Terminology
Abbreviations, symbols, and glossary
Glossary of frequently used terminology, abbreviations and symbols used in the wire drawing industry.

Abbreviations

CCA Copper clad aluminum
CCS Copper clad steel
MCD Monocrystalline diamond (=SSCD)
ND Natural diamond
MD Monodie (=SSCD)
PCD Polycrystalline diamond
SCD Single crystal diamond (can be ND or SSCD)
SMCD Synthetic monocrystalline diamond (=SSCD)
SSCD Synthetic single crystal diamond
TC Tungsten carbide
WC Tungsten Carbide (=TC)

Symbols

A% wire area reduction percentage
E% wire elongation percentage
L wire length
m wire mass
Ø diameter
Øin incoming wire diameter
Øout drawn wire diameter (= drawing die diameter)
V wire volume
α reduction cone angle (full angle)
Δ delta factor
ρ wire density
R electrical resistance
ρ electrical resistivity

Glossary

A

accuracy. (1) The agreement or correspondence between an experimentally determined value and an accepted reference value, or, in some cases, the average value obtained by applying the test method to all the sampling units in a lot or batch. (2) How close a calculation or reading of an instrument approaches the value of the calculated or measured quantity. Compare with precision. Learn more here>

angle. See preferred term reduction angle.

annealing. The simple definition in wire drawing is that annealing is a heat treatment that restores the elasticity to work hardened metals increasing the softness or ductility of the metal and decreasing the hardness. This is done to allow the metal to be further redrawn without breaking or to meet customer property specifications for the finished product. These properties are usually expressed as the percent the wire can be stretched or elongated before it breaks. Learn more here>

B

back relief. The back relief enables the wire to exit freely from the bearing, avoiding contact with any sharp edge that could scratch the wire.

bearing. The bearing area determines the wire surface quality and the wire diameter. The length of the bearing (L) is usually about 20% to 50% of the nominal wire diameter (Ø). However, this percentage varies depending on the wire material, drawing process, and on the specifications of the wire to be drawn.

bearing length. See bearing.

bell cone. See preferred term entrance cone.

blank. Also called nib, insert, or stone in the case of natural diamond. An ultra-hard material encased inside a stainless-steel (mild steel for TC) casing. The blank, with an interior geometry matched to the wire material being drawn, is the part of a wire drawing die that touches the wire. For that reason, the blank material typically is diamond (natural, synthetic, or polycrystalline) or tungsten carbide. See PCD, SSCD, ND, TC.

brittle fracture. Separation of a wire accompanied by little or no macroscopic plastic deformation. Typically, brittle fracture can be prevented by annealing the wire before drawing. Learn more here>

C

carbide die. See preferred term TC die.

capstan. The revolving cylinder part of a wiredrawing machine around which wire is rapped so it can be pulled through a wire drawing die. The surface of a capstan that the wire touches is usually made of a hard wear resistant material like ceramic or tungsten carbide.

casing. The stainless-steel outside of a drawing die that holds the ultra-hard blank (also called nib, insert or stone). The size (outer diameter and thickness) of the die casing depends on the die holder size in the machine.

contact point. See wire contact point.

course wire. This wire diameter classification differs between ferrous and non-ferrous wires. Ferrous: .630 - .16535” (16 – 4.2mm). Non-ferrous: .472/.315 - .1378/.05906” (12/8 - 3.5/1.5mm). Compare to medium wire, fine wire, finest wire and super-fine wire.

cup-and-cone fracture (cup fracture). A mixed-mode fracture, of a ductile material, where the central portion undergoes plane-strain fracture and the surrounding region undergoes plane-stress fracture. One of the mating fracture surfaces looks like a miniature cup and the other fracture surface looks like a miniature cone. Cup-and-cone fractures can be minimized by using wire drawing dies with optimal reduction angles, resulting in homogeneous deformation

D

DC die. Diamond Coated dies are tungsten carbide dies that have their inner profile coated with diamond. The inner diamond coating consists of nano-sized diamond particles. These types of dies are usually used as a cost-effective alternative to larger PCD dies in bunching and stranding applications where the wire forces are much lower than in wire drawing applications. In bunching and stranding applications DC dies typically maintain their bearing diameter much better than TC dies. The failure mode of DC dies is sudden when its coating wears off. Learn more about diamond coated stranding dies here>

deformation. A change in the form of a wire or rod. Measured in units of length. This applies to both round and shaped products.

delta factor. The delta factor is a value that is calculated from the wire area reduction and the reduction cone angle. According to industry standards and practice the delta factor should be between 1.5 and 3. A delta factor larger than 3 can increase the likelihood of cup-cone fractures. See also homogeneous deformation.

die angle. See preferred term reduction angle.

die draft. See preferred term size sequence.

die set. Die set is the term used to describe multiple die strings all having the same size sequence. A die set describes the dies required for a multi-wire (two or more strings) drawing machine. A single die string is also sometimes referred to as a set. Learn more about Esteves drawing die strings and sets here>

die wizard. See drawing die wizard.

drawing die. See wire drawing die.

draw ring. The wire begins its reduction and elongation in the reduction angle of the die. At that point the wire is in contact with the surface of the diamond and a wear ring is created over time. This drawing ring gets deeper and wider as more wire is drawn through the die. The appearance of the drawing ring may change due to the material drawn and the length of time that the die is used.

drawing die wizard. Free Windows application to configure and visualize a drawing die in 2D and 3D. Learn more about Drawing Die Wizard here>

E

eddie. See eddie wire solutions.

eddie wire solutions. Free software application to calculate wire sizes, size sequences, and production volume. Learn more about Eddie Wire Solutions here>

elastic deformation. A change in wire diameter and length that is directly proportional to and in phase with an increase or decrease in applied force.

elongation. A term used to describe the amount of extension of a piece of wire when drawn. See also elongation percentage.

elongation set. See preferred term size sequence.

elongation control. Process of manually pulling wire through die string sequences die by die to check that the elongation percentage produced by each die is within specification. Dies that do not produce an in-spec elongation are either size adjusted or changed out for another die that does. The typically starting point for elongation control is .01969” (0.5mm) or below. Learn more about Esteves matched sets here>

elongation percentage. (1) The extension of a wire when drawn through a wire die. (2) The extension of a uniform section of a specimen expressed as percentage of the original gage length: where Lo is original gage length, and Lx is final gage length.

engineering strain. The average linear strain or conventional strain. In tensile testing it is calculated by dividing the change in the wire length by the original wire length.

engineering stress. The conventional stress. In tensile testing, it is calculated by dividing the breaking load applied to the wire by the original cross-sectional area of the wire.

entrance cone. The entrance cone (bell) should be sufficiently open to allow wire drawing lubricant to enter the die and flush out any particles that have been generated. The entrance cone is typically well blended to the top of the reduction angle so that there is no sharp edge at the transition. The standard entrance cone angle for a drawing die is 60 degrees.

eWizard. Free paper or pdf handbook from Esteves Group. Basically, an off-line version of this website. Download eWizard here (sign-in required)>

exit cone. The exit cone (back) is designed to strengthen the exit of the die. The exit cone keeps the metal forming area centered in the blank, improving heat transport away from the metal forming zone.

F

fine-wire. This wire diameter classification differs between ferrous and non-ferrous wires. Ferrous: .0630 - .02756” (1.6 – 0.7mm). Non-ferrous: .082677 - .0059055” (2.1 - 0.15mm). Compare to course wire, medium wire, finest wire and super-fine wire.

finest wire. This wire diameter classification differs between ferrous and non-ferrous wires. Ferrous: <.02756” (< 0.7mm). Non-ferrous: .03937 - .0019685” (1.0 - 0.05mm). Compare to course wire, medium wire, fine wire and super-fine wire.

G

grain size. See PCD grain size.

H

homogenous deformation. Term used to describe a wire drawing process where the metal flows through the die in a way that minimizes the internal stresses within the wire. Minimizing such stresses is mainly achieved by using optimal drawing die angles that are matched to the wire material alloy and the amount of elongation. Internal bursting and cup-cone breakage related issues are minimized when a wire is drawn homogeneously. Learn more about Esteves advanced engineering services here>

I

insert. See preferred term blank.

L

landing zone. See wire contact point.

M

matched set. Generally refers to a set of two or more strings that have gone through the elongation control process ensuring that the strings will run well together within a multi-wire machine minimizing the occurrence of wire breaks and increasing uptime and throughput. Learn more about Esteves matched sets here>

medium wire. This wire diameter classification differs between ferrous and non-ferrous wires. Ferrous: .16535 - .0630” (4.2 – 1.6mm). Non-ferrous: .1378 - .01575” (3.5 - 0.4mm). Compare to course wire, fine wire, finest wire and super-fine wire.

N

nano-die. See preferred term DC dies.

natural diamond die. See preferred term ND die.

ND die. ND dies are wire drawing dies with a natural diamond blank inside. Natural diamonds, abbreviated as ND, are naturally formed within the earth under very high pressure and temperature conditions. Because of its extremely rigid lattice, it can be contaminated by a few types of impurities such as boron and nitrogen. ND dies are typically available up to a hole size of .0787” (2mm). Compare with SSCD die, PCD die, and TC dieLearn more about natural diamond drawing dies here>

nib. See preferred term blank.

non-supported metal filled PCD. Polycrystalline diamond (PCD) without a tungsten carbide support ring and with a metallic binder among the diamond grains. The metal binder is a required part of the PCD manufacturing process. The binder does not act like a glue to hold the diamond particles together. Its purpose is to encourage the diamond particles to grow into each other during the extremely high pressure and temperature sintering process. The thermal expansion difference between the diamond grains and the metallic binder limits the use of these blanks to a maximum operating temperature of ~1202°F (650°C). Find non-thermally PCD blank specifications here>

O

orange peel. Surface roughening of a wire in the form of a pebble-grained pattern where a wire of unusually coarse grain is stressed beyond its elastic limit. Also known as alligator skin.

P

PCD die. PCD dies are wire drawing dies with a polycrystalline diamond blank inside. Polycrystalline diamond blanks consist of diamond grains sintered together at extremely high pressures, and temperatures. Three types of PCD dies exist: non-supported metal filled, thermally stable (non-supported), and supported blanks. Several grain sizes are available for each of these blanks. It is typically the wire die manufacturer that recommends the grainsize making it match the wire drawing process. PCD dies are typically available up to a hole size of 1.378” (35mm). Compare with  SSCD die, ND die, and TC die. Learn more about polycrystalline diamond dies here>

PCD grain size. The average size of the diamond particles within a PCD blank. These particle sizes are typically 1, 3, 5, 10, 12, 25 & 50 microns. Learn more about PCD blank specifications here>

plastic deformation. The permanent (inelastic) amount of elongation or reduction of  a wire when it is drawn beyond its elastic limit.

plastic strain. Wire size or elongation change that does not disappear after the wire is drawn. Usually accompanied by some elastic deformation.

polycrystalline diamond die. See preferred term PCD die.

precision. The closeness of agreement between the results of measurements. Standard deviation is used to describe the measurement error or amount of “imprecision”. Learn more here>

pressure die. Pressure dies are typically used in dry drawing (soap) applications where the wire surface finish is of a lower importance. Pressure dies are slightly larger than the wire being drawn and are held in a sealed holder in front of a drawing die. This additional die pressurizes the lubricant between the back of the pressure die and the entrance of the drawing die with the aim of heating and thus liquifying the dry lubricant. This liquified lubricant is then pulled through the drawing die by the wire reducing frictional forces and enabling faster wire drawing.

R

recutting. Recutting or sometimes called refurbishing or reboring of the die, removes all the defects generated by the passing of the wire through the die’s geometry. This operation gives the die a bigger diameter. The amount of the required increase in diameter depends on the wear and general condition of the die. Recutting is a complete reprocessing of the die, rebuilding a proper geometry. Learn more about Esteves refurbishing services here>

reduction percentage. (1) The difference between the original cross-sectional area of the incoming wire to the exiting wire when drawn through a wire die. Also known as reduction of area. (2) The difference between the original cross-sectional area of a tensile specimen and the smallest area at or after fracture as specified for the material undergoing testing. Also known as reduction of area.

reduction angle. The reduction cone is the area where the incoming wire is reduced. If requested, Esteves Group can optimize the reduction angle (2α) for different wire materials to ensure that the deformation takes place in a smooth, homogeneous, and controlled way. Typically, the harder the material being drawn, the narrower the reduction angle of the die. The softer the material being drawn, the wider the angle of the die. Also, the greater the reduction or elongation of the wire being drawn, the wider the angle required. As the elongation of the wire being drawn is reduced, the required reduction angle will be narrower.

repolishing. Repolishing of a die consists of removing the defects caused by wire being drawn through the reduction angle. Repolishing is possible when the drawing ring is not too deep, and the bearing area is not damaged. In other words, repolishing is possible on dies with slight wear. Learn more about Esteves refurbishing services here>

resizing. Resizing a wire drawing die consists of enlarging the hole size. depending on the required increase in diameter this can be done through either repolishing or recutting. Learn more about Esteves refurbishing services here>

rod breakdown machine. Rod breakdown machines are drawing machines used to breakdown wire rod sizes (generally 5/16”, or 8mm and larger) to smaller sizes (.0808”, or 12 AWG is common, or 2.05mm) to be redrawn to smaller sizes yet.

roller die. Roller dies are typically used to reduce large-size rods. They can be used to make round as well as shaped wire. Roller dies turn like wheels as the wire is pulled between them and is generally a slower process than wire drawing using conventional dies. They can be an alternative to drawing dies, although wire drawing dies offers much better dimensional control of the wire diameter as the wear of a drawing die only changes its cross-sectional area. Wire rolling forces can cause the gap between the rolls to change resulting in the rod or wire to change its shape. Wire forming using drawing dies allows for diameters all the way down to .00027” (7μm) and a requires lower capital equipment cost than using roller dies. Learn more here>

S

shape back. See preferred term exit cone.

size sequence. A size sequence (sometimes called draft) is a string of wire drawing dies sized to match the wire drawing slip type machine’s mechanical elongation.  In the case of zero-slip machines the size sequence ideally is designed to maintain a consistent temperature at each die step while also considering the wire alloy’s limitations for area reduction at each die step. The size sequence is used to reduce the incoming wire in several steps down to the required final diameter. Learn more about Esteves drawing die strings and sets here>

SSCD die. SSCD dies are wire drawing dies with a synthetic single crystal diamond blank inside. Also called synthetic mono crystal diamond, and also abbreviated as SMCD or MCD. SSCD blanks are man-made diamonds manufactured under controlled conditions and are free from inclusions and cracks. These tightly controlled quality aspects lead to predictable and consistent die performance. SSCD dies are typically available up to a hole size of .0840” (2.15mm). Compare with ND die, PCD die, and TC dieLearn more about synthetic single crystal diamond dies here>

stone. See preferred term blank.

strain. The unit of change in wire size due to force. Also known as nominal strain.

strain aging. The changes in yield point, tensile strength, ductility, and hardness that occur when a cold worked wire is stored for some time.

strain hardening. See work hardening.

stress. The forces that resist a change in the volume of a material that is or has been subjected to external forces. Stress is expressed in force per unit area and is calculated on the basis of the original dimensions of the cross section of the wire. Stress can be either direct (tension) or shear.

stress-strain curve. A graph in which values of stress and strain are plotted. Stress is usually plotted vertically and strain horizontally. Learn more here>

string. See preferred term size sequence.

super-fine wire. Non-ferrous wire of a size between .015748 - .0003937” (0.4 - 0.01mm). Compare to course wire, medium wire, fine wire, and finest wire.

supported PCD. Polycrystalline diamond (PCD) with a tungsten carbide support ring. The purpose of the support ring is to give the diamond extra support when drawing harder materials like Ferris wires. Supported PCD dies also have a metallic binder among the diamond grains. The metal binder is a required part of the PCD manufacturing process. The binder does not act like a glue to hold the diamond particles together. Its purpose is to encourage the diamond particles to grow into each other during the extremely high pressure and temperature sintering process. The thermal expansion difference between the diamond grains and the metallic binder limits the use of these blanks to a maximum operating temperature of ~1202°F (650°C) classifying them as non-thermally stable. Find supported PCD blank specifications here>

T

tapered set. A tapered set is a die string that is designed and manufactured to make a bull block machine run optimally by homogenizing the temperatures in each soap box. Learn more about Esteves tapered sets here>

tensile strength. In tensile testing, the ratio of maximum load to original cross-sectional area. Also known as ultimate strength. Learn more here>

tensile test. Test to determine the behavior of a wire subjected to uniaxial loading, which tends to stretch the metal. A piece of wire of known length and diameter is gripped at both ends and stretched at a slow, controlled rate until rupture occurs. Also known as tension testing. Learn more here>

TC die. TC dies are wire drawing dies with a tungsten carbide blank inside. Tungsten carbide, abbreviated as WC or TC, also called cemented carbide, hardmetal or widia, is a metal matrix composite. Tungsten carbide particles are the aggregate, and metallic cobalt serves as the matrix. It is a non-oxidizing ceramic that can withstand high temperatures while maintaining hardness comparable to corundum or sapphire. TC dies are typically available from .005” (0.127mm) and larger. Compare with PCD die, SSCD die, and ND dieLearn more about carbide dies here>

thermally stable non-supported PCD. Polycrystalline diamond (PCD) without a tungsten carbide support ring and without a metallic binder among the diamond grains. The metal binder is a required part of the PCD manufacturing process. The binder does not act like a glue to hold the diamond particles together.  Its purpose is to encourage the diamond particles to grow into each other during the extremely high pressure and temperature sintering process. After the sintering process the metal binder is removed using an acid leaching process. Removing the binder increases the PCD blanks maximum operating temperature to 562°F (850°C). Compare with non-supported metal filled and supported PCD. Find thermally-table PCD blank specifications here>

tungsten carbide die. See preferred term TC die.

U

ultimate tensile strength (UTS). The maximum tensile stress a wire can sustain without fracture, determined by dividing the maximum load by the original cross-sectional area of the wire. Also known as nominal strength or maximum strength. Learn more here>

ultra-hard insert. See preferred term blank. Learn more here>

W

wire back. See preferred term back relief.

wire contact point. The point where the wire contacts the reduction angle is very important for a successful drawing process. For most wire types the contact should take place between 1/3 to 2/3 of the reduction angle height to ensure good metal deformation. The contact point is influenced by the reduction angle, the total thickness of the diamond insert, and the diameter of the incoming wire. Taking into account these parameters, a customized die can be designed in our Drawing Die Wizard software to help you improve your drawing process. If the angle is too wide for the elongation of the wire, causing the contact point of the wire to be too close to the bearing, the die can wear out very quickly. A wear-ring first forms at the point of wire contact in the reduction angle. As the die is used, wear will slowly extend from the wear-ring to the bearing. Once the wear reaches the bearing, wire surface quality will deteriorate and the die as well as the wire will become oversized.

wire drawing die. Wire drawing dies are precision tools used to produce round or shaped wire to very tight tolerances. The deformation and elongation of wire material takes place within the profile of the wire drawing die as the wire is drawn through it. The stainless or mild steel outside (casing) of a drawing die holds an ultra-hard insert (also called blank or nib). The inner profile of a die (similar to a funnel) has five parts. The transitions between the different parts of the profile are blended to ensure a smooth connection of the different areas, reducing the generation of metallic particles (fines) during the wire drawing process. See a description of the five parts of a drawing die here>Compare wire drawing die blank types here> Learn more here>

work hardening. An increase in hardness and strength when drawing wire caused by plastic deformation at temperatures below the recrystallization range. Also known as strain hardening. Learn more here>

Y

yield point. The first stress in a material, usually less than the ultimate stress, at which a wire will deform plastically. Learn more here>

yield strength. The stress at which a wire exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is used for many metals. Learn more here>

yield stress. The stress level of highly ductile materials, such as structural steels, at which large strains take place without further increase in stress. Learn more herre>

Young’s modulus. Synonymous to modulus of elasticity. It is the ratio of tensile or compressive stresses to the resulting strain. Learn more here>

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