Cleaning Alumninum pre-TIG

admin

I've got a stack of brackets here that I'll be welding onto intercoolers and I'd like to make sure that i'm prepping them as well as possible prior to welding (the first one wasn't disastrous, but wasn't optimal).  The brackets are .5" thick x 1" wide x 2.5" long 6061 and have helicoils in the two threaded holes in them.  Unfortunately they weren't cleaned after the tapping cycle and have tapping oil in them which oozes out when they heat up.  Ideally I'd like to clean them with something that will prep the aluminum as well as eat away the oil deposits, but I can't have anything that is going to destroy the helicoils. Thoughts?  Independent of this I'm curious what you all like to use to clean aluminum prior to welding, as well as what works well for cleaning stainless prior to welding.  I've got my set of wire brushes that are dedicated for aluminum and another set for stainless, and I did that this time around, but I think my main problem was the oil residue.Jason
Reply:I might run them through the dish washer, this would add heat and get the oils out. Then before welding I would warm them up with a propane torch 200f and brush the weld zone with a new clean stainless steel brush, I would do the same to the inner-cooler as well (the heat and brush) The heating  helps the brush brake through the oxide on the aluminum.Finally I would wipe the weld area with acetone or alcohol, then weld.
Reply:Solvent type liquid penetrant cleaner/remover works well too.  You probably can't get it any more but 1,1,1-trichloroethane, old cleaner/remover,  was the best.A lot of times I will just run the arc over the joint a few times to warm it up and wire brush it.  Unless you trying to weld over the source of the oil the cleaning action of the arc should take care of it.JohnLast edited by Eyesolator; 10-14-2009 at 06:32 PM.
Reply:Wash them with any kind of oil degreaser soap and rinse thoroughly.  Wire brush it to break the oxidation layer.  If you still think it's dirty, wipe it with acetone or slx denatured alchohol and a clean rag.  Get rid of any lint ffrom the rag clinging to it before welding.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Unless you have an accurate laser thermometer, or Tempstik, I would not use an oxy-fuel torch to preheat aluminum. AWS D1.2 code recommends not more than 250 degress, and unless you have an accurate way to measure the temp, how will you know? The main concern here is moisture, as a byproduct of oxygen is H2o, so in essence when heated with an oxy fuel torch you run the risk of putting moisture back in to the part.  The best way to clean aluminum is to degrease it first, then wire brush it with a stainless steel hand brush, preferably a new brush that has never seen any other materials such as steel. We sell a product from LPS called Zero-Tri, it comes in a spray can, it is flammable, but will evaporate after a short time, then after your part has been degreased, hit it with a hand stainless steel brush. If you wire brush before degreasing/cleaning you are basically just moving the dirt and grime around, and you also just contaminated your wire brush.Last edited by ss42768; 10-14-2009 at 10:30 PM.
Reply:Acetone and a Stainless brush with clean rags....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks for all of the advice!  Yep, my brush is screwed now.  :-/  I do have a good laser thermometer, but I'll probably just try the other options to get the parts clean for now.  I have some carb cleaner (the 1gal bucket w/ dunk rack) - any harm in using this instead of acetone or denatured alcohol?  I need to pick those up though.  Both would work good to clean without effecting the steel helicoils in the long term.Jason
Reply:Do not use carb cleaner.  It is toxic when burned and also leaves a residue behind that may be worse than what you're trying to clean off.  Use acetone or slx denatured alchohol, or use soap and water and rinse thoroughly.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Originally Posted by EyesolatorSolvent type liquid penetrant cleaner/remover works well too.  You probably can't get it any more but 1,1,1-trichloroethane, old cleaner/remover,  was the best.A lot of times I will just run the arc over the joint a few times to warm it up and wire brush it.  Unless you trying to weld over the source of the oil the cleaning action of the arc should take care of it.John
Reply:Great info.  Thanks again!  It's amazing how many dangers lurk out there.  Jason
Reply:Originally Posted by BlueweldersNever use brake cleaner for cleaning metal to be welded,1-1-1 trichloroethane was the primary ingredient in most aerosol brake cleaners.http://www.brewracingframes.com/id75.htm
Reply:I just based my comment on this, from a MDS site"1,1,1-Trichloroethane can decompose to form hydrogen chloride gas when it comes in contact with strong caustics, strong oxidizers, or chemically active metals like zinc, sodium or potassium, or aluminum and magnesium powders. 1,1,1-Trichloroethane reacts slowly with water to form hydrochloric acid and forms trace amounts of phosgene when ignited or burned above 260ºC."I don't know what their idea of a trace is, so maybe it is safe.
Reply:Originally Posted by BlueweldersI just based my comment on this, from a MDS site"1,1,1-Trichloroethane can decompose to form hydrogen chloride gas when it comes in contact with strong caustics, strong oxidizers, or chemically active metals like zinc, sodium or potassium, or aluminum and magnesium powders. 1,1,1-Trichloroethane reacts slowly with water to form hydrochloric acid and forms trace amounts of phosgene when ignited or burned above 260ºC."I don't know what their idea of a trace is, so maybe it is safe.
Reply:Originally Posted by ss42768Unless you have an accurate laser thermometer, or Tempstik, I would not use an oxy-fuel torch to preheat aluminum. AWS D1.2 code recommends not more than 250 degress, and unless you have an accurate way to measure the temp, how will you know? The main concern here is moisture, as a byproduct of oxygen is H2o, so in essence when heated with an oxy fuel torch you run the risk of putting moisture back in to the part.  The best way to clean aluminum is to degrease it first, then wire brush it with a stainless steel hand brush, preferably a new brush that has never seen any other materials such as steel. We sell a product from LPS called Zero-Tri, it comes in a spray can, it is flammable, but will evaporate after a short time, then after your part has been degreased, hit it with a hand stainless steel brush. If you wire brush before degreasing/cleaning you are basically just moving the dirt and grime around, and you also just contaminated your wire brush.