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<p>[QUOTE=&quot;John Burgess, post: 7491706, member: 105098&quot;]Hmmm, It&#039;s my understanding a coining die is slightly convex, it isn&#039;t concave or flat, meaning the center is the first contact point and goes outward with compression. </p><p><br /></p><p>I&#039;m no coining expert by a long shot, nor a physicist but this &quot;coin metal flows inward in the strike&quot; is counterintuitive considering the fact the die face is convex with the center of the die being the first contact point, and the coin is flattened outward to the collar die. </p><p><br /></p><p>Blanks are run through the upsetting mill to guarantee a nice rim on the coin during the strike and for no other reason. it&#039;s guaranteeing the die makes full contact in the strike on the edges because an un-upset blank may have thinner edges from the punching out of blanks. I agree with the statement that it&#039;s done to be sure there&#039;s enough metal at the rim for full contact to form a complete rim. the weakest point of contact at the end of the strike is the rim, because the die faces are convex. it done for a better finished product, same reason the die faces are slightly convex.</p><p><br /></p><p>metal under extreme pressure I believe flows wherever it can, in any direction it can only really restrained by the confines of the collar and between the die faces, there is an outward movement, and an upward and downward movement due to the recesses of the die, and I&#039;d assume also an inward movement in the flex of the 60 ton compression of the strike, there&#039;s a lot of force at play here. but as far as movement of the metal, I&#039;d say the majority of it is actually outward, because why have a collar die if there&#039;s no outward expansion?&nbsp; Why do broadstrikes get larger instead of smaller? </p><p><br /></p><p>it&#039;s very clear without a collar the metal flows outward in the strike until the strike is finished. With the collar, there still has to be an outward flow of metal, and a flow in every possible direction until there&#039;s nowhere left for the metal to go between the confines of the dies and collar. the center of struck coins aren&#039;t bowl shaped on both sides either but every die face is slightly convex, so I do not doubt that there is an inward movement, as well as other directional movements during the strike, I just don&#039;t think the inward movement is the most of the movement of metal in a strike and one of the least along with upward and downward, and outward being the most movement to rill the confines of the collar. I&#039;d think during the compression the metal moves outward due to the die faces, to the collar, then it&#039;s moving back upward, downward to fill all voids available, and pushing back against the dies because it&#039;s got nowhere else to go, because it&#039;s under great pressure to go somewhere from the strike.</p><p><br /></p><p>Don&#039;t get me wrong, I&#039;m not saying there isn&#039;t inward movement, I&#039;m saying that outward movement is a more significant movement in the strike, but&nbsp; multidirectional movement must also happen until all void space is filled and there&#039;s nowhere else left to go for the coin metal.</p><p><br /></p><p>I&#039;d also think due to compression, the inward movement would be one of the last movements to happen as the metal pushes back against the dies, the hammer die specifically which is the only &quot;moving point&quot; of the strike that could be moved, barring a collar or die failure.</p><p><br /></p><p>I think I just talked myself into this &quot;inward movement theory&quot; after all..... inward I think would be one of the last, of not the last, movement&nbsp; of struck coin metal....[/QUOTE]</p><p><br /></p>

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