Return-Path: Sender: (Marvin Kaye) To: lml Date: Wed, 10 Sep 2003 11:15:00 -0400 Message-ID: X-Original-Return-Path: Received: from remt25.cluster1.charter.net ([209.225.8.35] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2574818 for lml@lancaironline.net; Wed, 10 Sep 2003 11:09:40 -0400 Received: from [68.186.243.158] (HELO erics1200mhz) by remt25.cluster1.charter.net (CommuniGate Pro SMTP 4.0.6) with SMTP id 153752398 for lml@lancaironline.net; Wed, 10 Sep 2003 11:09:39 -0400 X-Original-Message-ID: <005a01c377ae$3e2c2080$0300a8c0@erics1200mhz> From: "Eric M. Jones" X-Original-To: "Lancair Mailing List" Subject: Epoxy Bonding of Aluminum X-Original-Date: Wed, 10 Sep 2003 11:13:55 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004D_01C3778C.9F76DDC0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_004D_01C3778C.9F76DDC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Whew...somebody is writing lots of fancy procedures! In my experience = all of them are pointless beyond just three things: 1) Surface oxidation should be removed. Aluminum etchants do nicely, = sandpaper does well too as does scrubbing with scouring powders. Bon-Ami = is great.=20 2) Grease is the enemy of a good bond. You can vapor degrease with = tri-chlor or stick the part in a cathode vacuum etcher or bombard the = surface with anti-protons---but a little elbow grease and a clean = solvent does 99.99% as well. If it is safe to do, flaming the surface = with a propane torch just moments before bonding would be a fine touch = to drive off any surface condensation.=20 3) The biggest error in bonding is inadequate bond-line thickness. Epoxy = does not penetrate well. If you squeeze out all the epoxy in the bond = interface you might as well be using spittle for all the good it will = do. Remember that wherever the parts touch each other--there is no = adhesive! Be careful with clamping! Heat helps epoxy bonding tremendously. Bake it if you can.=20 Recently I used some 25-year-old epoxy putty sticks for a non-critical = application. Ten seconds in the microwave and they worked like new. I am = inclined to ignore expiration dates. For critical applications you will = have to decide, but then I am not comfortable with adhesive bonds used = in life-critical applications at all. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net "The man who carries a cat by the tail learns something that can be learned in no other way." --Mark Twain ------=_NextPart_000_004D_01C3778C.9F76DDC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Whew...somebody is writing lots of = fancy=20 procedures!  In my experience all of them are pointless = beyond just=20 three things:
 
1) Surface oxidation should be removed. = Aluminum=20 etchants do nicely, sandpaper does well too as does scrubbing with = scouring=20 powders. Bon-Ami is great. 
 
2) Grease is the enemy of a good bond. = You can=20 vapor degrease with tri-chlor or stick the part in a cathode vacuum = etcher or=20 bombard the surface with anti-protons---but a little elbow grease and a = clean=20 solvent does 99.99% as well. If it is safe to do, flaming the = surface with=20 a propane torch just moments before bonding would be a fine touch to = drive off=20 any surface condensation.
 
3) The biggest error in bonding is = inadequate=20 bond-line thickness. Epoxy does not penetrate well. If you squeeze out=20 all the epoxy in the bond interface = you might as=20 well be using spittle for all the good it will do. Remember that = wherever the=20 parts touch each other--there is no adhesive! Be careful with=20 clamping!
 
Heat helps epoxy = bonding tremendously. Bake it=20 if you can.
 
Recently I used some 25-year-old = epoxy putty=20 sticks for a non-critical application. Ten seconds in the microwave and = they=20 worked like new. I am inclined to ignore expiration dates. For = critical=20 applications you will have to decide, but then I am not comfortable = with adhesive bonds used in life-critical applications at=20 all.
 
Regards,
Eric M. Jones
www.PerihelionDesign.com
= 113=20 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) = 764-2072
Email:=20 emjones@charter.net
 
"The man who carries a cat by the=20 tail
 learns something that can be learned
 in no other=20 way."
 --Mark Twain
 
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