How Thick is Your Oil? I Want Your Opinion
POST DATE Dec 11, 2014
AUTHOR Dean Maier
Remember Opa, my Grandpa? The reason I ask is because I remember him telling me the same thing I wrote about in my last article—“the day you quit learning, is the day you die.” So in this article I’m looking for some audience participation; what viscosity oil do you run in your saw guide system?
And the reason I’m asking is because I want to learn something new from you.
Recently, we had a system go online and experienced several issues. The water flow meters quit working resulting in the oil volume going too high and then too low. The oil plugged up the guide holes and stopped the water flow, which is what we believe caused the flow meters to fail. Fail is probably misleading, as it’s more likely that they stopped reading due to little or no water moving through. Several people told us they were actually running much thinner oil than what they originally told us, so it’s likely that there were a bunch of issues going on at the same time.
Troubleshooting is like a game of clue, you have to ask the right questions in order to find a solution. If you think that Professor Plum did it in the library with the candlestick holder but he doesn’t have the candlestick holder to begin with, what then?
Most of our customers advised me that they were running a SawGlide100 in their old systems, however now I've come to find out that they’re running 32. This got me thinking about high speed bearing applications and the light oil they have to run in order to prevent the viscous drag from generating heat. A 21” saw, running at 3600 RPM basically has the cutting edge running at 19,800 feet per minute. Running thick oil on something running this fast then has a very large potential for generating heat because the viscous shear. So does running thinner oil help prevent heat from being developed in the first place?
This is one of those learning opportunities that pops up now and again…
As two moving surfaces run past each other they generate friction, so you put a friction modifier in between (oil) to reduce the coefficient of friction. As things move faster, oil viscosity requirements become lighter because it develops a hydrodynamic wedge between them more easily. If the oil is too thick, then the resistance of the oil to move between these two moving surfaces starts to create friction (heat). In saws, heat is what we’re trying to eliminate, or prevent from developing in the first place.
One of the interesting things we found however, after getting the lines, guide ports and everything cleaned out for 22 saws (11 per arbor), was they were running a total of 3.2 gallons per minute in the cut and only 0.625 gallons per hour of oil AND it seemed to be working fine. So does running a 100 weight oil, which has a very high film strength compared to a 32 weight oil, allow you to run less oil?
I’m very interested in hearing from as many of you as possible, so we can all learn something new together. And there’s no better laboratory than the ones in the real world, with real world conditions. So help me keep learning and comment below, because I’m not ready to die, just yet.
Author: Dean Maier
Dean has been in the automated lubrication business for 25 years, with 85% of that time spent in forestry applications. We are delighted to have his insight with this latest blog.
Industrial Autolube International Inc.
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