Adhesive Recommendation - Plastic To Metal

[DPM]

I need to glue a reducing bushing into the back side of a Swiss CNC collet. The collet is made of alloy steel and the bushing is made from plastic. I'm having a hard time finding an adhesive that will hold the bushing in place.
I've tried gorilla glue and super glue with no luck.
The bushing is initially held in place with a slight interference fit, but ultimately will rely on an adhesive to stay in place.
The bushing is split to allow compression and expansion as the collet is open and closed.
Bushing material can be either Nylon 6/6 or Delrin/Acetal.
The adhesive must be oil resistant.
The collets have 3 slots so the contact surfaces can be relatively small.
For example: OD of bushing = .110 ID of bushing = .070 OAL = .600

Looking for proven recommendations. Thanks in advance.

 

[PeteM]

I'd start by considering Delrin as the harder-to-bond material - not that nylon is easy. Might be that an epoxy meant for plastic (it has a bit of flex) would work with nylon if you rough the surfaces and have them scrupulously clean.

Not sure what it's worth to you to have this split bushing stay in place, but it seems that having a small recess ground into the back of the collet to hold it might be a help.

 

[sfriedberg]

Loctite Black Max 380 together with Loctite SF 770/7701 primer on the plastic side to overcome the low surface energy (hard to glue) nature of the Nylon or Delrin. Fully degrease the collet, too.

 

[TeachMePlease]

You don't glue them. You make two o-ring grooves and fit the proper sized o-ring so that it's a press fit in the back of the bushing.

Or you pay KEB/Hardinge/Southwick to press in a meehanite/brass/nylon bushing and they make it a few thou oversized and bored inline with the collet bore.

Or you make it a slight press fit for the ID of the bushing, but this is the least preferable option.

Glue is not the right choice here.

 

[Rick Finsta]

I've used Locktite AA330 with SF7387 activator in similar applications, but agree with TeachMePlease that there is probably a better solution here, especially given the rpm involved in a lot of Swiss work.

 

[Terry Keeley]

Plastic Bonder Syringe - Tan | J-B Weld

This worked for me on some ABS to steel.

 

[DDoug]

Supposedly "Fusor" it the go to for hard to bond.

 

[Labrat]

I need to glue a reducing bushing into the back side of a Swiss CNC collet. The collet is made of alloy steel and the bushing is made from plastic. I'm having a hard time finding an adhesive that will hold the bushing in place.
I've tried gorilla glue and super glue with no luck.
The bushing is initially held in place with a slight interference fit, but ultimately will rely on an adhesive to stay in place.
The bushing is split to allow compression and expansion as the collet is open and closed.
Bushing material can be either Nylon 6/6 or Delrin/Acetal.
The adhesive must be oil resistant.
The collets have 3 slots so the contact surfaces can be relatively small.
For example: OD of bushing = .110 ID of bushing = .070 OAL = .600

Looking for proven recommendations. Thanks in advance.

In this application you will need a specific bond line thickness, so the interference fit is out unless you just use 10% of your surface area for the interference fit and 90% for the adhesive.
I would recommend 3M DP8005 for plastic to metal, but not for nylon or delrin. Could you use ABS?

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjV05Szi7XvAhXvEVkFHXJxBIgQFjAAegQIAxAD&url=https%3A%2F%2Fmultimedia.3m.com%2Fmws%2Fmedia%2F79749O%2F3m-scotch-weld-structural-plastic-adhesive-dp-8005.pdf&usg=AOvVaw3cjNBwVSXRRe68wc1UM661

I agree with TeachMePlease. If this was my project, I would be looking hard for some other way than glue.


EDIT:
It just occurred to me: Take the middle 80% of the interface area and cut a 100tpi thread into the plastic and a few splines for anti-rotation, then bond them in. When the adhesive bonds to the metal collet, you will have your mechanical capture.

 

[DPM]

Thanks for the responses so far. Here's a few images to paint a better picture of what I'm working with. This is a pickoff collet and the part will be held in it after it's cut off. The bushing has to be slotted or in this case given a spiral cut to allow flexing for opening and closing of the collet. A solid bushing will not allow the collet to close. The purpose of the bushing is to give the part a surface to rest on when the collet opens and the ejector pin pushes it out. The slots on the bushing can't be bigger than the part dia because this can cause the part to tilt in to the slot and get jammed up when the ejector comes in.

 

[Jim Williams]

If I am seeing this right, the shoulder in the collet keeps the bushing from coming out the front of the collet. How about putting a snap ring behind the bushing to hold it loosely against the shoulder. I do not think trying to hold the bushing in with an adhesive is going to work because the bushing moves around as it flexes.

 

[pavt]

Liquid Nails construction adhesive. No kidding, have you ever tried to get that stuff apart? I had a situation at work where somebody tossed out some liquid nails in the bin, and some plastic scrap on top. Had to use the torch to separate them. Never did get all the adhesive out of the bin.

 

[TeachMePlease]

A: Unless you're doing something I've never seen done with the part in the pickoff: The bushing does not need to flex. The bushing ID should be a couple thou bigger than the part OD, and that's it. Solid bushing.

B: You make the bushing as a press fit (with o-rings) in the back of the collet, with a .125"Ø nose that goes inside your .129"Ø up to just shy of the 1/16"Ø land. This prevents interference of the bushing and the collet, and prevents you from needing a split/spiral groove bushing.

C: This all assumes you're using a custom knockout pin that has the length necessary to travel the length of the .129"Ø bore and push the 1/16"Ø part out the front of your sub collet.

 

[DPM]

Liquid Nails construction adhesive. No kidding, have you ever tried to get that stuff apart? I had a situation at work where somebody tossed out some liquid nails in the bin, and some plastic scrap on top. Had to use the torch to separate them. Never did get all the adhesive out of the bin.

I like the liquid nails idea. Simple and makes sense. That stuff is made to bond just about anything. Just not sure about oil resistance but worth giving a shot. Thanks for the idea and thanks to everyone else for your input.

 

[R. Dan]

I've had some luck with Barrel Bond, which is an adhesive the penturners use.
Packard Woodworks: The Woodturner's Source: Barrel Bond Pen Epoxy

It looks like it is still available online but apparently has been discontinued by System 3.

 

[pavt]

I like the liquid nails idea. Simple and makes sense. That stuff is made to bond just about anything. Just not sure about oil resistance but worth giving a shot. Thanks for the idea and thanks to everyone else for your input.

As long as your parts are very clean first and let it set overnight, it's oil resistant. Actually it seems to resist everything. Not sure what dissolves it, maybe MEK ?