DCR

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DCR means Drain, Clean, and Recharge. The fluid in a system undergoes DCR when testing shows that the fluid has reached the point where making additions to the fluid is no longer effective, or when the level of bacteria or mold has become unmanageable.

Periodic checks of the system on a regular basis are strongly recommended. The size of the system will indicate the frequency and type of testing.

1. add biocide

2. pump out fluid

3. remove chips, swarf

4. fill with fresh water &
sump cleaner

5. circulate solution,
spray on surfaces

6. pump out cleaning
solution

7. fill with fresh water

8. rinse all surfaces

9. repeat rinsing as
many times as
needed

10. change filters

11. refill with fresh MRF

stopping the "cascade of contamination"

What is the procedure for DCR?

Before starting this procedure, have one of your oilers do a complete lubrication check on the machine tool, making sure all reservoirs are full and all grease zerks charged. In addition, make sure all cleaning personnel are properly clothed and gloved (proper personal protective equipment) to avoid any dermatitis from the cleaners.

First, a cleaner containing a biocide that will work effectively with the contaminated (dirty) fluid should be added and circulated thoroughly. Then the old fluid must be pumped out and disposed of. Delivery lines should be drained if possible.

All chips and swarf should be removed from flumes, trenches, lines and sumps. Covers and guards can be removed to give access to hidden areas for cleaning. (Note: Cleaning crews should be given additional instruction about additional hazards presented by the removal of covers and guards).

The system is filled with fresh water and sump cleaner and agitated.

This solution is circulated and sprayed at high pressure on all contaminated surfaces, especially machine tool surfaces that are not wetted by the normal flow of the circulating MRF. If a high-pressure spray cannot remove buildup, an attempt should be made to scrape it off manually.

The cleaning solution is then pumped out and the system refilled with fresh water. The water is circulated thoroughly and rinsed off all surfaces. The rinse water should be dumped and the system refilled with fresh water, again circulating and thoroughly washing/rinsing down all appropriate equipment. This should be done as many times as necessary to assure complete removal of the cleaning solution.

The addition of a small amount of MRF concentrate to the rinse water may help to protect against rapid rusting while the equipment is being rinsed.

Change all filters in the MRF system. Wipe out the filter canister.

Immediately after the last rinse has been pumped out, refill with fresh MRF, circulate the MRF, and wet those surfaces that may rust. Also run all axes through the full extent of their travel. This will lubricate all ways and remove fluid from the bearing packs.

After the machine tool has been refilled, the MRF should be turned on and the fluid coming out of the coolant lines caught before it returns to the sump. Only after clean fluid can be seen coming out of the lines should the fluid be allowed to drain into the sump.

This spent fluid should be disposed of and not returned to the machine sump. Wash-off hoses connected to the MRF system should also be drained to prevent contaminated fluid from returning to the system. A note should be made and left on the machine tool as to when the fluid was changed.

If the machine sours again within a short period of time (less than a week), all chips should be removed, and the machine tool should be refilled with a cleaning solution and circulated for an hour. The machine should be pumped and rinsed at least twice. Before the rinse water is pumped out, it should be circulated though the machine.

In certain cases, even this will not be enough to get at the source of contamination. Disassembly and removal of chip conveyors will be necessary. The buildup of salts and oil (similar to a bathtub ring) will have to be either scraped off or blasted off the surface with a high-pressure washer.

Sumps of machine tools such as saws, which process raw material to be used by other processes, should be observed before use. If the saw’s sump is contaminated, the sawing operation will leave contamination on the material being processed. The residue will contain the contamination and it will be carried to the next operation. This will contaminate the sump of the next machine. Care should be taken to break the "cascade of contamination."