When I picked up my okamoto 124n, it was full of oil. I used this parker filtration unit to filter the oil into drums. When I installed, I cleaned the sump, the intake filter and I ran it through the filter system again. Ive got the 25 micron inlet and 10 micron outlet filters installed. Any grinder users out there have an opinion on filtering grinder oil to reuse?
Hello:
The theory is that new hydraulic oil dissolves and collects varnish deposits within the system up until a equilibrium concentration has been reached in the oil. Once a equilibrium has been established the process stops. It is analogous to flushing a boiler containing dissolved mineral deposits with distilled water. The distilled water will remove the minerals until a equilibrium has been established in the flush water.
Oils can form a solid film when exposed to heat, static electric discharges, oxygen, or dissolved metals that act as catalysts. There are additives included in the oil formulation that slow down the process. Eventually the additives are used up.
A flushing oil may be needed if the hydraulic system is operated too long without changing the oil. Changing the oil at regular intervals should prevent the need for using a flushing fluid.
I do not know for certain how much of this is true. There is one oil filtration company that has a website detailing the above argument. They sell a filtration system which they claim will remove the degraded oil products from the oil and allow it to be reused. A replacement additive also needs to be purchased to restore the anti-oxidation chemicals.
My experience is that the hydraulic spool valves need to be disassembled once they jam from sitting too long. The flushing oil is used in the hope that the spool valves can be freed without disassembly.
The "old" oil does not seem to be a problem provided that the grinder is used on a weekly basis. If the machine is going to be sitting idle for months a oil change may be needed to prevent the accumulated varnish deposits from jamming the spool valves. The hydraulic pistons do not seem to be sensitive to the presence of old oil. There is a possibility that the o-ring and U-cup seals may become brittle. This may be a result of sitting idle rather than from the contaminated oil.
The ways on the Okamoto grinder are protected from any grit in the oil by the gravity fed oil system. The oil is pumped to the sump at the top of the column and then filtered by the wool wicks that draw the oil from the sump to the way oil feed lines. The spool valves and hydraulic cylinders are exposed to the grit in the oil.
The other major problem is rust. All used oil contains water and dissolved oxygen. New oil contains additives that form a film on metallic surfaces that will slow down the oxidation of the exposed metal. The additive is eventually used up. Once this happens rust will form and jam the valves if the grinder is left idle. The solution is either to change the oil or use the grinder weekly to prevent the rust film from building up. The flushing fluid will not remove rust.
The return oil line outlet is kept 2 inches below the oil level in the tank to reduce the pickup of water vapor and air. If you operate the grinder with a low oil level rust is more likely to be a problem.
On older grinders it is possible to upgrade the machine hydraulics to continuous filtration by replacing the hydraulic sump drain plug with a quick disconnect fitting and then running a hose from the fitting to a external pump and filter unit. The oil is then returned to the tank through a modified tank fill cap. The cap is set up to insure that the return line is below the tank oil level.
The advantage of this system is that the water and abrasive slurry at the bottom of the tank is continuously being removed. The filtration system consists of several stages. There will be a bag or spin on filter to remove grit, That will be followed with a water separation chamber with a automatic drain. The last filter may contain activated carbon or a molecular sieve to remove the degraded oil products.
Robert