Mint-made errors are called "type-2 blanks (or planchets)" after an upending mill adds uniform, rounded rims. Type-2 blanks may also be considered striking errors as they are prepared correctly, but are released without having been struck. A misfeed can occur when the metal strip is fed through the blanking machine. The punches sometimes overlap the leading edge of the metal producing a straight clip. Sometimes, the punches strike an area of the strip which overlaps the hole left by the previous strike producing a curved clip. Sometimes punches strike the irregular trailing edge of the metal strip producing irregular clips. Coins are
Metal zipper Metal zipper A metal zipper is a zipper, zip, zip fastener or fly with its binding edges consisting of individual pieces of metal that are molded into shape and set at regular intervals on the zipper tape. Metal zippers are mainly made of brass, nickel and aluminium, and given their durability, they are mostly used in jeans, work-wear, heavy luggage and heavy-duty garments that must withstand high strength and tough washing. The metal zipper is the oldest type of workable zipper, having been invented by Gideon Sundback as an improvement of Whitcomb Judson's "Clasp Locker" that majorly consisted of a