Waterjet cutting systems rely on high-pressure pumps to generate the required water pressure for precision cutting. The two primary types of pumps used in waterjet technology are intensifier pumps and direct drive pumps. Each operates on a different principle, offering unique advantages depending on the cutting application.
Intensifier Pump
Intensifier pumps amplify pressure using the principle of pressure intensification.
Working Principle:
- When pressure is applied to one side of a cylinder, the opposite side experiences the same pressure if the surface areas are equal.
- If the surface area on the smaller side is halved, the pressure on that side doubles.
- Typically, the ratio between the larger (oil pressure) and smaller (water pressure) surface areas in an intensifier pump is 20:1.
Pressure Generation:
- Pressure is created by restricting water flow through the orifice in the cutting head.
- The system maintains pressure until the orifice size exceeds the pump’s capacity.
Performance & Overstroke Protection:
- Small orifices: The pump cycles slowly to maintain pressure.
- Larger orifices: The pump cycles faster to sustain flow and pressure.
- Oversized orifices: The pump may exceed its design limit, triggering an “overstroke” error, causing it to shut down.
- Leaks in the water circuit can also lead to an overstroke condition, as they divert water away from the cutting head, forcing the pump to compensate by increasing its cycle rate.
Cycle Rate:
- Under full capacity, intensifier pumps operate at 50–60 strokes per minute.
Direct drive pump
Direct drive pumps function similarly to car engines, using a motor-driven crankshaft to generate pressure.
Working Principle:
- A motor drives a crankshaft attached to multiple offset pistons.
- As the crankshaft rotates, the pistons move within their cylinders, generating pressure.
- The pressure and flow rate depend on the motor's speed.
Performance & Applications:
- Operates at 1,750 revolutions per minute (RPM), significantly faster than an intensifier pump.
- Commonly used for lower-pressure applications (typically 55,000 psi and below).
- Requires longer maintenance intervals than intensifier pumps.
Comparison to Intensifier Pumps:
1.Cutting Head Control:
- Direct drive pumps can only support multiple cutting heads if all heads are cutting the same part simultaneously.
- Intensifier pumps can operate multiple cutting heads on different machines independently, adjusting stroke rates to maintain pressure.
2.Flexibility:
- Intensifier pumps allow more flexibility in cutting sequences, making them ideal for multi-machine operations.
- Direct drive pumps are more limited in versatility but work efficiently for simpler, high-speed cutting tasks.
Both intensifier and direct drive pumps have their own strengths, making them suitable for different applications in waterjet cutting. Intensifier pumps offer higher flexibility, independent cutting head operation, and consistent pressure maintenance, making them ideal for high-precision and multi-machine setups. On the other hand, direct drive pumps provide faster operation and lower maintenance at lower pressures, making them a great choice for high-speed, single-task cutting applications. Choosing the right pump depends on the specific requirements of the cutting operation.