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<p>[QUOTE="SuperDave, post: 2821097, member: 1892"]A planchet is punched under circumstances which don't allow much metal movement - if you visualize it, you'll see that pressure is essentially equal across all points of the blank being punched whether the punch is a hollow cylinder or the solid cylinder actually used. </p><p><br /></p><p>At the moment of strike, though, one must contemplate the planchet metal more in terms of fluid dynamics than solid. Dies are not consistent in relief and a lot of planchet metal needs to move relatively significant distances to fill the "voids" in the die deeper than the original planchet thickness. The Mint leverages these concepts of liquid dynamics to make it possible. </p><p><br /></p><p>I've always thought that your second idea is the basic explanation for Blakesley Effect - metal is moving, like a liquid, towards the path of least resistance (in this case the blank space left by the clip) and the planned migration of planchet metal towards the opposite side lessens, leading to a weaker strike opposite the void.</p><p><br /></p><p>It's intuitive, however, that slight differences in die alignment and clip location relative to the die (is there in the design more need, or less, for metal to flow in that specific direction?) can have a bearing on how pronounced the Blakesley Effect is, or even if it appears at all.[/QUOTE]</p><p><br /></p>
[QUOTE="SuperDave, post: 2821097, member: 1892"]A planchet is punched under circumstances which don't allow much metal movement - if you visualize it, you'll see that pressure is essentially equal across all points of the blank being punched whether the punch is a hollow cylinder or the solid cylinder actually used. At the moment of strike, though, one must contemplate the planchet metal more in terms of fluid dynamics than solid. Dies are not consistent in relief and a lot of planchet metal needs to move relatively significant distances to fill the "voids" in the die deeper than the original planchet thickness. The Mint leverages these concepts of liquid dynamics to make it possible. I've always thought that your second idea is the basic explanation for Blakesley Effect - metal is moving, like a liquid, towards the path of least resistance (in this case the blank space left by the clip) and the planned migration of planchet metal towards the opposite side lessens, leading to a weaker strike opposite the void. It's intuitive, however, that slight differences in die alignment and clip location relative to the die (is there in the design more need, or less, for metal to flow in that specific direction?) can have a bearing on how pronounced the Blakesley Effect is, or even if it appears at all.[/QUOTE]
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