Recent posts on cutting fluids reminded me of this question. I once heard that machining aluminum using alcohol produces a beautiful finish that resists corrosion. In fact the rumor was that this is how the shiny solid aluminum knobs on stereos are made.
Does anyone have any experience with this or know where to find info on it?
Don't know about alcohol but there are other refrigerant type cutting fluids that will leave a very nice finish on aluminum. Downside is that untreated "shiny" aluminum isn't going to stay that way unless undisturbed, no handling. It'll have a very thin film of oxide on it. Good for telescope mirrors, not so great for knobs and hubcaps. Any home electronic aluminum trim parts I've seen have been either lacquered or anodyzed. Anodyzing isn't likely to give you a mirror finish, part of the process involves etching the surface in some rather nasty caustic chemicals to remove any oxide or other contaminants before the process starts. No shiny surface from that. So it's likely your knobs are either lacquered or clear powdercoated.
One problem with using alcohol would be that you'd end up with flammable vapor in your workshop. One spark and you'd be baked. Other aluminum cutting fluids may give you liver cancer but they won't blow you up!
I hesitate to post this, as there is some danger involved, not so much to the machinist as to the people around him, but trichloroethelene and carbon tetrachloride work well for machining aluminum. These are nonflammable but toxic, (carbon tetrachloride more so than trichloroethelene). These fumes are heavy and may build up to dangerous concentrations at floor level thus presenting a danger to small children or pets [birds very succiptible]. These can also get sucked into a living space from a workshop.
These will defat your skin and cause problems if you are not careful.
Never the less, both liquids work very well as coolants on aluminum, and are available in many areas in pint containers at the hardware store. A small quantity of a good quality vegetable oil added to the carbon tet or trichloro such as olive oil will produce even better results. The old tap magic seems to have been a mixture of trichloro and a light oil.
Good luck and let the group know how you make out.
Greetings George, Have you used trichlor on aluminum? Because I have and it's not pretty. Trichlor attacks aluminum. If you wipe with a wet rag it keeps coming away black from the aluminum being eaten off. And tapped holes will corrode badly. Eric
Really? What areas would those be? I haven't seen trichloroethylene at retail sale for several years -- and I haven't seen carbon tet on a retail shelf since some time in the 1970s. If you know of a place in the U.S. where either can be purchased retail *now*, I'd love to know about it.
One shop I worked in used denatured in a spray bottle for 1/4" and smaller endmills cutting pockets with carbide. For cooling though, not cutting. Spray misters created too much local weather. :) Another benefit is chip clearing - no sticky coolant holding the chips. my 2 cents
Hi when I started metalwork in the 70s the apprentices job was to wash down
soot and oil from sections of profiles.There was a old oildrum in the backyard with a sheetmetal lid on, filled with trichloroethelene -"tri" it was called and a common thing to use. No fire hazard, and it can solve incredible amounts of oil and grease. It leaves the skin white and dry. Somehow everybody knew it´s not the proper way to do it, but it worked well. I´m glad those days are gone! What stopped the use was this interesting effect: put tri near the bright light of your welders arc, and it develops Phosgen.That´s a WW1 chemical weapon and you dont want it in your workshop. Many years later Tri got restricted to heavily monitored closed systhems for de-greasing in powdercoating etc Saying the stuff works well sounds like advocating the use of mercury in silver-plating (or making hats) mad as a hatter ed wolf
I think tri chlor getting in the water table might have had some impact on how it is not restricted. We are just getting approval to remove the carbon filtration units from our facility that have been treating ground water for many years.
Tap Magic hasn't been the same since the removal though.
-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
It does that going through the gas fired oven in the lab. trailer, makes a cigarette taste like shit, this effect lasts for about eight hours - nearly enough to make you quit smoking! I'm probably lucky to have survived. Also works great as a paint stripper.
I was mainly interested in the alleged claim that alcohol as a cutting fluid will leave an aluminum surface resistant to corrosion. I am an optical engineer and am always looking for manufacturing techniques that may be useful for ultra-precise optical mounts and assemblies. There are times when anodize is not an ideal surface finish for such things.
In any case it seems like if there is any truth to this rumor, it is not common process. I may have to try the experiment myself.
Tap Magic used to contain 1.1.1 trichloroethane, not 1.1.1 trichlorethylene. The latter is also known as perchloroethylene or dry cleaning fluid. This is still available as Carbosolv at my local hardware store. I have a couple of gallons of trichloroethane stashed away to be used sparingly for things that require it. KPR thinner is one use.........Paul
============== Just received an email from someone what been there and done that, a regular reader that can no longer post. Thanks for the straight skinny.
--------- email follows ---------- George,
I am unable to post to RCM due to a problem with my ISP. I can read, just not post.
You have it wrong. Trichloroethylene is not the solvent used for machining. What you're thinking of is 1,1,1, trichloroethane-----which was the active ingredient in Tap Magic and other tapping solutions at one time. They were NOT recommended for aluminum, nor should they be used on aluminum. It requires a different formulation to avoid corrosion.
I am very familiar with the use of the chloroethane I mentioned. It used to be used in the sumps of our turret lathes along with cutting oil when I worked at Sperry.