2004 Quarter - Wisconsin - Missing Both Clad Layers

I concur that if the OP coin weighs 5.7 grams then it is not missing the clad layers. However it came to be this color the process was PMD.

Thanks bobby for taking time to look that up. The info he gave about the Schuler monitoring thickness appears to be accurate but the info Mike Diamond gave seems to show the problem can happen also after the creation of the blanks and that is more common.

Coil thickness monitor. The coil thickness measurement device checks deviations from the correct coil thickness in on-line operation. If there are tolerance deviations, the material is advanced to a point in front of the die space, the press is stopped in TDC and the electric roll feed moves the out-of-tolerance coil through the open die to the take-up coiler. https://www.schulergroup.com/major/...chuere_e.pdf

The vast majority of missing clad layer errors are bonding errors. If insufficient tonnage is applied, or if the facing surfaces are inadequately cleaned, the clad strip fails to bond to the core strip. The loose clad layer then falls away some time after the coin blank is punched out by the blanking press.

Most times the clad layer falls off before the planchet reaches the coinage press. Every so often the clad layer separates after a coin is struck. This leaves the exposed copper core with a blurred design.

The rarest form of missing clad error is not caused by an insecure bond at all. It is a rolling error that traces back to the bonding mill. Three potential scenarios are involved:

1. The leading end of one clad strip lags behind the leading end of the core strip and the other clad strip.

2. The trailing end of one clad strip ends prematurely.

3. A large gap is present in one clad strip.

https://www.coinworld.com/news/us-c...ly-miss.html

From Schuller





I can upload here all the schuller line photos and also the Miller-Schuller, as the CNC used the Jung

Hi bobby. Reread my last reply above. Mike Diamond explained in that article most of the missing clads happen after that, so only the rarer types would be prevented by the new machine process that monitors thickness.

Not exactly, it does show that the rarest form was related to that and now would no longer happen it appears, and how it happens otherwise that continued after the new equipment so thats good to know you can still find them after those dates and why for those looking or who wanted to know.

The rarest form of missing clad error is not caused by an insecure bond at all. It is a rolling error that traces back to the bonding mill. Three potential scenarios are involved:

I would imagine that if a blank has a badly bonded clad layer, the upset mill is a strong candidate for splitting it apart. That's a tremendous amount of shearing pressure directed at a right angle to the layers.