Processing of Tungsten Filament in Electric Bulb

Introduction:
Tungsten filament is a crucial component used in electric bulbs due to its high melting point and resistance to high temperatures. The process of producing tungsten filaments involves several steps to ensure the desired properties and performance of the filament.

Extrusion:
Extrusion is the primary method used for processing tungsten filaments in electric bulbs. It involves forcing the tungsten material through a die to create the desired shape and dimensions. The extrusion process begins with tungsten powder mixed with binders to improve its plasticity. This mixture is then fed into an extrusion machine. The machine applies pressure to force the material through the die, resulting in a continuous filament. The extruded filament is then cut to the desired length and undergoes further processing steps.

Wire Drawing:
After extrusion, the tungsten filament is further processed through wire drawing. Wire drawing is a metalworking process that reduces the diameter of the filament while increasing its length. The extruded filament is passed through a series of dies with progressively smaller diameters. As the filament passes through each die, it is pulled by a drawing machine, elongating and reducing its diameter. This process helps refine the filament's dimensions and improve its mechanical properties.

Casting:
Casting is not the preferred method for processing tungsten filaments in electric bulbs. Casting involves melting the tungsten material and pouring it into a mold to create the desired shape. However, tungsten has a significantly high melting point, making it challenging to achieve the required temperature for casting. Additionally, casting may result in uneven distribution of impurities and inconsistencies in the filament's structure, affecting its performance.

Powder Metallurgy:
Powder metallurgy is a manufacturing method that involves the compacting and sintering of metal powders to create solid components. While powder metallurgy can be used to produce tungsten components, it is not commonly employed for processing tungsten filaments in electric bulbs. This method may not provide the desired level of control over the filament's dimensions and properties compared to extrusion and wire drawing.

Conclusion:
In conclusion, the processing of tungsten filament used in electric bulbs primarily involves extrusion and wire drawing. These methods allow for precise control over the filament's dimensions, mechanical properties, and overall performance. Casting and powder metallurgy are less commonly used due to the challenges they pose and the potential limitations in achieving the desired filament characteristics.