Influence of torque value:

Aprons in the drafting system along with other components play a vital role in deciding the overall spinning performance and yarn quality. Increased in output of ring spinning machines over the years is phenomenal. Nearly 40% increase in speeds of spindle had been happened. Still life span of a drafting apron is defined by the frequency of flexing, has remained virtually the same, the improvements in rubber polymer are evident.

General construction of aprons:

In general drafting aprons are made by NBR based synthetic rubber. There are also other materials involved like leather, synthetic leather, poly urethane, PU coated materials in apron manufacturing. Still synthetic rubber is an ideal material for this purpose because of its long life and resistance to fibre finishing additives and abrasion.

A typical rubber compound for the outer or inner layer of an apron contains the base polymer as well as 15 additives, which also affects the various physical and mechanical properties.

Basically, aprons made of synthetic rubber are made in endless tubular form whereas leather aprons are made in open strips and subsequently glued together to form an apron, the advantage of tabular construction is the lack of seam and uniform along its circumference.

Aprons used in ring frames and speed frames are generally made out of three layers:

• Outer layer
• Reinforcing layer
• Inner layer

The outer layer of spinning apron is finish ground to provide it a defined roughness for optimum fibre guidance. The maximum load is placed on traverse zone. Here abrasion and the pressure from the bundle of fibres lead to smoothing and formation of groove. The duration of time for which an apron can create optimum yarn quality mainly depends on the rubber compound. Resistance to abrasion and elasticity determine how long the initial structural geometry of an apron outer layer lasts.