Question

The common type of Staple fibre produced during synthetic fibre manufacture is

• A. \(1.2\text{D} \times 38\text{ mm}\)
• B. \(1.5\text{D} \times 38\text{ mm}\)
• C. \(2\text{D} \times 38\text{ mm}\)
• D. \(1.4\text{D} \times 38\text{ mm}\)

Hint:

Remember the standard synthetic staple fibre specification: \[ \boxed{ 1.5\text{D} \times 38\text{ mm} } \] where \[ \begin{aligned} \text{Denier (D)} &\rightarrow \text{Fibre fineness}, \text{38 mm} &\rightarrow \text{Staple fibre length for cotton spinning}. \end{aligned} \] This specification is one of the most frequently asked objective questions in textile engineering examinations.

Answer 1

The Correct Option is B

Concept: Synthetic fibres are generally manufactured as continuous filaments. When these filaments are cut into short lengths suitable for spinning, they are called staple fibres. A staple fibre is characterized by two important parameters:
• Denier (D): It indicates the fineness of the fibre.
• Cut Length (mm): It represents the length of the staple fibre. Denier is defined as \[ \boxed{ \text{Denier}=\frac{\text{Weight (g) of }9000\text{ m of fibre}}{} } \] A lower denier indicates a finer fibre, whereas a higher denier indicates a coarser fibre. For cotton spinning systems, the most commonly manufactured synthetic staple fibre is \[ \boxed{1.5\text{D} \times 38\text{ mm}.} \] This specification provides a good balance between spinnability, strength, and yarn quality.

Step 1: Understand the significance of denier and cut length.
The denier determines the fineness of the fibre. \[ \begin{aligned} 1.2\text{D} &\rightarrow \text{Very fine fibre}, 1.5\text{D} &\rightarrow \text{Standard apparel fibre}, 2.0\text{D} &\rightarrow \text{Coarser fibre.} \end{aligned} \] Similarly, the cut length influences the spinning system. A cut length of \[ 38\text{ mm} \] is widely used for cotton spinning machinery.

Step 2: Recall the standard commercial staple fibre specification.
In textile industries, polyester and viscose staple fibres are commonly produced in the standard specification \[ \boxed{ 1.5\text{D} \times 38\text{ mm}. } \] This size is preferred because it offers
• Good fibre cohesion,
• Smooth drafting,
• Better yarn strength,
• Compatibility with cotton spinning systems. Hence, it is regarded as the most common staple fibre specification.

Step 3: Examine each option.
Option (A): \(1.2\text{D} \times 38\text{ mm}\) This is finer than the standard commercial staple fibre and is used for specialized applications. \[ \boxed{\text{Incorrect}} \] Option (B): \(1.5\text{D} \times 38\text{ mm}\) This is the most commonly manufactured staple fibre specification used in synthetic fibre production. \[ \boxed{\text{Correct}} \] Option (C): \(2\text{D} \times 38\text{ mm}\) This is comparatively coarser and generally used for technical or industrial applications. \[ \boxed{\text{Incorrect}} \] Option (D): \(1.4\text{D} \times 38\text{ mm}\) Although available for certain applications, it is not the standard commercial staple fibre specification. \[ \boxed{\text{Incorrect}} \]

Step 4: Write the final answer.
Therefore, the common type of staple fibre produced during synthetic fibre manufacture is \[ \boxed{ 1.5\text{D} \times 38\text{ mm}. } \] Hence, \[ \boxed{\text{Option (B) is the correct answer.}} \]