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What exactly is "cutting fluid" and how does it work

Discussion in 'The Tool Shed' started by SCOOBYDANNN, May 4, 2007.

  1. SCOOBYDANNN

    SCOOBYDANNN 1/2 ton status

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    I know, a newbie ? but seriously. I use it all the time and and it really does keep cutting tools sharper longer. I'm sure it keeps it cool, but what makes it get the spirals instead of shavings.:confused:
     
  2. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    a sharper, smoother cut will produce the "spirals" you speak of, also if you cut slower and use cutting fluid, you will get cleaner holes
     
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    I think its the tool cutting head , and tool speed would be the biggest factors over spirals versus shavings :dunno:

    Sharper bits at the right speed cut , and duller bits at the wrong speed do more grinding .

    Learned my lesson hanging my bumpers . I can now drill holes with a 18v drill in frame without any drama using good bits and lube .
     
  4. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    yep, drilled 1/2" plate steel and a XJ unibody with my 18v drill, slow and steady with pb blaster
     
  5. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Heat is what (mainly) kills the edge on cutting tools, cutting fluid lubricates the cutting edge and keeps it relatively cool. That spiral of metal coming off whatever you are cutting is rubbing right over the top edge of the cutting tool, without fluid, thats straight metal-on-metal friction, which generates a lot of heat.
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    There are 2 features of interest. Lubrication and cooling.

    Lubrication helps you make the cut by allowing the material to slide more easily of the "rake". This makes it tend to roll rather than being so prone to break, so you get a slightly different chip shape. It also tends to keep the edge sharper by helping it pierce and slide into the material with less abrading away of the edge. Lubrication also reduces the tendency of some materials to "weld" onto the cutting edge. For instance, using HSS bits in some grades of Aluminum.

    Coolant keeps the material from reaching a state where it's physical characteristics are weaker. For instance, carbon steel showing blue oxide has gotten hot enough to weaken the material and cause it to fail rapidly, as well as annealing it so that resharpening is more difficult (if even possible).

    Both also help keep the cutters cleaner. The lubricant by making it easier for the chip to fall out, and the coolant by flushing it away.

    Lubricants (such as those typically referred to as "cutting fluids") provide some cooling, but tend not to cool well. Coolants provide some lubrication, but tend not to lubricate well. There are various options for straddling that fence. But most tools we would use benefit more from lubrication with only moderate cooling being necessary. This occurs mostly through vaporization of the lubricant as can be seen by "smoke" when drilling a hole while using "cutting fluid". "Coolant" is usually applied as a "flood" and not normally of interest to automotive hobbyists...

    Within the typical "cutting fluids" we would use are quite a selection. I use a glycerin (soap basically) based lubricant for most drilling in steel where I will be painting it later because it's easier to clean/prep. I use WD40 for drilling/cutting/tapping aluminum. TapMagic Gold or Dark Sulfer Cutting Oil (Gunk brand specifically) for cutting steel. And I have a wax stick that I use on my band saw. It's made specifically to help the chips clear and keep the blade running smooth with minimal mess. And I've got other stuff for more specific uses, but I've probably already exceeded everyone's interest in that topic.
     
  7. SCOOBYDANNN

    SCOOBYDANNN 1/2 ton status

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    Russ---whenever you reply to something I have to get my head straight before I read:D ---that makes sence and what I needed to know---

    I do have another ?

    when using cuting fluid and welding is it necessary to clean the residue---I try to but sometimes im impatient and just start welding---unimprotant stuff really--whats best to clean up. I typically use TapMagic.

    what is a good glycerin type fluid?

    thanks

    Dan
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Define "necessary". ;)

    Obviously you can weld without cleaning, but it will be less than ideal. The results will vary depending on what lubricant you're using, and which process you are using. Excessive porosity is often the most obvious effect.

    So in general, yes, you need to clean it. The question is, "How much?"

    If we are talking about MIG/GMAW, then for non-critical stuff, particularly heavy wall, I usually just wipe it off good with a fairly clean rag. As long as the metal is shiny and "clean", that's usually good enough. For better quality/critical results, I wipe down with Acetone or Lacquer thinner, drying the residue with a clean rag rather than allowing evaporation.

    For flux-core/FCAW or Stick/SMAW, wiping off is generally good enough because the flux will float out all but the most excessive of the contaminates. I've made strong repairs with SMAW on rusty greasy stuff, thought the results were no very pretty.

    For TIG/GTAW, everything must be unbelievably clean and free of contaminates. For some materials more than others...

    For O/A or other gas welding, it depends on the materials (welding/brazing/soldering as well as base material), use of flux, and other factors.

    Note that this is also one of the reasons I sometimes use glycerin based lubricant. Simply rinsing and wiping/blowing dry results in a clean oil-free part for painting or welding. Enco sells "ready to use" purple stuff for something like $8 a gallon. Combine that with some other stuff (Dark sulfer cutting oil?) and a "Free shipping on $50 or more" coupon and your good to go.
     
  9. surpip

    surpip 1 ton status

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    speaking of welding and paint
    some of the older "anti spatter" sprays have silicone in them, and will be almost impossible to clean before painting, if you don't clean it all off, you will get "fish eyes" in your paint.
     
  10. TeamRedneck

    TeamRedneck Registered Member

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    Working on a farm, we use ag diesel for cutting fluid. Works like a dream :).
     
  11. mofugly13

    mofugly13 1 ton bucket of rust Premium Member

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    Deisel fuel, or kerosene, is the recommended fluid for machining aluminum.
     
  12. TeamRedneck

    TeamRedneck Registered Member

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    Sometimes a little of the cutting fluid finds its way to the fuel tank on my dodge ;)
     
  13. k204dr

    k204dr 1/2 ton status

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    my dad and I always uses atf. works great, and bits actually seem to get sharper. go figure.
     

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