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I'm working on a design that uses fairly large plastic components (ABS, ~400mm longest dimensions). I'm looking at adding a steel component that encapsulates this plastic part. And, the steel part needs to be tight against the ABS part.

Because of the thermal properties of ABS, the plastic part will change size fairly drastically relative to the Steel part. Since the steel part needs to tightly encapsulate the ABS part, I've been considering cooling the ABS part to around -10 to -20 Celsius before attaching the steel which would be at around +20 Celsius.

My question is, with ABS cooled to that temperature would riveting the steel part to it still be an option, or should I expect fracturing from the rivet? I've tried looking into the hardness, brittleness, and Younges modulus of ABS as a function of temperature but I can't find any good data.

Rivet would be a 7/32 sized rivet through a 3mm thick piece of ABS.

Any help would be greatly appreciated.

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Cooling ABS to -20 C should be within its operating conditions.

But why are you concerned that your encapsulation does not sit tight? What is the temperature range in which this part is used? If its above room temperature, that ABS part will expand more and most likely „press-fit“ into the encapsulation.

Do you have a drawing of that ABS part and encapsulation?

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  • $\begingroup$ This is somewhat of a retrofit solution. The temperature range for the use case is 10-40 degrees positive C. By having the steel under light tension from the expansion of the abs the end product will look slightly cleaner (hopefully) . Manufacturing tolerances and fit clearances are the main driving factor for going in this direction. I'll be able to get a tighter fit while still having sloppy tolerances. $\endgroup$
    – Diesel
    Commented Nov 11, 2017 at 0:02

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