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Strike Varieties

By Patrick Glassford    |   Sunday, 14 February 2010

The following content comes from Patrick Glassford website which no longer exist. To keep this information available to the public and for a perpetuity reason, we reproduced it here.

Planchets are placed into large overhead vibratory feeder hoppers and move along into a feed tube where mechanical fingers pick up, at each stroke, the bottom planchet from the tube. The planchet is placed on the bottom die, which at this point has sunk within the collar. The top die, following down, strikes the blow forcing metal to flow and fill all available space, thus taking the impressions of both dies as well as any marking which may be on the inside of the collar (reeding).

The top die then rises and the bottom die follows, forcing the struck piece out of the collar. The feeding fingers advance, pushing the struck coin into a bin, and placing another planchet on to the bottom die.

After the coins have been struck, they are passed over screens designed to remove abnormal size coins and proceed directly to telling machines. These telling machines are made in tandem, that is, there are actually two units per machine. In this manner coins are counted twice, to ensure correctness. All Canadian coinage for domestic purposes is currently issued in rolls. Prior to this, coinage was shipped in bags until about 1980. For a short period of time, about 1981 to 1983, coins where shipped out in "tubs".

Feed

These varieties occur when items other than the intended planchet are carried to the dies and struck. Also includes coins that fail to eject or leave the coining chamber.

Wrong Planchet Strikes

A wrong planchet strike occurs when a planchet designed for a different purpose, or has a different metallic content, is fed into a coining press set up to strike coins from planchets of a specific nature.

How do they occur?

To help understand how this type of error may accidentally occur, a little "inside information" is useful. The following excerpt is from page 10 under "Plant and Equipment" in the 1960 Royal Canadian Mint (RCM) report:

Nine automatic press feeders were made in the shop during the year and installed on the presses.

This is the first reference of automatic press feeders made in the annual Mint reports. From page 14 under "Plant and Equipment" in the 1961 RCM report, it is revealed that:

Much time and effort has been given to material handling and the principle of automatic feeding has been applied to the marking machines as well as extended to nine coining presses. Bulk handling, storing and weighing of blanks and scissel is gradually being extended, and in the coming year should see considerable progress in this respect.

Here we see a continuation of progress made with automatic press feeders. Also important to note are the comments referring to bulk handling and storage of blanks. Perhaps the most important fact relating to wrong planchet strikes comes from page 15 under "Plant and Equipment" of the 1962 RCM report:

During the year, three twenty ton bins and one sixty ton bin were purchased and installed for bulk storage of blanks. These are being used with a number of one ton aluminum tote boxes and automatic feed hoppers, in an attempt to decrease manual labor.

These tote boxes have pallet like bottoms which enable them to be moved from one step of the minting process to the next, with the use of a fork lift truck. At one end of the box, on the side at the bottom, there is a sliding door. The interior of the box is shaped so that its contents will flow towards the sliding door, producing an effect known as gravity feed.

Given these facts it is easy to imagine the following situations:

• a tote box filled with Ten Cents planchets (for example) is used to strike coins and is emptied, however, one planchet remained. The same box is then filled with One Cent planchets and used to strike coins. This time the Ten Cents planchet, now mix with the One Cent planchets, is fed into the coining press and struck as a One Cent coin.
• a planchet found on the floor is mistakenly tossed into a tote box or directly into a press feeder, filled with planchets of a different type.
• an odd planchet remains in the automatic press feeder after the press has been reset to strike a coin requiring a different planchet.
• it is also possible for planchets to stray in the various steps of production. For example, an odd planchet left in an annealing furnace, or in one of the large drums used to clean planchets.

These strange coins are subject to the same rigorous screening as Clips, Off centre's and other Mint Errors, But, coins struck on Wrong Planchets with specifications similar to the proper planchets tend to get by easier and are unintentionally released into general circulation.

Known types can be group as:

Canadian wrong denominations

Wrong denominations are coins struck on planchets intended for a different denomination.

This category of wrong planchet strikes is still the most common. As a rule, only planchets equal or smaller than the intended planchets may be fed into coining presses and struck as coins. For example, it is unlikely for a twenty-five cents size planchet to be accidentally fed into a coining press and struck by dies set-up to strike ten cents size planchets. Within the limitations provided by this rule, there can only be sixteen possible combinations. The sixteenth possibility is a relatively new addition. Since the release of the reduced size circulating one dollar coin (The loon), it is now possible for a planchet intended for a loon one dollar coin, to be struck by fifty cents dies.

Canadian coins struck on planchets intended for foreign coinage

These coins represent a fairly new field of wrong planchet strikes, since 1917 the Royal Canadian Mint has produced planchets and coinage for more than seventy-seven countries. All coins produced to fill orders for circulating foreign coinage contracts are produced by the Ottawa and Winnipeg Mints. Both Mints are also responsible for all domestic (Canadian) coinage.

Examples

Foreign coins struck on planchets intended for Canadian coinage

These may occur more often than appearances here indicate as they are difficult to locate as they enter circulation in countries throughout the world.

Examples

Canadian coins struck by foreign mint on a foreign planchet

In 1968, the RCM contracted the US mint in Philadelphia to strike 35 million Canadian 10 Cent coins made of nickel. It appears a few clad US 10 cent planchets were accidentally struck as Canadian dimes and released into circulation in Canada.

Canadian transitional strikes

These occur when the metallic content of coinage changes. A coin struck by dies intended to strike a different alloy. Canada's most famous transitional strike is the 1944 "Tombac" five cent.

Multiple Strikes

Rotated second strike over first - A previously struck coin receives a second strike. If the coin was flipped over between strikes it is referred to as a flip-strike. Second strike off-centre - Struck coin receives a misaligned second strike. Multiple strikes - Coins showing characteristics of more than two strikes.

Overstrikes

Double Denomination - Coin struck over a coin of a different denomination.

Struck on Scrap, Chopped Scissel, Washer or Folded Edge Strike

Collar

These strikes are the result of planchets not properly seated or centered to the collar, during strike. May involve the collar stuck to the lower die. A collar can jam in the lower position, halfway or upright, causing different effects such as strike clips. (Collar position will also affect appearance of brockage related strikes).

Flanged Partial Collar & Broadstrike

Flanged partial collar - Often referred to as "Railroad Rim", these strikes are the result of a planchet not fully seated in the collar during strike. Metal not restrained by the collar spreads out, giving the edge of the coin a lip.

Broadstrike - These strikes are the result of planchets struck without the restraining collar (jammed in the down position). Maybe centred or uncentred, both obverse and reverse showing all die design.

Off Centre

Planchet not properly centred to the dies and collar during strike, leaving an unstruck portion on the coin.

Strike Clip - Curved or Elliptical

These are the result of off centred planchets (or coins on a second strike) being cut by the top die and a stiff collar in the upright position during strike. May be curved (unstruck portion) or elliptical (struck portion).

Obstructed Die

These strikes occur when something impairs the dies from imparting its full design on planchets during strike.

Brockage, Counter-Brockage & Die Cap

Result of a planchet struck thru a previously struck coin that has adhered to the die (Die Cap). Design on coin is incused on one side. May occur on either obverse or reverse.

Counter-Brockage - Coin struck thru a brockaged coin or die cap.

Die Cap - Planchet or coin that has adhered to a die, and subsequently strikes planchets, producing unifaced, brockaged or counter-brockaged strikes.

Unifaced

Unifaced - Result of a coin struck thru a blank planchet, that may or not have capped the top die. Split or Rolled thin planchets are sometimes fed to dies with another proper planchet and struck also creating this effect.

Indented

Indented - These are the result of coins struck thru planchets or coins (Partial Brockages).

Struck through Scrap, Reeding, Tape, Grease & Filled Die

Filled die - Coins struck by dies filled with grit (e.g.), giving coins a weak strike appearance.

Grease - Coins struck thru grease are probably the most common variety known and are often improperly referred to as laminations.

Scrap - Coins struck thru scrap and fragments (of caps e.g.) leave their impressions.

Tape - Struck thru tape. (Tape has been used to identify Dies)

Low pressure/Weak strike

These strikes are usually associated with die set-up. Weak strikes are uniform in the amount of design showing, including the edge.