This document discusses various components used in yarn manufacturing, including aprons, condensers, spacers, and top rollers. It provides details on the materials and construction of aprons, the purpose and placement of different condensers, how spacer size is determined by roving hank, and the properties and functions of top rollers in controlling drafting.

2. Submitted to:
Lecturer
Daffodil International University
Submitted by: Asif Ahmed Tonmoy & Uttom Sen
ID: & ; Sec: B
Course name: Yarn Manufacturing - II
Assignment topic:
Date of Submission: 29.03.2016.
Engr. Md. Mashud Raihan
Details study on apron, condenser,
spacer and top roller.
131-23-3505 131-23-3331

3.  A typical rubber compound for the
outer or inner layer of an apron
contains the base polymer as well as
between 10 and 15 different
additives, which also affect the
various physical and mechanical
properties of the various aprons.
APRON

4.  Basically, aprons made of synthetic
rubber are made in endless tubular
form whereas leather or synthetic
leather aprons are made open in
strips and subsequently glued
together to form an apron. The
advantage of the tubular
construction is the lack of a seam.
The apron is uniform along its entire
circumference.
Aprons for use on ring spinning
machines and roving frames are
made of three layers; in some
special applications used in the long
staple spinning they only have two
layers. It has a thickness of about
1mm and held taut by tensioning
device

5.  The length of the aprons also called as the cradle length is kept
approximately equal to the staple length of the fibers. The cradles for
different staple length are shown in Figure.
Cradle lengths according to the fiber length

6. Feature:
• Condensers are mounted on a reciprocating
bar behind the drafting arrangement.
• The second condenser is provided in break
draft field.
• And the 3rd one is located in main draft field.
Function:
• Spreading sliver masses are condensed to
improve evenness and lead to drafting zone.
Advantage:
• Reduce the high fly level and hairiness of
roving.

7.  Condensers placed in the drafting zone help to prevent the fiber
strand from spreading apart during drafting.
 Condensers can be classified as feed (or inlet) condenser, middle
condenser, and delivery (or floating) condenser (Figure).
 Feed condenser is used just before the back pair of drafting rollers.
The middle condenser is used near the nip of the middle pair of
rollers and the third one is used just before the front pair of rollers.

8. The distance between top and
bottom aprons is maintained by
a small component called "cradle
spacer" or "spacer," which is
inserted between the nose bar
of the bottom apron and the
cradle edge of top apron. The
selection of spacer for a process
depends on the hank of the
sliver, break draft, and roving
hank. Spacer size is 4 to 7 mm in
accordance with roving hank.

9. Spacer size of different roving hanks
Roving Hank Spacer Size X(mm)
Up to 1.0 7-8
1.1-1.8 6-7
1.8-2.5 4-6
2.5 & above 3-4
Advantages and disadvantages of reducing the spacer size

10.  Top rollers are held strictly parallel to and in perfect alignment with bottom rollers.
 Top rollers covered with rubber cots play a significant role in the control of drafting
irregularities.
 The hardness of top rollers
is between 80° and 85°
Shore, but the rollers over
which the apron runs often
have a hardness only slightly
above 60° Shore. This
permits better enclosure
and guidance of the fiber
strand during drafting.

11.  The top rollers must be pressed
with relatively high force against
the lower rollers to ensure
guidance of the fibers. 100- 300
N per roller is normally applied
depending on raw material and
volume of fibers.
 The fiber or dust accumulation
in the top roller neck should be
cleaned frequently using picker
gun.

12.  The top roller must be
pressed with relatively high
force against the lower rollers
to ensure the guidance of
fiber.
 Pressure are in the range of
100 to 250 N per roller which
may vary as per raw material
and its volume.
 Pressure is applied by spring
pressure, pneumatic
weighting, magnetic
weighting.