Omax JetMachining Center 2626, Operator'S Manual

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Maintenance OMAX JetMachining® Center Operator’s Guide
400433D-EN 4 - 11
Figure 4-14: Chipped Orifice Assembly Jewel
Particles of debris traveling at high speeds through the orifice can easily chip or damage the jewel by
hitting an edge of the orifice. Garnet in the vent under the orifice assembly can cause premature wear to
the mixing chamber which in turn allows garnet to get past the orifice assembly, resulting in the jewel
chipping. Whenever the vent under the orifice plugs, garnet may end up on top of the orifice assembly.
This might also cause the jewel to chip.
Variables including elevated water temperature and pH, plus the presence of scaling ions such as
calcium, magnesium, or silicon. Ions can cause scale to build up in and around the internal diameter of
the orifice. Mineral deposits, or scale, in the internal diameter of the orifice can form a hollow cone
surrounding the small hole in the center of the jewel. Eventually, this buildup results in poor jet quality.
Figure 4-15: Plugged Jewel Orifice
If in-line filters are not used, particles that are too large to pass through the orifice will plug or damage it,
causing the pump to fault. A fine particle filter, called the “last chance filter,” is installed just before the
orifice to prevent particles upstream in the high-pressure system from entering the orifice.
A misaligned jet stream is one that cannot pass through the mixing tube without touching the inside bore
when run at low pressure. Garnet, grit, dirt, or other contamination trapped between the orifice mount
and the carbide disc, or between the disc and the carbide mixing chamber, can throw the jet out of
alignment, causing premature wear on the mixing tube.
If a jewel is damaged, misaligned, or not producing a well-formed jet, the life of the mixing chamber disc
and the mixing tube will be dramatically reduced if the damaged jewel is not replace. If orifice chipping is
a chronic problem and not corrected by using filters or following proper procedures, consider using a
diamond orifice assembly. Diamond orifices are highly resistant to chipping from particle impact and
have a much longer wear life. Additional jewels may be purchased from OMAX’s Customer Service.
Mixing Chamber Disc
The mixing chamber disc (Figure 4-12) is also a consumable item requiring close inspection.
Magnification may be needed to accurately detect wear or disc damage. Begin by measuring the internal
diameter of the hole in the mixing chamber disk using a 0.026" (0.66 mm) pin gauge. The internal
diameter of this hole for a new mixing chamber disc is 0.020" (0.51 mm). To inspect the disc, measure
the internal diameter of the hole in the mixing chamber disc using a pin gauge. If the internal hole
diameter is
greater than .030" (.76 mm), the disc should be replaced.