Part X. Wastebasket and Composite Categories

Embedded Debris

Scraped-In Debris

Definition: There are many entry points in the minting process during which foreign matter can end up embedded in a planchet or coin.  The rarest type of embedded debris (1 known case) is scraped-in debris.  Here foreign matter is left embedded in a blank or planchet when the disc is scraped against a debris field.  The embedded object or objects persist through all subsequent steps in the minting process

This 2002-P Indian quarter dollar was struck on a heavily damaged blank or planchet.  Despite the excruciatingly severe damage, the coin still ended up in a Mint Set.  Both faces of the planchet show deep scratches.  On the reverse face, a particularly wide, deep gouge terminates in a piece of black debris.  The width of this particle precisely matches the trailing groove, proving that the particle’s movement across the face of the planchet was responsible for the groove.

The planchet also shows matching, shallow, C-shaped depressions on the left side of both faces a short distance in from the rim.  They represent crushing damage.  These ill-defined depressions thinned the planchet in this area, which is why the peripheral letters did not strike up completely.

Part V. Planchet Errors:

Pre-Strike Damage:

Scraped-In Debris

Definition: There are many entry points in the minting process during which foreign matter can end up embedded in a planchet or coin.  The rarest type of embedded debris (1 known case) is scraped-in debris.  Here foreign matter is left embedded in a blank or planchet when the disc is scraped against a debris field.  The embedded object or objects persist through all subsequent steps in the minting process

This 2002-P Indian quarter dollar was struck on a heavily damaged blank or planchet.  Despite the excruciatingly severe damage, the coin still ended up in a Mint Set.  Both faces of the planchet show deep scratches.  On the reverse face, a particularly wide, deep gouge terminates in a piece of black debris.  The width of this particle precisely matches the trailing groove, proving that the particle’s movement across the face of the planchet was responsible for the groove.

The planchet also shows matching, shallow, C-shaped depressions on the left side of both faces a short distance in from the rim.  They represent crushing damage.  These ill-defined depressions thinned the planchet in this area, which is why the peripheral letters did not strike up completely.

Part VI. Striking Errors:

Impact-Induced Warping

Definition: A well-accepted principal holds that any part of a coin or planchet that remains between the dies throughout the strike should be flat on both faces.  That makes abundant sense since both die faces are essentially flat.  There is a notable exception, though.  Sometimes, when a coin is greatly thinned by the strike, it develops a warped surface as soon as the hammer die retracts.  The face struck by the hammer die bows upward while the opposite face develops a complementary pucker.

     The buckling of the coin may be due to the heat that is generated by the strike.  Another possibility is that the coin experiences “radial springback”.  In this phenomenon, the coin metal is radially stretched by the strike, but retains some resilience.  When the pressure is lifted, the coin contracts radially, causing the thin metal to buckle.

     Impact-induced warping is most commonly seen and most severe in uniface strikes (coins struck against another planchet).  The aggregate double thickness increases the effective striking pressure and the coin’s final thickness will be half the minimum die clearance.  These two factors produce a thinner coin.

     This 1991 cent takes the form of a cupped, uniface broadstrike.  The planchet represented by this coin was struck against an underlying planchet.  Neither planchet was confined by the collar.  The center of the obverse face bulges upward while the featureless reverse face is strongly concave

Part IV: Die Errors

Die Breaks:

Cuds:

Elongate Cuds

Definition: A cud whose connection to the die’s edge is considerably narrower than its maximum width.  Elongate cuds may form at the intersection of several die cracks, when those cracks confine a long, narrow section of the die face.  A thick wedge or a thin flake may detach from the area surrounded by the die cracks.

An elongate cud can also form along a pre-existing die crack.  Die chips arranged along the die crack may enlarge and coalesce into a long, snake-like die chip that may eventually reach the edge of the die face or may connect with a pre-existing cud.

This 1994 India 5 rupee coin shows a long, narrow elongate cud on its obverse face.  A piece of the die face detached from an area surrounded by three die cracks.  The ends of one of the die cracks are still visible and intersect the rim at 9:00 to 12:00

PART IV. Die Errors

Die Cracks:

Shattered Die

Definition: A “shattered die” features numerous intersecting die cracks.  Along with the profusion of die cracks, a shattered die can also incorporate other forms of brittle fracture such as die breaks and retained die breaks.

A shattered die often indicates a terminal die state, i.e., a die just short of catastrophic failure.  A series of coins struck by a shattered die can often be arranged in a progression of increasing severity.

A network of intersecting bi-level cracks constitutes one type of shattered die. In a bi-level die crack, there is vertical displacement at the site of the crack. This means the die face has sunk in on one side of the crack.

An example of converging radial bi-level die cracks can be seen in this 2000 Indian 2 rupees coin. These bi-level die cracks meet in the center of the obverse face.

A more extensive set of bi-level die cracks can be seen below in a 1913 Chinese 100 cash coin.  The obverse face shows at least seven bi-level die cracks and a few smaller conventional die cracks. At least one crack shows characteristics of both. This is not that unusual, as you can have both horizontal spread and vertical displacement in the same location, or a transition from vertical displacement to horizontal spread as you proceed along the crack. Despite its tenuous structural integrity, this die was nowhere near terminal failure and was likely able to strike quite a few more coins in this condition.

The shattered die found on this 2007-P Roosevelt dime consists of a 50% retained cud with numerous bi-level die cracks within the body of the retained cud.  At least seven similar shattered obverse dies are known among 2007-P dimes.

This coin is in the collection of Richard Creny. Image by R. Mentzer.

The shattered die shown below has extensive evidence of brittle fracture. Many types of brittle fracture may be represented, e.g., die breaks, retained die breaks, die cracks, a split die, etc. The die may or may not be approaching catastrophic failure (see Catastrophic Die Failure). Not surprisingly, a series of coins struck by a shattered die can often be arranged in a progression of increasing severity.

Note: Two separate specimens are shown below.

The 1985 India 25 paise shown below Features a large retained cud, a small retained interior die break, and numerous die cracks, most of them bi-level. The right side of the obverse face and the corresponding left side of the reverse face are weakly struck. This is largely due to a tilted die error (vertical misalignment) of the entire obverse face. The left side of the obverse is quite strongly struck, despite the large retained cud. This should have led to a reduction in effective striking pressure. The fact that it didn’t indicates that this part of the obverse die face was tilted down, while the opposite pole was tilted up. This tilt was most likely due to a break at the base of the die or through the shaft of the die – a break that allowed the die to tilt down strongly toward one pole.

The 2002 Brazilian 10 centavos shown below expresses various forms of brittle fracture.  There are three cuds, one retained interior die break, and a tracery of intersecting die cracks of both the conventional and the bi-level type.

The 1975 cent shown displays an early-stage counterbrockage of the obverse design on the obverse face. It was produced when an obverse die cap with a brockage of the obverse design on the reverse face struck a succession of planchets, this being one of them.

Machine parts above collar can impede expanding

coins

By Mike Diamond | May 21, 2011 10:00 a.m.
Article first published in 2011-05-30, Expert Advice section of Coin World

An off-center cent with a “sideneck strike.” Driven toward the northeast by the expanding die-struck portion of the coin, the unstruck edge collided with the side of the adjacent hammer die neck.

Images by Mike Diamond.

As a coin is struck, its expansion is abruptly halted by the surrounding collar.

When the collar fails to deploy, a coin expands in all directions. As a result, all off-center strikes and broadstrikes are wider than a normal coin, to varying degrees.

On some occasions a coin’s expansion is impeded, and the edge damaged, by machine parts positioned above the collar plate.

The most familiar obstacle to unfettered expansion is the neck of an adjacent hammer die. In a dual or quad Bliss press (the last of which was retired in 2005), the close proximity of adjacent die pairs results in the occasional production of a “sideneck strike,” also referred to as an “almost saddle strike” or a “one-die saddle strike.”

A typical example is shown here in an off-center Lincoln cent. At the pole opposite the 1 o’clock position of the obverse face, we see a deep, concave notch and an associated pressure ridge. The planchet represented by this coin lay partly within one striking chamber and almost managed to encroach on the adjacent striking chamber. In other words, the coin fell just short of becoming a “saddle strike.” When struck, the expanding die-struck area pushed the unstruck portion toward the adjacent striking chamber. It collided with the side of the hammer (obverse) die neck as the latter was striking its own coin.

Sideneck strikes are always concave and always closest to the adjacent striking chamber. In most years, this chamber would lie along a line drawn from the 1 o’clock position in Lincoln cents, or the 11 o’clock position in Jefferson 5-cent coins and Roosevelt dimes.

Strike-related edge damage of another kind is seen in an undated Jefferson 5-cent coin. The pole opposite the off-center strike has a flat, vertically oriented contact facet. It appears that the facet was produced when the unstruck portion of the planchet was pushed south by the expanding die-struck area and collided with a machine part. Another possibility is that the coin was hit while momentarily immobilized by the two dies.

In either case, we can’t be sure what machine part was responsible, although I suspect a feeder finger. I’ve encountered these flat facets on quite a few off-center and double-struck cents and 5-cent coins. In each case, the strike is about 70 percent off-center and the contact facet lies opposite the base of the bust.

The introduction of the Schuler press introduced new types of strike-related edge damage. This press uses a single die pair, with the reverse die operating as the hammer die. The damage is primarily associated with multi-struck coins. A representative example is provided by a quadruple-struck 5-cent coin. The first strike was normal. The other strikes were delivered about 20 percent off-center and are closely spaced. Edge damage is present on both the right and left sides. The contact facet on the right side is convex, slightly beveled, and extends from 12 o’clock to 2:30.

The dies evidently struck whatever machine part rested against the coin. On the left side the coin buckled when it collided with a hard object. The contact facet here is quite compact and lies next to the w of we. It’s possible that the coin was pushed laterally into an obstruction by expansion produced by the off-center strikes. It’s also possible that an object hit the coin as the latter was temporarily immobilized between the dies.

This type of edge damage can be found on numerous multi-struck cents, 5-cent coins, and Washington quarter dollars struck by Schuler presses. The pattern is consistent, although the long facet and the short facet can be located on either the right or the left side.

The affected coins all show a sequence of strikes involving a normal (or at least centered) first strike, and one or more closely spaced off-center strikes. Coins in which the off-center strikes are widely spaced or erratically positioned typically do not show this edge damage. The long facet that hugs the edge of the off-center strikes is almost certainly caused by contact with a feeder finger. I’m not sure about the short facet.

Coin World’s Collectors’ Clearinghouse department does not accept coins or other items for examination without prior permission from News Editor William T. Gibbs. Materials sent to Clearinghouse without prior permission will be returned unexamined. Please address all Clearinghouse inquiries to cweditor@coinworld.com or to (800) 673-8311, Ext. 172

http://www.coinworld.com/articles/machine-parts-above-collar-can-impede-expandi/

Copyright 2012 by Amos Hobby Publishing Inc. Reposted by permission from the March 22, 2012, issue of Coin World.)

PART III. Die Installation:

Mules: 

Two anvil dies

Definition: Mules are coins struck by mismatched dies.

The 1982 Jamaica cent shown below displays the obverse design on each face. Since Jamaica is a former British colony the obverse design was probably struck by the anvil die. The U.K. and its former colonies typically use the obverse die as the anvil die.

The obverse design on the Chilean 100 pesos bi-metallic coin shown below is carried by the anvil die.  One properly installed anvil die was paired with a second anvil die acting as the hammer die. Only one example of this mule is currently known.

The images below show a 1 EURO cent — country of origin and date unknown — that was struck with two reverse (anvil) dies.

Images are courtesy of Heritage Auctions.

A blank is a metal disc that has been gang punched from a metal strip. This metal disc or blank is commonly referred to as a Type I planchet.

This dime blank bypassed the upset mill and was therefore never transformed into a planchet.  The edge is rough, with the “cut-and-tear” texture typical of a blank.  One face of the blank has a slightly downturned perimeter.  This is from the bottom side of the coin metal strip.  The slight downwarping of the blank’s perimeter is produced when the disc is forced through a hole in a perforated base plate.

A planchet is a blank that has been through the upset milling machine. This disc of metal is referred to as a Type II planchet.

This dime planchet shows the upset proto-rim that is produced as the coin is rolled and squeezed within the upset mill.  The edge is smoothed out during its passage.  In vertical cross-section, the edge has the shape of a low trapezoid.  In other words it has sloping sides that meet a flat apex.