Ways
Posted by
gb
on 2002-04-21 16:40:09 UTC
Elliot Burke,
Box ways are usually made out of solid cast iron, that is bolted to
the machine base or columns. The ways are case hardened. On most of the
better machines that I have worked on they measure about 2 1/2 x 7" by
whatever length they are. They usually ride on turcite or Moglice wear
plates. The wear plates are ground flat, and have grooves cut in them,
for oil passages. The axis is held tight with gibs in all four corners
of the slide and two on the side of the ways. Pressure lubrication is
used, to feed oil to the ways. Most high dollar machines feed oil once
every six minutes of operation. The pressure is usually from 450 to 800
psi. Pressure lubrication usually runs to metering jets to supply a
precise amount of oil to each oiling point. On some slides you will find
way bearings. Way bearings are recirculation needle rollers that are
used for lighter duty machining. The precision of the machine is
determined by the machines geometries and the machines electronics. The
most accurate machines have glass farrand scales. I was a machine
repairman for many years. I once say a machine that was a Cincinnati
Hc-15 machining center, milling, drilling, tapping and reaming large
hydraulic valves for excavators. I had noticed a clunking noise while
the machine was operating. Days later, I found that the Y-axis ballscrew
nut, had come loose. It had run for days, without scrapping any parts
out, with a loose ballscrew. It had about 1/4' of slop in it when I
found it. This machine had glass scales. It was able to hold its
accuracy, because of its glass scales, which sent the machines actual
position to the control regardless of slop.
George
Tell us more about box ways.
What sort of sliding surfaces do they have turcite/teflon/babbit?
size and length of box?
pressurized lubrication?
how are the ways supported?
If they have more friction that roller bearings, does this affect the
ultimate precision of the machine?
Box ways are usually made out of solid cast iron, that is bolted to
the machine base or columns. The ways are case hardened. On most of the
better machines that I have worked on they measure about 2 1/2 x 7" by
whatever length they are. They usually ride on turcite or Moglice wear
plates. The wear plates are ground flat, and have grooves cut in them,
for oil passages. The axis is held tight with gibs in all four corners
of the slide and two on the side of the ways. Pressure lubrication is
used, to feed oil to the ways. Most high dollar machines feed oil once
every six minutes of operation. The pressure is usually from 450 to 800
psi. Pressure lubrication usually runs to metering jets to supply a
precise amount of oil to each oiling point. On some slides you will find
way bearings. Way bearings are recirculation needle rollers that are
used for lighter duty machining. The precision of the machine is
determined by the machines geometries and the machines electronics. The
most accurate machines have glass farrand scales. I was a machine
repairman for many years. I once say a machine that was a Cincinnati
Hc-15 machining center, milling, drilling, tapping and reaming large
hydraulic valves for excavators. I had noticed a clunking noise while
the machine was operating. Days later, I found that the Y-axis ballscrew
nut, had come loose. It had run for days, without scrapping any parts
out, with a loose ballscrew. It had about 1/4' of slop in it when I
found it. This machine had glass scales. It was able to hold its
accuracy, because of its glass scales, which sent the machines actual
position to the control regardless of slop.
George
Tell us more about box ways.
What sort of sliding surfaces do they have turcite/teflon/babbit?
size and length of box?
pressurized lubrication?
how are the ways supported?
If they have more friction that roller bearings, does this affect the
ultimate precision of the machine?