bonding epoxy to stainless steel

Ian_Edwards

Ian_Edwards

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Will epoxy resin bond successfully to stainless steel?

How should I prepare the stainless to optimise the bond strength between SS and an epoxy laminate?

Has anyone done this successfully? i.e. made a successful bond between SS and epoxy laminate, which has lasted several seasons?
 
I think a genuine bond will be very difficult to achieve. Sanding or grinding the surface of the steel would seem to be the best option in order to give the epoxy something to key to. In any case, you will need it very clean and very dry to get anything like a bond - apply the epoxy in a warm, low humidity environment, I would think.
 
Ian_Edwards said:
Will epoxy resin bond successfully to stainless steel?

How should I prepare the stainless to optimise the bond strength between SS and an epoxy laminate?

Has anyone done this successfully? i.e. made a successful bond between SS and epoxy laminate, which has lasted several seasons?
Click to expand...
can you cut slots into the s/s to allow the epoxy to bond with its self from both sides
 
24 grit disc then scrub the epoxy in

http://www.wessex-resins.com/westsystem/surface-preparation.html

the above might help and was told to physically work the epoxy in by a boat builder of many years standing as it helps adhesion apparently, if you want quick cure go with crestabond, i've bonded in aluminium spreading plates to my engine rails with this stuff, its pretty fierce and used it instead of epoxy as it cures rapid with no surface prep.

http://www.ecfibreglasssupplies.co.uk/p-2366-crestabond-m1-05.aspx

Au revoir

Rog
 
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I would use a CT1 type of adhesive.It'll stick tenaciously to both the steel and the laminate.I wouldn't trust the epoxy bond between the stainless and the laminate.
 
rogerball0 said:
24 grit disc then scrub the epoxy in.
Click to expand...

That is what's recommended.
'Wet sand' the stainless, using the epoxy as the 'wet' substance.
Use a filler of some sort in the epoxy to limit the shear stresses if the stainless expands differently to whatever it's epoxied to.
I.e. do not attempt to get too thin a layer of epoxy.

I have made it work 'permanently' i.e. a couple of years so far, but I've not used it for highly loaded parts.

For more strength, I have bolted fittings to a 6mm thick fibreglass sheet, then epoxied that to the moulding.
 
Thanks for the very useful tips.

Since I'm bonding to both sides of the plate, I could drill holes in the plate and fill them with either a microfiber loaded epoxy or even some glass rovings, which would tie the two sides of the plate together.

I'll also incorporate some heavy duty mechanical fastening into the design and then laminate over the top of them.

Does anyone think that coating the SS with CT1 adhesive or Crestabond M1-05 and then laminating on top would work?
 
I have to say I've never heard anyone using epoxy to bond anything to SS or seen it and I wouldn't want to try it. The only things I've seen attached to stainless are bolted and to drill the holes you Cobalt drill bits.
 
>I manage to get away with sharp & slow HSS bits

I tried that but it took so long and ate the drill bits so I had to keep using new ones. I switched to Cobalt drill bits which go through very quickly and can be used 2 to 3 times subject to the thickness of the SS. Fabricators use Cobalt drill bits.
 
KellysEye said:
>I manage to get away with sharp & slow HSS bits

I tried that but it took so long and ate the drill bits so I had to keep using new ones. I switched to Cobalt drill bits which go through very quickly and can be used 2 to 3 times subject to the thickness of the SS. Fabricators use Cobalt drill bits.
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I manage to re-sharpen my HSS bits too
 
vyv_cox said:
The toolmakers I used to work with probably worked with stainless steel more than anything else. They used HSS drills for everything, but knew how to keep them in top condition. I use cobalt on the boat because it is difficult for me to resharpen them there but HSS at home.
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Some also manage to sharpen their own (best) saw`s too
 
sailorman said:
Some also manage to sharpen their own (best) saw`s too
Click to expand...

I've given that up since buying a new one from Wickes for £5. excellent performance, at that price just not worth resharpening for the amount I use it. I did buy a chainsaw sharpener with a grindwheel recently, the blades always seemed harder than the files so I was finishing one off each time I cut a few logs.
 
I used to manufacture highly stiff optical tables using steel cores and stainless steel top and bottom skins. These structures weighed up to about 3 tonnes. Epoxy bonds extremely well to stainless steel, both 300 and 400 series steels, ie non magnetic and magnetic varieties.

The important thing is to ensure that the steel is extremely well prepared by sanding and abrading and then to ensure that the surface is perfectly clean and thoroughly degreased, cleanliness is of the utmost importance.

If it is possible to use hot cured epoxies so much the better, their shear strength is up to 8000 psi. Normal domestic cold cure epoxies run in at about 500 to 2000 psi while really good cold cure epoxies (aircraft grades) at about 4000 psi.

The bonding should be done with the items clamped together and commercial systems often have a cotton scrim to prevent the glued surfaces from contacting and squeezing out all the glue. Typical finished glue lines are about 0.1 mm thick.

While these bonds are wonderfully strong in shear, they are frail when it comes to peel strength and it is always necessary to incorporate a "peel buster" a device to withstand all the peel forces. Typically this could be some through bolting, rivetting or weldment.

The main thing to remember is proper surface treatment of the steel and the need for perfect degreasing. Any sniff of silicone will destroy everything - you can never adequately grind away or clean the surfaces if ever anything has once been contaminated.
galps
 
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galps said:
I used to manufacture highly stiff optical tables using steel cores and stainless steel top and bottom skins. These structures weighed up to about 3 tonnes. Epoxy bonds extremely well to stainless steel, both 300 and 400 series steels, ie non magnetic and magnetic varieties.
Click to expand...

Years ago I help a friend glue the broken bed of a biggish (3 foot diameter swing) lathe together with one of the Ciba 9000 series epoxies. It worked very well, and as far as I know the lathe is still in use. Mind you, broken cast iron gives a lovely rough surface for bonding to.
 
I must say I've never had much joy getting any kind of permanent bond. What's the application and which way would the loads be going? As Jumbleduck says, it's better in shear than anything else, but I still think doomed. Someone else suggested holes or slots in it to let the resin permeate. I once worked for a sports car company who had (mild) steel inserts in fibreglass. The steel would have big (2") holes in it so that the resin AND fibres could pass through and bond to each other - even if not the steel.
 
application?

The application is to bond in a 10mm SS plate which will take the thrust loads from a P60-K Python Flexible drive.

The engine is a Yamaha 4JH4E producing a maximum of about 55bhp (on a good day).

The boat weighs about 15tonnes fully loaded.

So taking a few wild guesses, if the boat stops from 5knots (~2.5m/sec) in say 30 seconds, i.e. going full astern and I've not tried to measure this but it seems about right. Using Newton's F=MA I get a load of about 250kg. This gives a rough order of magnitude of the load, it might be twice this or perhaps half.

The plate will be approximately 460mm wide and 200mm tall, a mini bulkhead if you like, and the load will be applied around about the center of the plate. I don't think much torque will be applied, just the friction from the thrust bearing, which should be small.

I intend to Epoxy the plate in with multiple layers of bi-axial glass to the hull and the longitudinals (3 sides), see the sketch, which I hope makes sense. The longitudinal are 200mm x 75mm.

I'll ensure that the GRP is ground back to sound laminate and fully cleaned with acetone before I start, I'm confident about this bit having done it successfully many times before.

I am concerned about the SS, I don't think the bond will be heavily loaded, it will effectively be pushing against a heavy fillet of epoxy glass, and I've guessed that a 10mm SS plate will not bend that much over 230mm or so, so there shouldn't be a tendency to peel.

Comments?
 
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