TL;DR
A widening kerf, taper on cut parts, or reduced cutting speed nearly always means the orifice jewel or focusing nozzle is worn. Replace both as a set when cut quality degrades.
What you might see
- increasing kerf width over production run
- cut taper worsening on thick material
- cutting speed has to be reduced to maintain quality
- visible wear or chip on the orifice jewel under magnification
Likely causes
Orifice jewel erosion from cumulative water passage (typical life 40 to 100 hours with good water quality)
Focusing tube erosion from abrasive garnet stream
Contaminants or scale in the ultra-high-pressure water stream damaging the orifice
Incorrect jewel seating allowing micro-movement and accelerated wear
Required tools
- High-pressure waterjet wrench set (typically 9/16" and 1-1/8" flats)
- Magnification loupe or microscope for orifice inspection
- Pin gauge set for nozzle bore measurement
- Torque wrench
- Replacement orifice jewel and focusing tube assembly
- LOTO kit
Safety first
- Ultra-high-pressure water at 60,000 psi will penetrate skin without sensation. Never expose any body part to a pressurized waterjet stream.
- Confirm zero pressure on the gauge before loosening any high-pressure fitting. Do not rely on the pump being off alone.
- Garnet abrasive dust is a respiratory hazard. Wear appropriate respiratory protection when cleaning the cutting area.
Procedure
- 1
Stop the pump and confirm system pressure is at zero on the high-pressure gauge.
Warning: Waterjet cutting pressure exceeds 60,000 psi. Never loosen any high-pressure fitting until the intensifier pump is off and the pressure gauge reads zero. - 2
Lower the cutting head to a safe working height and lock the Z axis.
- 3
Remove the nozzle body from the cutting head by unscrewing the retaining nut using the correct wrench size.
- 4
Inspect the orifice jewel under a magnification loupe. Look for a worn flat spot or chip on the bore edge, which indicates it is past service life.[1]
- 5
Disassemble the nozzle and remove the focusing tube. Measure the bore diameter with pin gauges. Focusing tubes are typically replaced when bore grows 0.010 inches beyond nominal.[1]
- 6
Install a new jewel and focusing tube assembly. Torque the orifice retaining nut to the value specified on the Flow nozzle assembly drawing.
- 7
Re-install the nozzle body, prime the water circuit, and check for any high-pressure water leaks before cutting.
- 8
Run a test cut on scrap and measure the kerf width with a digital caliper to confirm quality is restored.
Sources
Flow International Flow Mach 200 / 500 / 700 Waterjet Cutting Machine general technical documentation, Flow International
Flow International waterjet maintenance guide, orifice and nozzle inspection and replacement procedures (general)
More guides for Flow International Flow Mach 200 / 500 / 700
How to fix abrasive feed interruption on a Flow Mach 200 / 500 / 700 waterjet
Abrasive stoppages are usually a clogged abrasive line, empty hopper, or a worn or blocked metering orifice. Check the hopper level first, then inspect the abrasive line from hopper to nozzle.
How to troubleshoot low intensifier pump pressure on a Flow Mach 200 / 500 / 700 waterjet
Low intensifier output pressure is usually worn high-pressure seals, check valves, or a damaged intensifier cylinder. Inspect the check valve cartridges and HP seals before condemning the cylinder.
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