Copper Conductor Technologies
Copper electrolytic tough pitch
BS EN 13602 (Cu- ETP1), BS EN 1977, ASTM B224 (C11000), BS 6926 (C101) BS 6017 (Cu-ETP2)
Copper, oxygen free
BS EN 13602, BS EN 1977, ASTM B224 (C10200) BS 6926 (C103) BS 6017 (Cu-OF)
Copper oxygen free electronic grade
ASTM B170, BS EN 1977, ASTM B224 (C10100) BS 6926 (C110) BS 6017 (Cu-OFE)
LOROM Specialty conductors & alloys:
- Cadmium Copper Alloy 162
- CS-95 (Beryllium Alloy)
- Cadmium free ‘Alloy 135
- Tinsel wire
- Thermocouple
- Litz wire
Copper Alloy Comparison
copper alloy comparison3
copper alloy comparison2
copper alloy comparison1
Tinsel wire
For application that requires extreme flexibility flex fatigue endurance and low current carrying capacity are required.
Flat metal ribbons of bronze, silver or copper alloys are spirally wrapped around a textile core of cotton, polyester and aramid etc.
Typical applications include robotics, voice coil lead wire, medical device leads and hearing aid cords.
Litz Wire
Litz conductors reduce A.C. losses in high frequency windings where operating frequency is the first consideration.
Litz cables are actually stranded film insulated conductors or stranded magnet wires, which are cabled into a geometric pattern permitting each wire to occupy every possible position in the entire length of the cable at some point.
The reason for this arrangement is to reduce losses caused by the tendency of currents to flow only on the outside surface of wires at high frequencies. The operating frequency influences the actual Litz construction and is used to determine the individual wire gauge.
Special film coatings on each individual strand are available where special requirements dictate e.g. for voltage breakdown or environmental protection.
Thermocouple Wire
A thermocouple consists of a pair of dissimilar wires joined at one end.
Selected wires with different known thermoelectric properties will produce a useful electrical signal that varies with the temperature difference in a predictable way.
Thermocouple materials are produced, tested and sold in 3 tolerance grades called standard, special & extension which are intended to ensure interchangeability of thermocouple sensors without special calibration testing reported to the user.
The usual goals in picking a thermocouple type are to provide an adequate measurement over the longest possible life and at the lowest cost.
Copper Drawing
We will take you on a brief tour of the copper-wire and copper-cable manufacturing facility of LOROM Industrial copper drawing plant in Hangzhou China
The first step in the manufacturing process takes place at rod break down. Here 15,000-pound coils of 5/16-inch (or 2 American Wire Gauge) or 8 mm copper rod sourced from the finest copper mines are reduced to copper wire.
During the wire drawing, the copper rod is pulled through a series of manufactured diamond or tungsten Carbide dies, which gradually decrease in size.
The rod and dies are flooded with a coolant and a synthetic lubricant to increase the life of the dies and keep the copper wire from overheating.
Dependent on final configuration the result is a 5000-8000-foot coil of 10-, 12-, or 14-awg copper wires.
Annealing
After wire drawing, the wire is extremely brittle and can easily be fractured if flexed. Since finished copper wire must be flexible, the wire is softened or annealed at this point.
LOROM’s modern inductive annealing equipment provides the guarantee for very fine-grained microstructures and high-quality surfaces with the contactless heating of the wire. They were developed specially for non-ferrous metal alloys with low thermal and electrical conductivity.
Annealing is the metallurgical term for heating copper and subsequently cooling it to change its properties (such as its hardness or durability).
Annealing copper makes it softer and less brittle, which allows you to bend it without breaking it. This allows you to use the copper in ways you could not otherwise, such as in our fine wire and cable products.
Annealing is accomplished by passing a large electrical current through the wire for a fraction of a second, raising its temperature briefly to 1000oF/250C The wire, now soft and flexible, solid metallic materials are crystalline in structure. The element atoms bound together to make the bulk material are arranged in a regular, repeating three-dimensional array.
Copper, as are most metals are polycrystalline. They are composed of aggregations of crystals joined at boundaries. Aggregations of unit crystals are termed grains and the boundaries between them are the grain boundaries.
The annealing process controls grain size. The metal is heated to a temperature above its recrystallization temperature. At this temperature the atoms in the cold work distorted crystalline structure use the cold work energy stored in the crystal lattice plus energy absorbed from heating to nucleate into new orderly crystalline patterns.
These new grains are then capable of absorbing new amounts of cold work. The size of the new grain depends on the annealing temperature, the time at temperature, the preceding amount of cold work and the grain size from the preceding anneal.
Grain size measurement is predicated on the assumption that in fully annealed wrought metal the grain morphology is equaled; the apparent size of each grain is essentially the same for any axis of measurement.
In reality, a metal structure is an aggregate of grains varying in size and shape.
The grain size is an estimate of the average size and is reported in millimeters. (ASTM E112.)
Considerations of Grain Size:
Strength
Fine grains produce wire of lower elongation and higher mechanical properties.
Directionality
Grain directionality occurs when metal is cold worked in one direction between anneals. Directionality (Good Way Bends) can be minimized by fine grain size.
Form-ability
Grain boundaries impede plastic flow. The larger the grain size, the fewer the grain boundaries and the greater the potential for deformation.
Surface Appearance
Slip within a grain’s lattice structure resulting from cold work causes surface roughness (orange peel). The finer the grain size, the smoother the cold worked surface.
ALLOY 135 :
Cadmium free /Copper Alloy:
These cadmium free alloys provide similar strength to conductivity and are not containing potentially hazardous substances per OSHA Regulations.
CS 95 Beryllium/Copper Alloy:
Extremely high strength, high cost, marginally conductive wire.
This material is used where flex fatigue is more critical than conductivity. Flex fatigue data suggests over 50 X the flex life for a comparable copper conductor.
Wire Gauge Reference Table
Copper clad steel conductor’s and silver plated copper clad steel
Properties: The main properties of these conductors include: Good corrosion resistance of copper High tensile strength of steel Resistance against material fatigue
Advantages: Since the outer conductor layer is low-impedance copper and the center is higher impedance steel, the skin effect gives copper-clad RF transmission lines impedance at high AC frequencies similar to that of a solid copper conductor.
Tensile strength of copper-clad steel conductors is greater than that of ordinary copper conductors permitting greater span lengths than with copper.
Another advantage is that smaller diameter copper-clad steel conductors may be used in coaxial cables, permitting higher impedance and smaller cable diameter than with copper conductors of similar strength.
Due to the inseparable union of the two metals, it deters theft since copper recovery is impractical and thus has very little scrap value.
Installations with copper-clad steel conductors are generally recognized as fulfilling the required specifications for a good ground. For this reason it is used with preference by utilities and oil companies when cost is a concern.
Magnet Wire
The term “magnet wire” describes solid conductors insulated with a polymer-based film.
The films provide a uniform dielectric coating while taking up little space. Although copper is the primary conductor material due to its superior conductivity & relatively low cost, other metals & alloys may be utilized.
In selecting & specifying a magnet wire, there are several areas of concern.
- Size or Diameter
- Insulation Thermal Class
- Insulation Build or Thickness
- Additional Characteristics such as colour or addition of bondable coating.
Many film insulations are available for magnet wire offering different characteristics. The primary classification factor for magnet wire is “Thermal Class” which dictates its recommended maximum continuous operating temperature for the insulation. Standard thermal classes range from 105 degrees. up to 220°C.
LOROM in-house made and designed drawing dies are typically made of tool steel, tungsten carbide, or diamond, being the most common.
For drawing very fine wire a single crystal diamond die is used. The dies are placed in a steel casing, which backs the die and allow for easy die changes.
Die angles usually range from 6–15°, and each die has at least 2 different angles:
- Entering angle
- Approach angle
Middle Drawing
The coil of copper wire is then transferred by to the middle drawing area of the plant, the first step in this process is to further reduce the size of the copper wire by drawing it through wire draw operating the same way as rod break down.
This process makes use of diamond dies to reduce a 10- or 12-awg wire to one 19-, 22-, 24- or 26-awg wire.
Fine Drawing
After the middle drawing the copper is transferred to the fine wire area of the Hangzhou plant, the process of drawing even finer wire with state of the art low-tension machinery Lorom fine wire capability is only achieved by pinpoint accuracy.
We can draw down to AWG50 .000986″ or 0.02505 mm, the same physical size as a single silk thread produced by silk spiders.
Copper Plating Options
Tin: Good solderability and corrosion protection
Silver: Good solderability and high conductivity
Nickel: Corrosion protection and temperatures up to 250°
Enamel: Protection for ultra fine wire
Twisting & Stranding
Our modern state of the art twisting and bunching machines are with capabilities from large rope constructions to concentric constructions dependent on the end user application especially fine wire twisting is challenging due to control of vital parameters such as elongation and concentricity.
All of our equipment has magnetic clutches as well as refined and sophisticated tension control equipment, most of which is made in house. Lay length has an effect on flex life and shortening the lay length will increase flex life slightly.
Conductor construction (with the same number of strands) e.g. true concentric, unilay etc. will also influence flex life, however the effects of these attributes are less significant than the material’s tensile strength, elongation and strand count.
Bunch: Composed of any number of the same diameter wires twisted together in the same direction without regard to geometric arrangement of individual strands. Common constructions are 7,10,16,26,41,65, and 105 strands. This strand construction offers the lowest cost.
True Concentric: Central wires surrounded by one or more helically laid wires with a reversed direction of lay and increase length of lay for each successive layer. Helically laid cores offer improvements in mechanical strength and crush resistance. True concentric reduces corona hence is used often for high voltage cables.
Unilay: Composed of more than one layer of helically wrapped wires, with same lay direction and length of lay for each successive layer. Unilay offers the smallest diameter and lowest weight of helically laid core constructions.
Rope stranding: The most flexible of stand constructions it is generally used for 8 AWG or larger, however very high strand configurations are available for almost all AWG wires.
