An indentation hardness test employing a 136-degree diamond pointed pyramid is used as an in­denting tool on the test piece, the ratio between the force or applied load in kg. and the resulting surface area of indentation in sq mm being expressed as a pyramid hardness number (DPN). Also known as the Vickers Hardness Test.

Thin wire that has been coated with diamond particles codeposited with a nickel alloy from an electroless nickel bath. The wire is used to make small grinding pins for grinding and polishing and sintered carbide dies.

See Bichromate Dipped Finish.

A chemical treatment for magnesium alloys in a boiling sodium dichromate solution, resulting in surface film that resists corrosion.

A device used to reduce the size of wire, it consists of five sections: 1) the bell radius and entrance angle, which direct the flow of lubricant; 2) the reduction/approach angle, which is where the entire reduction-in-area and compacting of lubricant onto the incoming wire occur; 3) the bearing, which controls the final diameter of the wire to guarantee roundness, straightness and finish; 4) the back relief, a conical area that strengthens the exit of the die and prevents breakage of the nib; and 5), the exit zone. The number of dies can range from a single die to a string of 35 dies. The die material can range from tungsten carbide to natural, monocrystal and polycrystalline diamond. Most dies draw round wire but they can also be used to draw shaped wire.

The box is a metal structure located at each capstan block on a wiredrawing machine. The front chamber holds the lubricant and has the entry hole for the incoming wire. The second chamber holds the die(s) in alignment with the wire. Water-cooling is often provided in the box, which is movable for alignment adjustments to the capstan block. Guide rollers and wire break devices can be supplied on the box.

Lubricants used in a die box for the initial coating and lubricating of the product before it enters the wiredrawing machine. It can be a fluid or a paste compound.

1) The principle process for casting near-net shapes of such nonferrous metals as zinc, aluminum and zinc-aluminum alloy (see casting). 2) Adjusting the die box alignment to get the correct wire casting.

The entrance angle of a wiredrawing die shows the profile. The contour shows the approach and the reduction angle as the working portion of the die. It is the front to back shape of the die.

Adhesion buildup of metal onto the surface of the die caused by the breakdown of the lubricant film on the wire surface, resulting in metal-to-metal contact. This results in excessive friction, higher die temperatures and a rough surface in the die that results in scratches on the drawn wire.

A mounting mechanism to position the die at its proper location and orientation within the wiredrawing machine. These are universally adjustable on large diameter wire to compensate for any variation and to reduce permanent wear on the die. The holder is usually adjusted to compensate for those factors and then locked in its vertical alignment. See Die Box.

A longitudinal line or scratch formed on drawn or extruded metal parts resulting from the use of a roughened tool or the drag of a foreign particle between tool and product.

A procedure to ensure that dies perform as designed. This may include a regular replacement schedule of replacing dies before they wear out of size, the cleaning and inspection of dies and the procedures in place for re-working dies to larger diameters after they have worn over their original size.

The working part of the die that is inside the casing. Rough die nibs are produced by sintering a mixture of tungsten carbide and cobalt. For larger sizes the hole is pre-shaped in the sintering operation and finished by drilling and polishing with diamond or boron carbide abrasive or by spark erosion. See Die, Cored Nib.

The number assigned to a die for identification and cataloging purposes, usually the same number that is assigned for the same purpose to the product made from that die.

1.) The hydraulic pressure of the stock measured in the die cavity. 2.)A pressure die is used to improve lubricant uptake to enable hydrodynamic lubrication. A pressure die composed of two dies. The first die is 7% to 10% larger than the incoming wire diameter so that a narrow gap exists between the die and the incoming wire surface. The second die is the working die in which the actual reduction occurs. The gap size is very important: if it is too narrow, lubricant take-up on the wire will be reduced, preventing hydrodynamic lubrication; if it is too big, there will be no pressure build up in the working die and lubrication will be equivalent to a conventional die. See Hydrodynamic Drawing.

A combination of wiredrawing dies for a certain required reduction con­taining a number of dies of stepped diameters, preferably in a geometric series. The sets must be changed as a whole to ensure proper sizing.

The removal of the outer surface of wire rod by the use of a sharp-edged die to scalp the metal to produce a better surface.

Phrase used to describe the erosion, distortion or disfigurement of the die’s contours as it is being used to produce a product. Generally, excessive wear characteristics are created by undesirable levels of friction and fatigue that are usually compensated for by proper application of clean lubricating and cooling fluid.

Shaped dies in which sections of tungsten carbide are fitted together within a frame form. The shaped hole can be adjusted for size and shape by in­serting a set of spacers of the appropriate size between the sections and the frame, or by adjusting screws.