Stamped metal washers measure typically 0.005 to 0.250 in. thick, with outside diameters to 5 in. Metalforming companies stamp them on presses from 5 to 200 tons from sheetmetal blanks fed manually or automatically, or often from coil stock on progressive dies. Press lines may include automatic uncoiling, feeding and injection systems.
Washers can be stamped from any punchable materials, including spring steel, carbon steel, stainless steel, brass and aluminum alloys. Washer designs include wavy, bowed and slotted. Typical styles include fender washers (light, medium and heavy), high-strength structural washers, U-bolt washers, split-lock styles, dock washers and automotive body shims. Order quantities typically start at 100 pieces, although many suppliers will satisfy special requests for smaller quantities.
Value-added services offered by washer manufacturers include flat or tumble deburring, heattreating and plating (cadmium, phosphate, mechanical galvanizing and hot-dip galvanizing).
Dies and stamps
Die, any of several types of tools used for the shaping of solid materials, especially those employed in the pressworking of cold metals.
Coin-Stamping Die Dies are tools used to shape solid materials, especially metals. A coin-stamping die is shown here. In coining, metal is stamped on each side with dies, which bear a reverse image of the pattern to be formed on the finished coin.Adam Woolfitt/Woodfin Camp and Associates, Inc.
In presswork, dies are used in pairs. The smaller die, or punch, fits inside the larger die, called the matrix or, simply, die. The metal to be formed, usually a sheet or precut blank, is placed over the matrix on the press bed. The punch is mounted on the press ram and is forced down by hydraulic or mechanical pressure.
A number of different forms of dies are employed for different operations. The simplest are piercing dies, used for punching holes in the blank. Blanking dies are employed to stamp out special shapes of sheet metal for later operations. Bending and folding dies are designed to make single or compound bends in the blank. Hollow, cupped shapes are formed by drawing dies; if the hollow is deep, redrawing dies are often employed in a second operation. To produce a reduced section on a hollow part, such as the neck of a rifle cartridge, special reducing dies are used. When a finished part must have a bulge at the bottom or in the middle, hydraulic dies are usually employed. In these the punch is replaced by a ram that forces oil or water into the part under pressure, thus forcing the metal outward against the matrix. Curling dies form a curved edge, or flange, on a hollow part. A special kind of curling die called a wiring die is used to form a wired edge in which the outside edges of the metal are tightly wound around a wire that is inserted for strength. A combination die is designed to perform more than one of the above operations in one stroke of the press; a progressive die permits successive forming operations with the same die.
In coining, metal is forced to flow into two matching dies, each of which bears a reverse intaglio of the relief pattern to be formed on the finished coin or part. See Mint (coin).