diamonds and not much else. However, even diamonds can be cut if the water jet is powerful enough, as this video demonstrates.
Disadvantages of Waterjet Cutting
Though waterjet cutters can cut virtually any type of material, they often take longer to cut materials than traditional cutters. Low-quality waterjet orifices are known to break down, which could result in a loss of time and productivity and disrupt the cutting process.
There are different consumables, different power requirements, cost of water, and most importantly, the cost of abrasive. Garnet abrasive can account for as much as 75 percent of the total hourly operating cost of a waterjet cutting system.
Accuracy of a Waterjet Cut
More commonly a tolerance of +/- 0.005” is achievable, and this tolerance can be met in thicknesses beyond 1 inch. However, this tolerance still incurs extra charges for slower feed rates and more setup time. For these reasons, a tolerance of +/- 0.010″ is cheaper than +/- 0.005”.
Common hazards and risks include the water jet piercing the skin, being hit by flying debris and exposure to noise. Other hazards associated with high pressure water jetting include working in confined spaces, fall hazards, respiratory and eye hazards, electric shock and potential exposure to hazardous chemicals.
While there are several factors that can affect the hourly cost of running a waterjet, on average, it can cost anywhere between $20/hr - $40/hr to run a waterjet with a single abrasive cutting head at 60,000 psi (does not include labor or capital repayment).
High pressure of water stream can cause eyes injuries. Protect your eyes, when you work near the machine. Dangerous noise can cause hearing loss Protect your ears, if you work near the machine. The electrical enclosure and motor junction box can present an electrical shock hazard.
Nozzle Wear: The intense conditions inside the cutting nozzle can lead to its rapid wear, affecting precision and efficiency. Abrasive Feed Issues: Incorrect abrasive flow can compromise cutting speed and quality. Clogging of the Cutting Head: Obstructions in the cutting head disrupt water flow, leading to subpar cuts.
Many waterjet manufacturers advertise accuracies ranging from +/-0.0005” to +/-0.0015”. It is necessary to understand that this is referring to the positional accuracy of the machine rather than the accuracy of the parts it cuts, and there is a significant difference between the two.
The high-level answer is that abrasive waterjets can cut through 12 inches of most materials. Many users report cutting material even thicker than that. Most abrasive waterjet cutting, however, is done in material that is 3 inches thick or less.
There are some things that a waterjet cannot cut, including things like diamonds and tempered glass. Most commonly, waterjets are used to cut things like tiles, ceramic, and non-tempered glass. Waterjets are a great tool that can make it easy to cut materials that might not be easily cut with more rigid tools.
Process. There are six main process characteristics of water jet cutting: Uses a high-velocity stream of ultra high-pressure water 30,000–90,000 psi (210–620 MPa) which is produced by a high-pressure pump with possible abrasive particles suspended in the stream.
Apart from controlling costs in operation, we must also consider the initial investment cost. A typical waterjet machine will cost about half what a CNC Laser will cost for a similar size and quality.
Jet Boating
The risks and hazards include but are not limited to collisions with obstacles (rocks, trees, debris, other vessels), high speed manoeuvres, grounding the Jetboat, capsize, and mechanical failures.
High Speed Efficiency: At high speeds, waterjets can be more efficient than propellers. This is because there are no underwater appendages creating drag.
More time cutting means less output. Orifice Failure – Low quality waterjet orifices have a tendency to break down and disrupt cutting, resulting in lost time and productivity. Greater Thickness, Less Accuracy – The thicker a material the further the stream is away from the nozzle at its point of impact.
The precision of a cutting machine is normally determined by comparing the actual measurements of the resulting part compared to the programmed part size. Due to less heat distortion, waterjet cutting is the most accurate, followed by laser and finally plasma.