Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Permanent Bond of these two items

Permanent Bond of these two items

Permanent Bond of these two items


I want to permanently bond a metal plate to a plastic box. I don't know details of the materials, but I have provided images here that hopefully will give those in the know enough for a good guess.

The box will hang from the mounting plate when used in a stage performance environment. I will try to treat it kindly, but it will unavoidable take some abuse. I would like to bond to be as strong as the plastic box itself. I would use screws, but because of the way the electronics are mounted in the box, this is not practical.

The plate is 5" x 2". The area on top of the box between the two ridges that define the flat top portion is about 6.5".

I have some J-B Kwik Weld, but I figure I have only one shot at this so I had better seek expert opinions first.

RE: Permanent Bond of these two items

And The second image (hopefully)

RE: Permanent Bond of these two items

Unfortunately the answer depends heavily on the materials used for these items. From the pictures, I would guess ABS, which means your JB Kwik Weld probably would work fine. Make sure you clean the surfaces prior to bonding, preferably with a fast evaporating solvent like acetone. If the housing is polypropylene (PP), then it will be extremely difficult to get a good bond with any adhesive. Good luck.

RE: Permanent Bond of these two items

Is there any test I can reasonably do on the plastic case to determine its composition. From what I've read I assume the issue is HSE vs. LSE material. Is there any easy at-home test for determining which I've got?

Is part of the adhesion issue that that same layer of adhesive has to bond to both surfaces? I guess I'm asking if a VHB double sided tape like 3M 5952 would give me a better shot at strong permanent bond?

RE: Permanent Bond of these two items

There is also 3M 4298 Adhesion Promoter - which I can get in a small amount from Amazon here: Link

Would this help given that I don't know the composition of the plastic? I think the metal plate is powder coated aluminum, but I'm not even 100% sure of that. Would the adhesion promoter help with J-B weld type adhesive or only with the VHB tape? How about J-B Plastic Weld? Would that not work on the metal plate?

RE: Permanent Bond of these two items

I think you will be better off with the VHB tape, if it does fail the failure will be a slow peel. The JB weld failure will be more sudden.

You are judged not by what you know, but by what you can do.

RE: Permanent Bond of these two items

Given two rigid adherends, VHB is less likely to fail by slow peel than by short term cleavage. My experience says it _will_ fail, within a year, with no useful warning.

I personally would use VHB, only to provide fixturing while an adhesive like 3M #5200 or an unfilled RTV silicone cures to full strength.

Mike Halloran
Pembroke Pines, FL, USA

RE: Permanent Bond of these two items

And just for fun, I'd run a couple of big-ass ty-raps around the outside of the assembly, and cinch 'em up real nice.

Mike Halloran
Pembroke Pines, FL, USA

RE: Permanent Bond of these two items


Are you sure the housing does not have a recycling code on it that identifies the polymer? You can call the manufacturer to ask about the material. There are some do-it-yourself polymer identification tests, but you would need to remove a piece of the housing and the tests are destructive.

You are correct that surface energy is an important factor. The adhesion promoter would be helpful for either the bulk JB epoxy or the tape adhesives assuming the plastic housing has low surface energy. I think your plastic housing likely is not low surface energy, so the epoxy probably should work fine.

RE: Permanent Bond of these two items

This material gives a pretty good bond to most of the bondable plastics given adequate surface preparation. Not much use on polypropylene, but then very little is. I came across it from the marine industry and have used in a few applications where I absolutely do not want joint failure. So far I'm happy. So far... winky smile

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close