alloy wire international

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1 alloy wire international resistance wire that s what we do

2 RESISTANCE WIRE This catalogue has been produced to illustrate our range of products and provide valuable technical support. If you need more information please contact us. our aims are simple: Provide a quality product fit for purpose. Provide our customers with the quantity they require - no matter how small. Offer from stock or manufacture to order. Provide a professional, friendly and personal service. 1

3 CONTENTS APPLICATIONS PACKAGING TOLERANCES CHOICE OF MATERIAL HEATING ELEMENT DESIGN SURFACE AREA LOADING DESIGNING A WIRE ELEMENT COILED SPIRAL ELEMENTS DESIGNING A RIBBON ELEMENT USEFUL INFORMATION RESISTANCE WIRE TABLES RESISTANCE RIBBON TABLES size range & available forms: WIRE max: 5.5mm (0.217 ) min: 0.02mm ( ) RIBBON max width: 8mm (0.315 ) min thickness: 0.035mm ( ) max ratio width/thickness: 30:1 STRIP max width: 100mm (3.94 ) SQUARE max: 8mm (0.315 ) min: 0.5mm (0.020 ) OVAL max: 8mm (0.315 ) min: 0.8mm (0.031 ) T max: 4mm (0.157 ) min: 0.8mm (0.031 ) CHAMFER max width: 5mm (0.197 ) ARC max width: 6mm (0.236 ) other shapes available on request 2

4 APPLICATIONS Element wires for:- L Sealers Impulse heat sealers Vacuum sealing T profile wire sealing Electric heating elements Hot wire cutting foam & polystyrene (EPS) Bright or Oxidised wire for electrical resistors. Order quantities from as low as a few feet or metres. high strength hot cutting wire bag sealers heating elements band & cartridge heaters 3

5 PACKAGING Alloy Wire offer varied packaging in the form of coils, spools and cut-lengths, details of which are shown below. Special packaging to individual requirements can also be provided on request. PACKAGING WIRE DIAMETER RANGE (mm) WIRE DIAMETER RANGE (inch) APPROX. NET WEIGHT WIRE (Kg) RIBBON (Kg) WIRE (lbs) RIBBON (lbs) Coil /4 Cat up to 0.25 up to DIN 80 Spool up to 0.25 up to DIN 100 Spool DIN 125 Spool DIN 160 Spool DIN 200 Spool DIN 250 Spool TOLERANCES The tolerance on wire diameter or its resistance shall not vary by more than the following:- DIAMETER TOLERANCE ON DIAMETER mm (.001 ) to < 0.051mm (.002 ) +/ mm (.0001 ) 0.050mm (.002 ) to < 0.375mm (.0148 ) +/ mm (.0002 ) 0.375mm (.0148 ) to < 0.800mm (.032 ) +/ mm (.0004 ) 0.801mm (.032 ) to < 1.25mm (.048 ) +/ mm (.0005 ) 1.25mm (.048 ) to < 2.00mm (.080 ) +/ mm (.0006 ) 2.00mm (.080 ) to < 3.25mm (.128 ) +/ mm (.0008 ) 3.25mm (.128 ) to < 4.75mm (.1875 ) +/ mm (.001 ) 4.75mm (.1875 ) to < 5.50mm (.212 ) +/ mm (.0015 ) DIAMETER TOLERANCE ON RESISTANCE PER UNIT LENGTH mm (.001 ) to < 0.051mm (.002 ) +/- 12% 0.051mm (.002 ) to < 0.076mm (.003 ) +/- 10% 0.076mm (.003 ) to < 0.15mm (.006 ) +/- 7% > 0.15mm (.006 ) +/- 5% The tolerance on resistance for ribbon shall not vary by more than +/-5% 4

6 CHOICE OF MATERIALS RESISTANCE / HEATING WIRES GRADE RW 80 APPROXIMATE CHARACTERISTICS AND SPECIFICATION ELECTRICAL DENSITY MAXIMUM MELTING COEFFICIENT ELECTRICAL CHEMICAL TYPICAL APPLICATIONS REFERENCE RESISTIVITY (g/cm 3 ) OPERATING POINT OF EXPANSION RESISTIVITY COMPOSITION NUMBERS AT 20 O C TEMPERATURE ( µm/m. O C) AT AT 20 O C (Ohm. (Microhms.cm) O C Circ. Mil/ft) NICKEL 80% This alloy is for use at operating W.Nr O C 1400 O C CHROME 20% temperatures up to 1200 O C. Applications include heating elements UNS 2200 O F 2550 O F in both domestic and industrial NO6003 appliances and in control resistors. RW 45 NICKEL 45% A copper-nickel alloy used mainly for W.Nr O C 1270 O C COPPER 55% its medium range electrical resisitivity and very low O F 2320 O F temperature-coefficient of resistance. RW 135 IRON BAL This iron-chrome-aluminium alloy W.Nr O C 1500 O C CHROME 20% performs well at high temperatures ALUMINIUM 5% although cold working is inferior to 2280 O F 2730 O F nickel-chrome alloys. It also has high resistivity. HOT CUTTING WIRES NAME CHARACTERISTICS AND ELECTRICAL DENSITY MAXIMUM MELTING COEFFICIENT TYPICAL APPLICATIONS RESISTIVITY (g/cm 3 ) OPERATING POINT OF EXPANSION AT 20 O C TEMPERATURE ( µm/m. O C) AT (Microhms.cm) O C RW 70 RW 118 RW 122 These hot cutting wires have high strength at elevated temperatures and are used for cutting foam, polystyrene (EPS) and or heat sealing woven polypropylene bags. RW 118 has the best performance on many different machine models. Some machines and operations prefer RW 122 or RW O C 1375 O C O F 2500 O F O C 1370 O C O F 2500 O F O C 1430 O C O F 2600 O F RW 41 This wire has exceptional strength at elevated temperatures and is the ultimate highest performing hot cutting wire. It is used on production lines cutting foam, polystyrene (EPS), thermal laminate materials etc. It has an excellent track record for working on machines running 24 hour shifts and on oscillating cutting frames O C 1345 O C O F 2450 O F 5 To achieve the best cut, adjust the temperature and cutting speed. The material type and it's density will influence the cutting speed.

7 HEATING ELEMENT DESIGN & CALCULATION RESISTANCE / HEATING RIBBON AND WIRE To perform as a heating element the ribbon or wire must resist the flow of electricity. This resistance converts the electrical energy into heat which is related to the electrical resistivity of the metal, and is defined as the resistance of a unit length of unit cross-sectional-area. Thus, the linear resistance of a length of ribbon or wire may be calculated from its electrical resistivity. As a heating element, ribbon offers a large surface area and therefore, a greater effective heat radiation in a preferred direction, making it ideal for many domestic appliances like toasters and convector heaters, and industrial applications such as injection moulding band heaters. An important characteristic of these electrical resistance alloys is their resistance to heat and corrosion, which is due to their formation of oxide surface layers that retard further reaction with the oxygen in air. When selecting the alloy the operating temperature, the material and atmosphere with which it comes into contact must be considered. As there are so many types of applications, variables in element design and different operating conditions, the following equations for element design are given as a guide only. ELECTRICAL RESISTANCE AT OPERATING TEMPERATURE Where: p = Electrical Resistivity (microhm.cm) R = Element Resistance at 20 O C (ohms) d = Wire diameter (mm) t = Ribbon thickness (mm) b = Ribbon width (mm) I = Ribbon or Wire Length (m) a = Ribbon or Wire cross sectional area (mm 2 ) Wire: Ribbon: a = π x d 2 4 a = t x (b - t) + (0.786 x t 2 ) R = p x I x 0.01 (ohms) a With very few exceptions the resistance of a metal will change with temperature, which must be allowed for when designing an element. As the resistance of an element is calculated at operating temperature, the resistance of the element at room temperature must be found. To obtain the element s resistance at room temperature, divide the resistance at operating temperature by the temperature-resistance factor shown below. Where: F = Temperature-Resistance Factor R t = Element Resistance at Operating Temperature (ohms) R = Element Resistance at 20 O C (ohms) R = R t (ohms) F Alloy Temperature-Resistance Factor (F) at: 20 O C 100 O C 200 O C 300 O C 400 O C 500 O C 600 O C 700 O C 800 O C 900 O C 1000 O C1100 O C1200 O C RW RW /55 changes little in resistance as temperature rises, having a temperature-resistance factor of / O C in the O C range. 6

8 SURFACE AREA LOADING It is possible to design an element in a variety of sizes all of which would in theory give the desired wattage load or power density dissipated per unit area. However, it is essential that the load on the surface of the element is not too high as the transfer of heat by conduction, convection or radiation from the element may not be rapid enough to prevent it over-heating and failing prematurely. The suggested surface loading range for the type of appliance and element are shown opposite but this may need to be lower for an element working with more frequent operating cycles, or at nearly its maximum operating temperature, or in harsh atmospheres. Appliance Element Type Suggested Surface Loading Range Area Loading (W/cm 2 ) Fire Spiral Element Fire Pencil Bar Iron Mica-Wound Element Toaster Mica-Wound Element Convector Spiral Element Storage Heater Spiral Element Fan Heater Spiral Element Oven Element Sheathed Element Grill Element Sheathed Element Hotplate Sheathed Element Water Immersion Heater Sheathed Element Kettle Element Sheathed Element DESIGNING A WIRE ELEMENT Where: V = Voltage (volts) W = Wattage (watts) S = Surface Area Loading (W/cm2) R t = Element resistance at operating temperature (ohms) R = Element Resistance at 20 O C (ohms) F = Temperature-resistance factor I = Wire length (m) 1 Example: To calculate the wire diameter and length required for a 750w/240v pencil bar fire element, operating at a maximum temperature of 1100 O C, the total resistance of the element at operating temperature (R t ) will be: R t = V 2 = = 76.8 ohms W Using RW80 wire, the temperature-resistance factor (F) is (see page 6). Thus, the total resistance of the element at 20 O C (R) will be: Knowing the dimensions of the pencil bar, the length of wire that may be wound round it may be estimated. Thus, the resistance required per metre of wire will be: Assuming a length of wire of 9 metres R = R t = 76.8 = ohms F Ohms/m = R = = 7.97 ohms/m l From the table on Page 12, an RW80 wire diameter of 0.417mm has a resistance per metre of 7.91 ohms/m which is closest to 7.97 ohms/m. To verify the actual wire length (l): A change in wire length may mean adding or subtracting turns, or altering the pitch angle of the wire, to achieve the total resistance value. To verify the surface area loading (S): I = R = = m ohms/m 7.91 S = W = 750 I x d x x x = 6.31 W/cm 2 7 This surface area loading should fall within the range shown above for a pencil bar fire element noting that a higher value gives a hotter element. The surface area loading can be higher or lower if it is considered the heat transfer will be better or worse, depending upon the importance of the element s life. If your calculated surface area loading is too high or too low you should re-calculate changing one or more of the following: - The wire length and diameter - The grade of alloy

9 COILED SPIRAL ELEMENTS Wire elements formed into a coil allow a suitable length of wire to be accommodated in a relatively short space, and also absorb the effects of thermal expansion. When forming the coil care must be taken not to damage the wire by nicking or abrasion. Cleanliness of the element is also important. The maximum and minimum recommended ratios of inside-coil diameter to wire diameter are 6:1 and 3:1. The length of the close wound coil may be found using the Table or equation below. x Where: d = Wire diameter (mm) D = Inside-Coil diameter (mm) L = Length of Wire (m) x = Length of close wound coil (mm) x = L x d x 1000 (mm) π x (D + d) d D Wire diameter Length of Close Wound Coil (mm) per 1 meter length of wire Inside Coil Diameter Swg in mm 3mm 4mm 5mm 6mm 7mm 8mm 9mm 10mm When this close wound coil is stretched, the stretch should be about 3:1 as closer windings will result in hotter coils. Apart from accidental damage the service life of a heating element may be shortened by localised burn-outs (hot spots). This may be caused by change to the wire s cross section (e.g. nicks, stretching, kinks), or by shielding an area where the element cannot dissipate its heat freely, or by poor supporting points or terminations. d x x 3 D 8

10 DESIGNING A RIBBON ELEMENT Where: b =Ribbon width (mm) t = Ribbon thickness (mm) 1 Example: To calculate the ribbon size and length required for a 600w/220v mica-wound element in an iron, operating at a maximum temperature of 800 O C, the total resistance of the element at operating temperature (R t ) will be: R t = V 2 = = ohms W Using RW80 ribbon, the temperature-resistance factor (F) is (see page 6). Thus the total resistance of the element at 20 O C (R) will be: R = R t = = ohms F Knowing the dimensions of the mica-board, the length of the ribbon that may be wound round it may be estimated. Thus, the resistance required per metre of ribbon will be: Assuming a length of tape of 7 metres Ohms/m = R = = ohms/m l 7 4 From the table on page 13, a RW80 ribbon size of 1mm x 0.1mm has a resistance per metre of ohms/m which is near to ohms/m 5 To verify the actual ribbon length (l): A change in ribbon length may mean adding or subtracting turns, or altering the pitch angle of the ribbon, to achieve the total resistance value. I = R = = m ohms/m To verify the surface load (S): S = W = x (b + t) x l 20 x ( ) x = 3.92 W/cm 2 As explained for wire elements, if your surface loading is too high or low you should re-calculate changing one or more of the following: - The ribbon length and size DISCLAIMER: Every care has been taken to provide accurate information in this document at time of going to press. Alloy Wire International Limited cannot make guarantees with respect to subject matter or accuracy of this information. Alloy Wire International Limited specifically disclaims all guarantees, expressed, implied or otherwise, including without limitation, all warranties of merchantability and fitness for a particular purpose. We reserve the right to amend or discontinue products and information without notice. 9

11 USEFUL INFORMATION To convert Multiply by To convert Multiply by To convert Multiply by LENGTH Inches to Centimetres Centimetres to Inches Feet to Metres Metres to Feet Yards to Metres Metres to Yards Miles to Kilometres Kilometres to Miles AREA Sq. Inches to Sq. Centimetres Sq. Centimetres to Sq. Inches Sq. Metres to Sq. Feet Sq. Feet to Sq. Metres Sq. Yards to Sq. Metres Sq. Metres to Sq. Yards Sq. Miles to Sq. Kilometres Sq. Kilometeres to Sq. Miles MASS Ounces to Grams Grams to Ounces Pounds to Grams Grams to Pounds Pounds to Kilograms Kilograms to Pounds Tons to Kilograms Kilograms to Tons VOLUME Cu. Inches to Cu. Centimetres Cu. Centimetres to Cu. Inches Cu. Feet to Cu. Metres Cu. Metres to Cu. Feet Cu. Yards to Cu. Metres Cu. Metres to Cu. Yards Cu. Inches to Litres Litres to Cu. Inches Gallons to Litres Litres to Gallons U.S. Pint to U.K. Pint U.S. Gallon to U.K. Pint STRESS lbf/in 2 to kgf/mm kgf/mm 2 to lbf/in tonf/in 2 to N/mm N/mm 2 to tonf/in kgf/mm 2 to N/mm N/mm 2 to kgf/mm lbf/in 2 to N/mm N/mm 2 to lbf/in FORCE lbf to N N to lbf tonf to kn kn to tonf kgf to N N to kgf MISCELLANEOUS lb/ft to kg/m kg/m to lb/ft ft/lb to m/kg m/kg to ft/lb ELECTRICAL ohms/yd to ohms/m ohms/m to ohms/yd ohms/ft to ohms/m ohms/m to ohms/ft microhms/in 3 to microhms/cm microhms/cm 3 to microhms/in microhms to ohms ohms to microhms ohms/g to ohms/lb ohms/lb to ohms/g OHMS LAW TEMPERATURE O C = 5/9 x ( O F 32) O F = (9/5 x O C) ºC ºF ºC ºF

12 RESISTANCES & WEIGHTS OF STANDARD SIZE Diameter SWG AWG mm inch Linear Electrical Resistance (Ohms/m) ALLOY RW80 RW45 RW135 Weight (m/kg) ALLOY RW80 RW45 RW135 wire these values are for bright annealed wires measured at room temperature. 11

13 ELECTRICAL RESISTANCE WIRE Diameter SWG AWG mm inch Linear Electrical Resistance (Ohms/m) ALLOY RW80 RW45 RW135 Weight (m/kg) ALLOY RW80 RW45 RW wire 12

14 RESISTANCES & WEIGHTS OF STANDARD SIZE Width x thickness millimetre (mm) Linear Electrical Resistance (Ohms/m) ALLOY RW80 RW45 RW135 Weight (m/kg) ALLOY RW80 RW45 RW135 5 x x ribbon 3 x 2.5 x x x x x x these values are for bright annealed ribbon measured at room temperature. If required size is not shown, please enquire.

15 ELECTRICAL RESISTANCE RIBBON Width x thickness inch Linear Electrical Resistance (Ohms/m) ALLOY RW80 RW45 RW135 Weight (m/kg) ALLOY RW80 RW45 RW x.156 x.125 x x.0625 x x x ribbon.025 x.0156 x x If required size is not shown, please enquire. 14

16 resistance wire Alloy Wire International Narrowboat Way, Hurst Business Park, Brierley Hill, West Midlands DY5 1UF United Kingdom e: t: +44 (0) f: +44 (0) USA Toll Free t: f: alloywire.com ISO 9001 created for Alloy Wire Int. by Charles Design NJD5266