Looking for ways of joining metal and plastic

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Discussion Overview

The discussion revolves around methods for permanently joining plastic parts with metal components, focusing on various techniques suitable for both DIY and industrial applications. Participants explore different approaches, including heat stacking, mechanical fasteners, and adhesives.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using heat stacking as a method to join a plastic handle to a metal body and inquires about other permanent methods.
  • Another participant describes various techniques, including using weld-nuts with machine screws, deformable hooks or latches, and sheet metal barbs that can be inserted into the plastic.
  • There is a question about the type of metal involved, with stainless steel and aluminum mentioned as possibilities.
  • Concerns are raised about the difficulty of repairing a specific mug handle, with suggestions for alternative approaches like creating new metal rings or handles.
  • Some participants express skepticism about the feasibility of reattaching an old plastic handle, citing issues with plastic brittleness over time.
  • A participant clarifies that their inquiry is about hybrid assemblies in general, using the handle as an example.
  • Another participant mentions the possibility of using thermoplastic welding and questions whether it is the same as heat stacking.
  • Suggestions include using a countersunk screw with glue for joining, and the potential use of industrial adhesives like Methyl Methacrylate for bonding plastic and metal.
  • There are discussions about whether the methods should be suitable for industrial applications or if DIY solutions are acceptable.

Areas of Agreement / Disagreement

Participants express a range of opinions on the best methods for joining plastic and metal, with no clear consensus on a single approach. Some advocate for mechanical fasteners, while others suggest adhesives or welding techniques. The discussion remains unresolved regarding the most effective method.

Contextual Notes

Limitations include the lack of specific details about the types of plastic and metal involved, as well as the conditions under which the joints will be used. There are also unresolved questions about the effectiveness of different joining methods in various applications.

Chandrasekar
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TL;DR
How to join a plastic part with a metal part?
i have a plastic handle and want to join it with a metal body. i can join it with heat stacking method i have find a product who done done that.
is there any other way to join permenently?

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I have usually seen either weld-nuts on the metal part with machine screws going thru and holding the handle, or making the plastic part slightly deformable with 'hooks' or 'latches' that fit in cutouts in the metal.

There are also instances of having sheet metal barbs that insert into the plastic. Depending on the ultimate use, the barb may be either molded into the plastic of merely inserted into a preformed slot in the plastic.

For do-it-yourself, I have not been able to to get a reliable connection by thermoplastic welding the plastic onto the metal.

Please let us know what you come up with.

Cheers,
Tom
 
Chandrasekar said:
i have a plastic handle and want to join it with a metal body.
What sort of metal is it, stainless steel or maybe aluminium ?
 
Chandrasekar said:
i have a plastic handle and want to join it with a metal body.
Are we talking about that mug (?) on the picture?

Based on the picture there should be some metal pieces in the handle and originally it was a metal-metal connection, maybe done with spot welding.

I don't think this can be repaired easily (and, what's more omportant: it won't be any sturdier than before).
What I would do ... well, honestly, I would just buy a clay mug, but to use that one on the picture I see two ways:
- to make two rings of metal strap attached to the old handle and make the mug sit in the rings
- make a complete new handle&rings entirely from some steel wire

Something like these, but more 'engineer way':
shopping
 
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Rive said:
I don't think this can be repaired easily (and, what's more important: it won't be any sturdier than before).
Very true.
Do not waste time reattaching an old plastic handle to a metal container.
Plastic becomes brittle with time, it then fails at a progressively lower stress.
Replace the handle with new, or with an improved material.
 
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sorry guys, i think i have not given proper question.
it is just a example to understand what i want. what i really want is a way to join a plastic part with a metal part (a hybrid assembly - i think).

Thank you for your concerns.
 
Last edited:
Chandrasekar said:
TL;DR Summary: How to join a plastic part with a metal part?

i have a plastic handle and want to join it with a metal body. i can join it with heat stacking method i have find a product who done done that.
is there any other way to join permanently?

View attachment 323028
this picture is given as an example explain to what i really want.

'I just want a any other method to join a plastic part with a metal part.'
i got two way to join
1. Heat Stacking
2. fasteners
is there any other way?
 
Tom.G said:
For do-it-yourself, I have not been able to to get a reliable connection by thermoplastic welding the plastic onto the metal.
Thermoplastic welding and heat stacking are same?
 
Spot weld a short, flat headed countersunk screw to the metal.
Mould or drill a hole in the plastic to slide over the screw.
Place some glue in the hole, then press them together.
 
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  • #10
Chandrasekar said:
is there any other way?
Are you looking for something what can be industrialized (like that handle from the picture), or just DIY level will do?

For the letter, as I recall there are some glues which can bond on plastic and metal too. But I would keep those only for places without much stress of any kind.
Synthetic resins (even with some fibers added) may be also do the trick (not just used like a glue but as means of extra mechanical support).
 
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  • #11
Rive said:
Are you looking for something what can be industrialized (like that handle from the picture), or just DIY level will do?
for industrialized level
 
  • #12
Chandrasekar said:
for industrialized level
Yeah, go with a mechanical fastener. Personally, I'd say threaded rod welded to the body, and nuts to hold the handle on.
 
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  • #13
I just did a post on bonding metals with epoxy. Search "Methyl Methacrylate adhesives" There are formulas that are mix compatible with metals and plastic. And their bond is outstanding.
 
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