TRIM® TECHNICAL BULLETIN Fluid Solutions for Metalworking

Characteristics of Metalworking Fluids – Product Residue For the sake of this discussion, residue is the material left behind on the machine and work pieces after the water evaporates from the working solution. For a metal- working fluid to perform one of its key functions, provide in-process corrosion prevention, it is critical that the fluid leave a corrosion re- sistant (residue) coating. Therefore the question is not “does the fluid leave a residue” but rather “is the residue objectionable?” So once again we are forced to make a val- ue judgment based on the specifics of our manufacturing situation with the understanding that the type of residue that the fluid leaves will affect carryoff and therefore fluid usage, machine function, filtration, machine and part cleanli- A simple but effective method for checking possible residue effects is to pour ness, and grinding wheel loading 5 ml. of coolant concentrate into a petri dish and leave it exposed to the air at among other processes. room conditions for a month or more.

One of the less obvious but truly will be the effects of any oxidation. function but can “collect” chips significant issues associated with Properly formulated fluids will re- and swarf machine residues is their tendency sist oxidation virtually indefinitely. 3. Hard – this type of residue can to capture and hold chips and The test can be repeated using vari- swarf on the functional surfaces of cause issues in machine function ous types of tramp oil contamina- as it can keep limit switches, etc. the machine. When chips or swarf tion and mineral contamination. are held by the residue, these chips from functioning properly. With begin to act as “scrapers” and the Here at Master Chemical, we clas- time and exposure to air these swarf as “lapping compound” as sify the results of these residue “hard” residues tend to get they cut and grind away at ma- tests several different ways – first harder chine seals, ways, guides, wipers, by its type and then by its solubil- 4. Gummy – this type of residue etc. Yes, they are all time change ity. These classifications are, admit- can contribute to “slip - stick ” maintenance items, but there is no tedly, at least semi-subjective but issues on machines when used to help compare fluids, need to hurry their demise. 5. Crystalline – as long as the can be quite powerful. The form crystals are easily resoluble, this A simple but effective method for classifications that we use are: checking possible residue effects type of residue does not cause is to pour 5 ml. of coolant concen- 1. Fluid – the most desirable problems on most machine trate into a petri dish and leave it type of residue, particularly on types but can cause problems exposed to the air at room condi- machines that rely on splash lu- where “optical” scales are in use tions for a month or more. In gen- brication for proper functioning for machine positioning eral, the longer the exposure to air 2. Soft – this type of residue will 6. Mixed – this is typical of more the better; the more pronounced not normally affect machine highly formulated fluids where the many different chemicals 2. Run the fluid at the appropri- Notes: present in the formulation can ate concentration. You will get 1. Master Chemical’s “Guide to have very different residue twice as much residue if you run a Clean Shop,” which can be characteristics. As always, it is the fluid at twice the minimum downloaded from our web site important to find a residue that concentration necessary to do or obtained from an authorized will work with your machine the job efficiently. In other distributor, offers more informa- and processes. words coolant management will tion about residues and how to affect residue as it does all other remove them. The solubility classifications are: fluid functions. 2. For additional information on 1. Water – any residue that is solu- 3. Use the best possible water to this subject contact your Master ble in water will also be soluble mix the fluid. “Hard water” Chemical District Manager, in working solution. If the fluid is one of the major sources of Authorized Distributor, the is soluble in water alone it will cations that react with the fluid Tech Line (800 537-3365 North be very easily washed off with components to make water America only) or our web site working solution. insoluble residues. www.masterchemical.com 2. Working solution – ideally all 4. Remove chips and swarf from residues formed on and around the sump as these metals can a machine tool would be easily also be a source for cations. resoluble in working solution 5. Periodically “wash down” the with minimum “manual” inter- machine using working solution ference. to put working solution back 3. Solvent – using solvent to where the water has evaporat- clean machines and/or keep ed. This also reduces the need them clean, is very impractical, for makeup fluid. Doing this on increases costs and reduces the a regular basis makes it easier to probability that it will be done keep the machine clean, etc, etc. on a regular proactive basis. 6. If there are difficult residues 4. Not soluble in any of the present on the machine, lightly above alone – while some resi- spraying or brushing a compat- dues seem to only be resoluble ible surfactant on the machine with sufficient elbow grease, a surface, and allowing it to pen- fair number are partially soluble etrate before wash down, may in water or working solution be very helpful. (We recommend and another portion resoluble 10% TRIM® Whamex™ Machine in solvent. On a practical level Cleaner). these are the most disagreeable residues and the most difficult The residues that the fluid leaves to deal with. are critical to the long-term success of a fluid and just what the issues In answer to the question “What will be are very much a function of can I do about residue in my opera- fluid selection, the water it is mixed tion?” the answer is “quite a bit!” with and how it is managed. 1. Select a fluid that will produce a residue that is acceptable in your application after balancing all the other issues.

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