Melt Spinning Process | Advantages and Disadvantages of Melt Spinning

What is Melt Spinning Process?

Melt spinning is one of the most convenient and economic method of manufacturing polymeric/synthetic fibres. In melt spinning polymer (fibre-forming substance) is melted and pumped through a spinneret (die) with numerous holes (one to thousands). The molten fibres are cooled, solidified, and wound on a suitable package. Melt spinning uses the heat to melt the polymer to a viscosity which is suitable for the extrusion through the spinneret. 

Polymer chips are obtained from previously reacted chemical combinations. These polymeric chips are melted and then pumped at specific rate through a spinneret. The extruded filaments are cooled to solidify continuous filaments. Stretching of the fibres in both the molten and solid states can be done to improve orientationof the polymer chains along the fibre axis. This method of spinning is suitable in manufacturing the polyester, nylon 6,6, etc. We can spin the fibres with different cross section using melt spinning technique. Fibres can be extruded from the spinneret having different cross-sectional shapes (round, pentagonal, octagonal, trilobal, etc.). The melt spinning process is as shown in fig.1

Trilobal shape-shaped
More light reflection, Attractive look. 
Offer glitter-free effects.
Hollow fibres
Provide insulation

Requirements for Melt Spinning

The melt spinning process can be applied to the production of filament when the polymer on melting will give a viscous liquid without decomposition. Following are the requirements for melt spinning:

  1. The polymer should not be volatile. 
  2. The fibre forming polymer must have melting point. 
  3. The polymer should not decompose in the molten state. (It should not degrade when heated).

Fig. 1 Melt Spinning
Fig. 1 Melt Spinning

Steps involved in Melt Spinning

  1. Feeding of the polymer to the hopper in the form of chips. The polymer chips are feed to the extruder via hopper. These polymer chips should be free from moisture.
  2. The chips are feed to the extruder & then forced forward through the barrel by the rotating screw. As the polymer moves forward it is softened. When it reaches the end of the screw then the homogenized melt is filtered and guided to spin pack.
  3. Uniform feeding of molten polymer & filtration in spin block.
  4. Extrusion of the molten polymer into filament.
  5. Solidification of extruded molten filament by cooling media, usually air at quench chamber.
  6. Application of spin finish.
  7. Collection of filament is a suitable package.
  8. Post spinning operations for end use properties.

Advantages of Melt Spinning Process

  • Direct and simple process.
  • High production speed (2500-3000) ft/min.
  • Low investment cost.
  • No solvent recovery process is required.
  • The property of the end products can be controlled by suitable manipulation. 
  • Can be used for both staple and continuous filament.
  • No environment pollution.

Disadvantages of Melt Spinning Process

  • It is suitable for only thermoplasticfibre.
  • Due to higher solidification rate, structural development of fibre is poor.
  • Due to inadequate structural development, maximum strength can’t be achieved easily. 
  • Heat of input is high. 
  • Accurate and precise temperature control is necessary.
  • Required more proper maintained of machine.

Fibres Spun by Melt Spinning

Polyester, Nylon, Olefin, Polypropylene, Saran, etc.

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