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I am trying to join steel with methacrylate, I have tried a glue that adheres to different materials, like 3m DP8405, but the adhesion is very poor, I have tried to use an acrylic epoxy like Weld-on 42, I cover the whole screw, encapsulating in a single piece inside the methacrylate, are there more alternatives for gluing metal with acrylic?

Thank you!!!!!!!!!!!!!!!!!!!


First of all, look at the failure surfaces. If there is fracture of the adhesive then your adhesive may not be strong enough. However I suspect that you are seeing failures at the interfaces between the adhesive and methacrylate and between the adhesive and the stainless steel.

Next recognise that adhesive bonds depend upon chemical bonds to provide interfacial strength. There needs to be some reaction between the adhesive and the methacrylate, so selection of another adhesive may help.

But for the stainless you will need something more than just a spit and wipe to prepare the surface. You need to get the surface chemically active by etching or grit blasting. If you want longer term bond strength then you may need to treat the surface of the stainless to prevent hydration. See Link




What exactly are you trying to do? If you want a fastener (stud) protruding from a sheet of acrylic, then just gluing a screw into a drilled hole is unlikely to work as well as some of the alternatives, due to the relatively small area of acrylic you have to resist whatever mechanical loads are coming from the screw. All of improvements work by increasing the area of acrylic that participates in the joint:

- tap the hole and then install the screw, with some loctite adhesive to help it stay put (primer on the s.s. fastener will help the loctite achieve higher bond strength)
- add a nut and washer on the opposite side of the acrylic sheet and apply a small torque.
- use one of a seemingly infinite variety of plastic inserts like: https://www.mcmaster.com/inserts-for-plastics, then install a stud or set screw of the desired length with loctite adhesive to hold it.




The screw I need to encapsulate for an aquarium, I have improved the technique so that bubbles do not appear, I have made a piece in PET and filled with Weld-On 42 that when curing forms a union with the methacrylate by material fusion ,,, glue does not make any union with the stainless steel but encapsulates it and is blocked by the fusion of the methacrylate ... I understand that this is the best way or is there an alternative?

Thank you!!!!


Degreasing the Stainless Steel and then priming with a Silane Coupling agent would increase the bond between the adhesive & the stainless steel. A Silane won't do anything for acrylic to acrylic bonds since the coupling mechanism is organic to inorganic. Tapping and threading the "plexiglass" as btrueblood suggested would seem like a vast improvement. Finally, if you were to machine a piece of plexiglass, similar to the piece of PET, so you could both "pot" the bolt & you could "Solvent-Weld" the potted bolt with Acetone.

1) Mill PMMA potting part.
2) Tap Plexigrass (PMMA)sheet.
3) Prime bolt with Silane and let dry.
4) Assemble - potting part & bolt (without glue).
5) Thread through Plexiglass but not tight.
6) With Eye Dropper drip acetone around threads. You should easily see some penetration, if the threads are not to tight.
7) With Eye Dropper drip acetone around the potted part. You should easily see some penetration.
8) Let it sit overnight.
9) Using your glue, pot the bolt.

The Acetone will temporarily dissolve the PMMA and as the Acetone off gasses, it will fuse the two PMMA parts together.
Acetone evaporates too quickly to puddle on a surface & melt the PMMA, you need to trap it between two surface.


With regard to epoxybot's comments, please realise that silanes are only effective if the metallic surface is chemically active. Painting it on to a "clean" surface is insufficient to enable adequate chemical bonds to occur. You must remove existing hard oxides from the metal such that the silane can react. A LIGHT grit blast may be the best method. Do not solvent clean after abrasion, that only contaminates the entire surface with solvent. Blow the dust off with clean air.

You may also need to select a silane that is PMMA compatible.

The issue of metal treatment is often badly understood. It is a chemical process and long term bond strength depends on the resistance of the interface to hydration of the metal oxide in service. The surface must be clean to enable reactions to occur. The surface must be chemically active to enable reactions to occur. The surface of the metal must be treated to prevent hydration in later service, hence the silane application. To reiterate, it is not sufficient to just clean the metal and apply the silane. Make it chemically active first.

I'd probably recommend a light blast of the PMMA where the adhesive will sit to make that chemically active as well. Apart from that I'd follow Epoxybot's procedures.



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