Patent ID: 9447515
Filing Date: 2016-09-20
CPC Classification: A44C,C25D,G07D,Y10T

Claim Text:
1. A method of producing circulation coins having different electromagnetic signatures (EMS) and having approximately identical mass and exterior dimensions, the method comprising: selecting first and second steel cores having approximately identical mass and exterior dimensions; electroplating a first layer of nickel on the first steel core; electroplating a first layer of copper over the first layer of nickel on the first steel core, the first layer of copper having a thickness of at least 4 μm, to produce a first coin having a first EMS defined by a first range of conductivity values; electroplating a second layer of nickel on the second steel core; electroplating a second layer of copper over the second layer of nickel on the second steel core, the second layer of copper having a thickness of at most 24 μm, to produce a second coin having a second EMS defined by a second range of conductivity values that is distinct or non-overlapping with the first range of conductivity values, each of the first and second ranges comprising plus or minus 17% difference of International Annealed Copper Standard (IACS), and the second coin having a mass that is at most 0.01 grams more than the first coin.