On Tue, 3 Apr 2018 17:12:03 -0700, Bob La Londe
wrote:
I am curious. What kind of oiling interval you think is suitable for a
continuously running CNC milling machine?
One which may run for an extended period reciprocating rapidly over a
short range of its travel.
I have 4 machines with automatic oilers, and I just purchased a 5th.
Of the 4 machines I already have one was setup by the manufacturer to
apply oil to the ways and ball nuts every 15 minutes with an electro
mechanical clock timer. It has wath appear to be cast iron ways, and
inspite of an original service date of 1984 the ways are in pretty good
condition. If it was on all day it used about a pint a day of way oil.
Maybe a hair more. It has other issues, but the ballscrews have almost
no backlash and the way surfaces look very good. It does have oil
metering emitters at every lubrication point. This limits the amount of
oil delivered in a cycle, and assures lubrication points oil
appropriately as long as there is no air in the lines. There hasn't
been any air in the lines in years. I did recently change it over to a
more modern programmable electric oiler, but the cyle rate is about the
same, and I timed the duration to put out the same amount of net oil.
The other three are newer being 2-5 years old. One has plane cast iron
ways, and the other two have square profile linear ways. They are all
set to oil about every 20 minutes for about 15 seconds. They do not
have emitters. Just open oil ports to the lubrication point. I get
atleast some oil at every lubrication point every cycle.
Now to get to that fifth machine. Its a brand new machine. I purchased
it with a bunch of options including an automatic tool changer,
automated power draw bar, full enclosure, and an automatic oiler. This
is a high end "pro/hobbyist" machine so I get to install all the options
and setup the machine myself. In reading the manufacturers notes it
says it should have the electric oiler interval set at 240 minutes (4
hours) and it should pump oil for only 5 seconds. This set me back a
bit so I asked the companies tech support about it and I got a general
non-committal reply. "The oiling schedule that we set is only a
starting point. It is adequate at this setting, but you can set it for
whatever you would like."
The oiler itself is just another Chinese automatic electric oiler
similar to the ones on my other machines.
In the specs for the machine it says, "The sliding dovetailed ways are
hand-scraped and designed to withstand high loads and dampen vibrations.
The ways have bonded PTFE filled acetyl sliding surfaces, hand scraped
by skilled machine builders. Similar to brand name compounds such as
TurciteŽ or RulonŽ, PTFE compounds provide low friction and long life."
Is that way spec adequate to explain why they recommend such a short oil
application period and such a long lubrication interval? Or have I been
grossly over lubricating all my other machines for years?
The oil spec is just iso 68 way oil and includes a list of suitable oils
including Mobile Vactra #2 which is what I use in all my other machines
and with a dispenser even on my manual machines.
If their oiling recommendation is "generally" adequate do you think it
takes into account localized scrubbing from the point I raised near the
beginning of this post? Because I do complex 3D machining almost
exclusively my machines may run for an extended period reciprocating
rapidly over a short range of its travel on any given axis.
I would like to read your opinions, but do please read the whole post
first.
The new machine has synthetic way lubrication points already..adding
oil simply provides more slip. Since it isnt being scrubbed off..less
is needed.
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus