Nickel 80% Chromium 20% Nicr Alloy Wire For Plastic Bag Sealing Industry
1. Detailed Description
Nichrome is basically a name given to nickel-chromium resistance wires. It is a non-magnetic alloy, which consists of 80 percent nickel and 20 percent chromium by weight, and is widely used in heating elements because of its relatively high resistivity. Out of the constituents of nichrome, nickel is an element with the chemical symbol Ni and atomic number 28, whereas chromium is an element with the symbol Cr and atomic number 24. Nickel is generally a silvery-white lustrous metal, and chromium, a steely-gray and hard metal. Nichrome, the alloy, is silvery-gray in color, resistant towards corrosion, and has a high melting point.
Physical Properties of Nichrome
The ultimate tensile strength of nichrome is 105,000 PSI (Pounds per Square Inch) and yield strength is around 50,000 PSI. Following are some of the other physical properties of nichrome.
· Electrical Resistivity at room temperature: 1.0 x 10-6 to 1.5 x 10-6 ohm m
· Thermal Conductivity: 11.3 W/moC
· Magnetic Attraction: None
· Thermal Expansion Coefficient (20oC to 100oC): 13.4 x 10-6/oC
· Temperature Coefficient of Resistivity (25oC to 100oC): 100 ppm/oC
· Specific Gravity: 8.4
· Density: 8400 kg/m3
· Melting point: 1400oC
· Specific Heat: 450 J/kgoC
· Modulus of elasticity: 2.2 x 1011
2. Sealing Machine
For a vertical form-fill-seal the film approaches the back of a long hollow conical tube, which is called the forming tube. When the center of the plastic is near the tube, the outer edges of the film form flaps that wrap around the conical forming tube. The film is pulled downward around the outside of the tube and a vertical heat-sealing bar clamps onto the edges of the film to create the "fin Seal", bonding the film by melting the seam edges together.
To start the bagging process, a horizontal sealing bar creates the "Bottom Seal" by clamping across the bottom edge of the tube, bonding the film together, and cutting off any film below. This sealing bar can be on a fixed height, which is called an intermittent sealing process. Faster systems include a sealing bar that moves down with the bag while sealing. This is called a continuous process. The product is either pre-measured by a multi-head weighing system or the sealed tube end is then lowered onto a precision weighing table and the product to be bagged is dispensed through the long conical tube in the center of the bag. When the gross weight of the product-filled bag is reached, filling stops, and the horizontal sealing bar seals the top of the bag, simultaneously forming the bottom of the next bag above. This bag is then cut off from the tube and is now a sealed package, ready to advance onward into the product boxing and shipping processes.
Nichrome Wire
Type | Max. Operating
Temperature | Resistivity @ 20°C (68°F)
Ω mm2/m (Ω/cmf) | Applications | Oxidation
Resistance |
| 20 | 1050°C (1920°F) | 0.95 (572) | Terminals attached to nickel-chromium heating elements, element fasteners, refractory anchor bolts | Moderate |
| 30 | 1050°C (1920°F) | 1.03 (620) | Solid hot plates, open coil heaters in HVAC systems, heaters, de-icing elements | High |
| 40 | 1100°C (2010°F) | 1.04 (626) | Heaters, de-icing elements, heating cables and rope heaters, resistors |
| 60 | 1150°C (2100°F) | 1.11 (668) | Household heating elements, moderate heat, high humidity environments |
| 70 | 1250°C (2280°F) | 1.18 (709) | Industrial furnace electrical heating elements |
| 80 | 1180°C (2150°F) | 1.09 (656) | Industrial furnaces, home appliance heating elements |
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Nickel 80% Chromium 20% Nicr Alloy Wire For Plastic Bag Sealing Industry Images
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