Bet on waterjet: Inspection Efficiency

Waterjet technology, which uses high-velocity water mixed with garnet, can cut any thickness of material that fits under the head.

Those employed in metalworking industries are probably familiar with abrasive waterjet technology. However, many likely do not understand its unique capabilities and benefits. When we started Savannah (Georgia) Machinery Works in 2010, we had the opportunity to examine different manufacturing technologies and determined that waterjet cutting would be critical to the success of our startup.

Almost every component in gas turbine combustion hardware starts life as flat stock that is cut, formed and welded. Obviously, the flat stock has to be cut before we can do any forming and welding, so selecting the appropriate metalcutting machine tool was an important decision.

Most of our cut parts have nonrectilinear shapes, which require a CNC machine capable of producing complex shapes with different angles and radii. All current technologies, such as laser, oxy-fuel, plasma and waterjet cutting, have large tables, making them capable of holding entire sheets of flat stock.

Because programs were necessary to control the machine, we wanted to ensure that it was easy to program. Every cutting technology employs similar software that accepts various CAD files, making programming easy. In all cases, it was as simple as selecting the profile, telling the machine where to start, providing basic information about the workpiece material and pushing the start button.

Different Dimensions

The next consideration was material thickness. This is where we started to see distinct differences in capability between the thermal machines and the waterjet.

Our materials range in thickness from 1mm to 25mm, which presents a challenge when trying to select a style of machine. Thermal machines that worked well with sheets 1mm or 1.5mm thick, for example, using laser technology were not capable of cutting materials 15mm or 18mm thick. And the machines that could cut thick materials using plasma and oxy-fuel technology did not provide the specified cut quality. Waterjet was the only technology capable of delivering the desired profile definition over our range of material thicknesses. Waterjet technology, which uses high-velocity water mixed with garnet, can cut any thickness of material that fits under the head. An added advantage is that changeover from a thin to thick material is simple and done entirely through the control.

Pictured is the lower half of a gas turbine combustion component. The rectangular tabs and extra stock must be removed, which is done with a 5-axis abrasive waterjet machine at Mitsubishi Hitachi Power Systems Americas. Image courtesy of C. Tate