Some bonding advice


David A Froble
 

I'm back playing with my learning project. Got a question.

I have a piece of 1.125 dia anodized aluminum tubing, which will be bonded
into a composite structure. I'm worried about the bond breaking loose,
and the tubing turning in the structure.

I don't know if my concern is valid. Perhaps the bond will be strong enough.

I have considered some type of pins in the tubing, AN3 bolts for example, to aid
the bonding. Should I worry about this? If using the bolts, is there any better
way to position them. I also worry that the fiberglass will just fit over the end
of the bolts, and not really get a good bond.

Any advice?

--
David Froble Tel: 724-529-0450
Dave Froble Enterprises, Inc. E-Mail: davef@...
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA 15486


Keith Spreuer
 

It depends on the loads applied to the tube. In many cases the bonds is enough with good surface prep. Next step up is to drill dimples and coat with flox. then bolts as you suggest. Or bolts drilled after cure is the max


On Mon, Oct 18, 2021, 8:53 PM David A Froble <davef@...> wrote:
I'm back playing with my learning project.  Got a question.

I have a piece of 1.125 dia anodized aluminum tubing, which will be bonded
into a composite structure.  I'm worried about the bond breaking loose,
and the tubing turning in the structure.

I don't know if my concern is valid.  Perhaps the bond will be strong enough.

I have considered some type of pins in the tubing, AN3 bolts for example, to aid
the bonding.  Should I worry about this?  If using the bolts, is there any better
way to position them.  I also worry that the fiberglass will just fit over the end
of the bolts, and not really get a good bond.

Any advice?

--
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef@...
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486






Jim Parrish
 

Depending on what this tube will be doing?  If it is going to be moving something...Aileron, elevator..it needs to have a bolt(bolts) or pin going thru it...
The process i use anytime putting any aluminum parts bonding in epoxy or glass structure, is to wet sand the surface to be glued with my epoxy mix and leave the surface wet with this and continue the layup...due not just put it in dry.. Jim


A R Goldman
 

In the back of my increasingly narrowing mind, I seem to remember a specific type of annodizing that created an appropriate bond with epoxy.

Rich (still slogging along to finish my aerocanard-- if only I would stop deviating from the straight and narrow)


-----Original Message-----
From: Jim Parrish <parrishairx1@...>
To: members@canardzone.groups.io
Sent: Tue, Oct 19, 2021 9:20 am
Subject: Re: [Canard Zone] Some bonding advice

Depending on what this tube will be doing?  If it is going to be moving something...Aileron, elevator..it needs to have a bolt(bolts) or pin going thru it...
The process i use anytime putting any aluminum parts bonding in epoxy or glass structure, is to wet sand the surface to be glued with my epoxy mix and leave the surface wet with this and continue the layup...due not just put it in dry.. Jim


JOHN STEICHEN
 

Don’t confuse anodize with alodine. You don’t want anodized aluminum parts. Also you can use low profile cherry max if this is your elevators

On Tue, Oct 19, 2021 at 9:28 AM Keith Spreuer <kspreuer@...> wrote:
It depends on the loads applied to the tube. In many cases the bonds is enough with good surface prep. Next step up is to drill dimples and coat with flox. then bolts as you suggest. Or bolts drilled after cure is the max

On Mon, Oct 18, 2021, 8:53 PM David A Froble <davef@...> wrote:
I'm back playing with my learning project.  Got a question.

I have a piece of 1.125 dia anodized aluminum tubing, which will be bonded
into a composite structure.  I'm worried about the bond breaking loose,
and the tubing turning in the structure.

I don't know if my concern is valid.  Perhaps the bond will be strong enough.

I have considered some type of pins in the tubing, AN3 bolts for example, to aid
the bonding.  Should I worry about this?  If using the bolts, is there any better
way to position them.  I also worry that the fiberglass will just fit over the end
of the bolts, and not really get a good bond.

Any advice?

--
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef@...
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486






James Russell
 

Hi Rich:

I think you're thinking of PAA - phosphoric acid anodizing + a CIAP (corrosion inhibiting adhesive primer) like Cytec BR 127. After running your part thru the PAA etch line, very quickly you need to prime it with the CIAP, cure it (@ 250 F), then you can bond at your leisure. At Bell, we had an 1 year life (for bonding) after priming.

No other methods will guarantee against disbonds over time.

Find an etch line facility local to you, make friends with someone there, and have them run your part thru much cheaper - as you don't need certs.
However, I have been looking at 3M Surface Pre-treatment AC-130 - it compares favorably to PAA for crack growth AND you can get a 50 ml kit for $65 at SkyGeek. It requires just a water break clean part & you apply it by brush. I've attached a TDS.

BR-127 requires refrigeration and I haven't found it smaller than 1 qt. + the dry ice & temp recorder & HAZMAT charges make shipping stratospheric.

! qt. will last me forever... I've attached an TDS.

But, 3M has EW-5000AS CIAP, with RT storage/shipping and 1 qt. packaging, still 205F cure - but no chromium. Still HAZMAT shipping... See attached TDS.

I took apart used control rods & found corrosion inside.  Our airplanes will last alot longer than we think & corrosion never sleeps.

If you can't afford to spend the weight for steel for your part, make friends at a bond shop & have them etch & prime your part - it's probably cheaper than DIY.

I'm a hard head & since I'm prepping all the bonded parts on the Cozy, I'm biting the bullet.

One angle I follow is to buy expired materials (from bond shops & repair places) - the actual storage life of most aircraft materials is far longer than the expiration dates - so if you pay them a pittance (tell it's for your aluminum boat!), they avoid HAZMAT disposal fees and you get good materials.

My $00.02.

Regards,
James

PS: The CIAP works great for non-bonded parts as well...


Greg Norman
 

David,
Without going into the details of the properties of anodized aluminum vs non-anodized bonding, I can tell you my unscientific garage applications of both show the same result with MGS epoxy and glass - no joy. Aluminum to laminate epoxy bond sucks.
Like the plans show in many places make dents, holes, and yes-rivets, bolts, extrusions to prevent rotation.

Greg Nornan

On Mon, Oct 18, 2021, 11:53 PM David A Froble <davef@...> wrote:
I'm back playing with my learning project.  Got a question.

I have a piece of 1.125 dia anodized aluminum tubing, which will be bonded
into a composite structure.  I'm worried about the bond breaking loose,
and the tubing turning in the structure.

I don't know if my concern is valid.  Perhaps the bond will be strong enough.

I have considered some type of pins in the tubing, AN3 bolts for example, to aid
the bonding.  Should I worry about this?  If using the bolts, is there any better
way to position them.  I also worry that the fiberglass will just fit over the end
of the bolts, and not really get a good bond.

Any advice?

--
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef@...
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486