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Tolerance between Aluminum and ABS Plastic

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U Offor

U Offor

Mechanical
May 18, 2018
20
Hello all,

I am working on making a bottle cap for a wine glass bottle, and for the cap, it is going to be ABS polymer. On the inside of the cap, there is a cylindrical area where the top of a cork is going to sit (the cork's top is cylindrical too). However, the top of the cork is aluminum while the part of the cork that goes into the bottle (we'll call it bottom) is made from synthetic cork.

I am trying to determine the tolerance between the aluminum and ABS (when the top of the cork is inserted into the cap) in such a way that the top of the cork stays put, so one can continuously pop the cork off the bottle and place it back on without the entirety of the cork coming out.

I am thinking an interference fit will do, but what will be the effects of such a fit when using it on two different materials, in this case, aluminum vs. ABS.

Bonus: Will an interference fit work best in this case?
 
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Is this a reusable cap? What's the utility lifetime, i.e., how long can the consumer make use of it?

Given that ABS and aluminum are dissimilar materials, I can't even imagine that the joint will hold up even once. Cork the bottle, pull up on the cap, and the cap separates from the aluminum.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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Against forum rules to post same query in multiple forums.

 
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@Ron

Apologies. I didn't know if this belonged in Materials or Mechanical so I can go close the other topic.
 
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@IRStuff

This was my worry really. If they were similar materials, then it would be a lot more feasible.

As for your other questions, yes it's a reusable cap and as far as the lifetime, I will say the typical lifetime of any wine/alcoholic/champagne bottle, so we're talking about at least 7 years.
 
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@FACS

The second link definitely helps me to think of alternatives, but the top part of the cork needs to fit into the cap, while the bottom part should fit into the bottle.
 
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I've seen these on stuff where I don't think the seal is very critical. Maybe something like off-brand irish creme or something. It's a short cork and relatively loose fit so it's a couple few pounds of force to pull it out instead of 50 or so with a long tight cork on a bottle of wine.


Imitation is the sincerest sign of flattery.
 
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Yes, but there are only two components for those, the cap and the cork, and presumably, the cork is glued to the cap.

The OP wants a 3rd material between the cap and cork, and it's metal while the cap is ABS. Interference fit, alone, isn't going to cut it. Positive fastening, or interlock, would, in my mind, be some sort of spline or indexing tab to keep the metal from rotating within the ABS, and something to keep the ABS from slipping off the metal, some sort of snap lock.

Glue would still need something to grip on the metal side, like grooves or textured surface.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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How many of these do you need to make? Is glue on the table (specifically a 2 part epoxy)?
 
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I posted in the other forum that you posted in originally but it got canned....so

Look at the thermal differences between ABS and Aluminum. Aluminum has a high coefficient of expansion and contraction. Might not be much of an issue for room temp wines but for chilled wines it might be an issue for interference fits.

 
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"Aluminum has a high coefficient of expansion and contraction."
Not nearly as high as any plastic. I guess you must be used to comparing things to steel. When comparing plastics to metal, all the metals are pretty much the same.

CTE of steel is about 7 ppm/F

Aluminum is 13

ABS is about 40
 
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How about an overmold with ridges on the aluminum part for the ABS to grab? If you didn't want to overmold, how about an acme thread or a rounded thread?
 
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@Stick
Yes, adhesives is on the table. I'll likely be making a few thousand, at minimum.

@moon161
Hmmm, the overmold/ridges idea seems good. Should the ABS also have ridges too? I took a look at the amazon link, weird that I didn't see anything like that when I was searching. Thanks.

@IRstuff
Glue/adhesives is definitely on the table and honestly, I gave up on the interference fit idea due to the reasons you mentioned.
 
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@compositepro....thanks. I was not aware that ABS was so high! I should have known since epoxies are also way up there.

 
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A few thousand pieces likely rules out my suggestion, but I'll pass it along and let you decide. I was going to throw out West Systems G/Flex epoxy since it can bond to both ABS and aluminum, but the surface prep required and having to deal with a 2 part epoxy that has a finite pot life would make me investigate other avenues first.
 
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There are a number of 3M and other companies' double sided structural tapes such as VHB that could work. Note, however, 3M makes sooo many double sided tapes, it can take a while to figure which one to use and what it's real properties are.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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uoffor said:
Hmmm, the overmold/ridges idea seems good. Should the ABS also have ridges too?
Click to expand...

Overmolding is a technique that molds plastic to a substrate that forms a part of an injection mold. The plastic would mold to the aluminum substrate that holds the cork and interlock with its contours.

 
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