The Chiller System
The Chiller System on a Fadal was originally designed to insure the spindle would
stay cool (no more than 4 degrees higher than the casting). It was and still is highly needed for spindle speeds
above 7500 rpm's.
Then a few years later along came the High Speed Ball Screws and table travel
up to 400 ipm and rapid travels in excess of 1000 ipm. To keep these coarse threaded screws cool during constant
high speed operations the screws needed
to be cooled also, so they were plumbed in to the spindle chiller.
The idea was good. The problems it caused was bad!
Ball Screws were ground for a seal finish so the chiller fluid could be forced
through the inside of the screw and returned to the fluid storage tank. This
kept the screws cool and kept machining tolerances under a tight control.
The Chiller fluid was being fed through the head cavity around
the spindle, the chemicals in the fluid was washing out micro
particles of the cast iron form the head and mixing them with the fluid, this made a very fine
lapping compound that when combine with the pressure of the seals on the ball screw caused the
seals to cut grooves on the end of the screws. When the
grooves become deep enough, seal failure accrued and the ball
screw was already beyond any inexpensive repair.
The seal failure also caused many other problems. Chiller
fluid would wash out the grease pack in the thrust bearings and cause High noise during table,
sadly or head movements. This also caused finish problems and higher loads on the axis motors and
amplifiers. If the problem wasn't found quick enough, the
loss of chiller fluid could cause irreversible problems to the chiller pump and even the
premature spindle bearing failure.
Poor positioning and high backlash compensation would make a trouble call necessary and the
problems could be found. Most of the time the repair cost had already became very high. Because the
cost of repairing a damaged ball screw along with the down time involved far exceeded the cost of a
new replacement not to mention all the other parts that required replacing.
The Chiller Filter
Install a filter in the return line just before the
storage tank insured clean chiller fluid was being supplied to the ball screws and the spindle.
The first units were installed on VMC with heavily contaminated chiller fluid and they turned
the filters black with dirt, rusted and corrosion deposits within just a few hours of cycle time.
The pressure gauges on the pumps would strut around 20 psi and within an hour be passed 45 psi.
But still filter containers had their problems
Not being able to see through a steel filter unit left the problem that if you couldn't see that
their was problem, then their wasn't a problem (Out of sight, Out of mind!)
It was decided to use a transparent poly carbonate filter unit with a low micron filter element
so that the filter was fully visible and could be seen when it started to change color from excess
The filter unit mounts easily on the outside of the chiller cabinet. The pressure gage requires
a 2 1/8" hole to be cut or punched into the outside edge of the cabinet and then plumed.
The Kit Contains:
Poly carbonate Filter Unit
1 Liquid Pressure Gauge, 0 to 100 psi
15' Nicole 3/8" Chemical Tubing
All required Comozzi Quick Connect Fittings
All Thread Reducer adaptors, Teflon Thread Tape and complete Instructions
Note: Older VMC's with black rubber chiller hose will require barbed