Saturday, October 8, 2011

Waterjet Machining

Waterjet Machining -- Its Time Has Come
Waterjet machining has been around for many years, but has traditionally been viewed as a specialty process with limited applications. However, recent advances are making waterjet machining practical for applications never before considered.

The waterjet cutting machine uses a stream of water and abrasive particles, such as garnet, to perform the cutting operation. The waterjet cutter takes city water (typically 80 psi), and through the use of an intensifier-type pump, pressurizes the water to 55,000 psi. When the abrasivejet cutting head is enabled, the water flows through a 0.010-inch diameter orifice into a mixing chamber. As the waterjet stream enters the mixing chamber, it creates a partial vacuum that draws the flow of abrasive particles through the abrasive delivery line. The abrasive particles combine with the waterjet stream to create the high energy abrasivejet cutting stream. This stream exits the cutting head at a velocity of up to 3,000 feet per second. Today's waterjet cutting machines are CNC controlled for accuracy, repeatability and ease of setup.

Waterjet machine
Advantages of waterjet machining:
- Cuts through any substance

- Material yield is maximized. Parts can be nested very close to each other in order to maximize material utilization. In some cases, pieces can even share the same cutting line.

- No heat-affected zones the waterjet process does not generate the same level of heat as other processes. As a result, the properties of the materials being cut do not change. The waterjet heat is concentrated so much that it literally dissipates into the chip or removed material. He adds that there will be no burn marks on parts that have been cut by the waterjet.

- No start hole is required The waterjet nozzle is placed where the cutting is to begin. The waterjet burrows its own hole through the material, eliminating the need to drill the material beforehand.

- Burr-free edge quality. The waterjet cuts with very little force, so the amount of burr generated is either very small, or non-existent.

- Eliminates secondary operations. In many cases, the need for secondary operations, such as sawing, milling or drilling can be eliminated. Etching of numbers can be done during the waterjet process, eliminating the need for a separate etching operation. In addition, because the waterjet cuts without heat, there is no need to anneal the material after machining.