Chemical Etch as a pretreatment to boning

[MAC3382]

Hello, All:

I intermittently need to bond various ground metals to similiar or different metals. Sometimes the metals are soft, but usualy these metals are extremely hard and an adhesive is our only option. (Please trust me on that one.) These metals may or may not have a plating applied and they are typically no larger than a playing card.

When we bond the metals we usually need to abrade at least one mating surafce to increase the adhesion. I would really like to simplify this process and I was hoping that a safe chemical etching option existed. I have found some information on acid etching, but it looks ominous to the untrained.

Is anyone aware of a simple and safe small "batch" process to effectively roughen a bonding surface?

Thank you,

Mac

 

[MAC3382]

Yes, I meant BONDING!

 

[ScottyUK]

In the early days of printing thick film heating elements onto steel substrates for high volume applications such as kettle and water heater elements we had a similar problem. Adhesion between the steel and the thick film inks was a difficult problem to solve - at the time I bailed out of the thick film hybrids industry we were using grit blasting to mechanically roughen the surface of the stainless steel prior to coating. We also experimented with surface oxidation and had a couple of furnaces adapted to run a controlled atmosphere resulting in something other than an oxide finish. This was in pre-production trials when I left - not sure if it ever made into large scale or if it was abandoned.

And yes, 'boning' made me wonder whether to even open this thread!


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Sometimes I only open my mouth to swap feet...

 

[tomwalz]

Acid etching may not be as intimidating as it first looks. It depends on the materials.

More information, especially on the materials and the amount of surface effect desired would help.

Sanding?

Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

 

[MagMike]

If you can use an anaerobic adhesive, you wouldn't have to roughen or etch the surfaces. They work better with smooth surfaces, because there's less opportunity for air to be trapped in the bond area.

Some cyanoacrylates involve an activator that is applied to one of the surfaces immediately prior to bonding. This etches or leaves free radicals which react with the adhesive (placed on the mating surface). It is very simple to apply.

 

[MAC3382]

Hello, all:

Thank you for your responses.

When we "abrade" the surface as stated in my original post we use a variety of methods from grit blasting to a very fine sandpaper. All the adhesives we use have a better bond stregth after this process. This seams to work the same for an acrylic with an activator, epoxy, etc. I am trying to elliminate this cumbersome step of "abrading."

Typically we want to remove the "sheen" from the plating or alloy and we are not trying to remove material.

The variety of adhesives is driven by specifications by our customers.

We bond a variety of cross-sections, but the largest is the face of a playing card.

From an acid etching point of view I could start with Nickel plated products. This plating seems to give us the most trouble. We have found that a stronger bond is yielded when the activator is applied to the Nickel side of the joint.

Any acid etch suggestions or suggested reading?

Thanks,

Mac

 

[tomwalz]

Just to start at the beginning; are the parts cleaned before bonding? Is a water break, water drop or similar test run? There is a short explanation at

http://www.cs4u.org/newsletters/2006/20063March.pdf

We find that with any kind of bonding cleanliness of the parts being bonded is paramount.

We also prefer a caustic based cleaner in order to achieve saponification or a detergent based cleaner.

Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com