A REVIEW OF DIE CURVATURE AT THE US MINT SYNOPSIS Throughout a significant portion of the history of coinage die design at the US Mint, the die radius (a measure of die curvature) best suited for a coin was ideally determined by the disposition of the design and the area of the coin. It appears that, in most cases the relief of the coin design artwork was the primary determining factor. Die curvature was significantly convex enough where its presence was frequently visible on a struck coin, at least just inside the rim. In more recent years, the Mint, in a persistent effort to reduce coinage costs, began to implement matching die curvatures and planchet profiles and adding an element of exponential die curvature, rather than spherical die curvature, to the die design, at least on some issues. This entailed giving the approved design of the artwork on the coin a lower profile without affecting the appearance. This results in an overall “flatter” die crown, with less stamping force being required which extends die life and reduces costs. This paper may be viewed online without downloading at this link: https://www.coincommunity.com/pdf/A-Review-of-Die-Curvature-at-the-Us-Min.pdf
