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Here is an image of a muffler of an R/C aircraft engine. It's made of aluminium alloys. What do you think about the welding technology which is used to make this muffler? I can't see any welding bead.

enter image description here

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    $\begingroup$ How do you know it was welded? Which apparent joints are you concerned with - the end caps? The small post, or the perpendicular bit of tubing? $\endgroup$ Feb 8, 2022 at 13:09
  • $\begingroup$ @CarlWitthoft Thank you for the comment. Well I'm not sure so just thought maybe it's welded. I'm talking about all the joints which are apparent in the image. $\endgroup$
    – Roh
    Feb 8, 2022 at 15:47
  • $\begingroup$ @CarlWitthoft Here are two other images that it looks have different joints(take a look at the color of the joints): milehighrc.com/images/gas/Mufflers/55_muf.jpg , chiefaircraft.com/media/catalog/product/cache/1/thumbnail/… $\endgroup$
    – Roh
    Feb 8, 2022 at 15:54

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No conventional welds are visible. It could have been made with a furnace solder. Flux and solder are placed at joints and the unit is put into a furnace and heated; the solder melts and flows into gaps by capillary action. I am not sure a solder would work well depending on the temperature the muffler reaches. A zinc aluminum solder flows at roughly 700 F but would have low strength at about 400F. Conventional engine exhaust manifolds reach 1200 F.

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  • $\begingroup$ I rather suspect an RC engine's exhaust is cooler than your quoted peak :-) . $\endgroup$ Feb 8, 2022 at 16:44
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Cheaper than soldering would be press-fitting the parts together. To do this, at the joint where the (for example) end plug goes into the muffler cylinder, the plug diameter is slightly larger than the inside diameter of the cylinder. When you smash them together with great force, they slide together to form a joint that is nearly impossible to pull apart, yet requires no screws, bolts, welding, soldering or glue to hold it together- and it is fast and cheap to perform in a factory.

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  • $\begingroup$ That would be my guess because of the limited temperature of a soldered joint. Some kind of a swage joint similar to a high pressure hose. $\endgroup$ Feb 8, 2022 at 21:44
  • $\begingroup$ While I think blacksmith37's answer is correct but you deserve an up-vote. Thank you. $\endgroup$
    – Roh
    Feb 9, 2022 at 6:39

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