Apparel Online Bangladesh Magazine July Issue 2018 | Page 46

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Myth Buster
All you need to know
about computerised
sewing machines
Single needle lockstitch machines with needle positioner and underbed trimmer are commonly known as computerised
sewing machines in the industry. Generally around 15-25% of the sewing machines on the sewing floor are computerised.
These machines surely possess additional features, thus offering additional benefits over ordinary single needle
lockstitch machines. However, there are some common fallacies which need to be demystified.
All sewing machines on my
shopfloor should be computerised
WRONG
The computerised sewing machine
often represents the so-called
‘state-of-the-art’ sewing machine.
During upgradation of facility or
in a race to put up ‘state-of-the-
art’ sewing floor to impress upon
fellow manufacturers or buyers,
manufacturers often buy all
computerised machines on their
shopfloor. A typical computerised
single needle lockstitch machine
can perform needle positioning,
underbed thread trimming, back
tack and step programming. We
need to analyse all the operations
wherein we require these features.
For example, when we stitch small
parts in chain to maintain the
sequence of ticket numbers, we may
not require thread trimming facility.
Similarly, all operations where seam
end goes inside subsequent seams
may not even require back tack and
so on. It is observed that needle
positioning is the most wanted
feature and step programming is
the least used feature. A study by
a leading sewing machine brand
reveals that appropriate selection
of computerised sewing machine
on the shopfloor can lead to
approximately 13% improvement
in productivity.
Against common
belief that
sensors raise
alarm when
bobbin thread
exhausts,
these sensors
actually raise
alarm when a
pre-determined
amount of thread
is left in the
bobbin. This
is to ensure
that existing
cycle of sewing
is complete
and bobbin is
replaced before
the next cycle
starts.
Programming of features in
computerised machine is very
complex, operators can’t do it All computerised sewing
machines can program number of
stitches
WRONG WRONG
The icon-based programming is very
easy and even operators can do it.
Nowadays different settings can be
saved and simply called in during
change of style. Computerised machines may come
with only needle positioner and
underbed trimmer and may not
have step programming facility. It
is the step programming facility
which can count the number of
stitches and which could be pre-
programmed based on total length
of stitch and SPI (Stitches Per Inch)
being set. For example a length of 5
inches seam at 12 SPI theoretically
will have 60 stitches. However,
as fabric is a dimensionally
unstable material, operator has to
actually stitch, count and program
real number of stitches. Earlier
different models were available
with or without step programming
facility; however, nowadays
generally all brands offer
computerised sewing machines
with all features, namely: needle
positioned, underbed trimmer,
back tack and step programming.
Computerised lockstitch machines
can raise alarm before bobbin
thread exhausts
RIGHT
Against common belief that
sensors raise alarm when bobbin
thread exhausts, these sensors
actually raise alarm when a pre-
determined amount of thread is
left in the bobbin. This is to ensure
that existing cycle of sewing is
complete and bobbin is replaced
before the next cycle starts. Some
of the computerised lockstitch
machines are equipped with
proximity sensors, which can be
programmed to sense and raise
alarm based on remaining thread
in bobbin. The amount of remaining
thread can be programmed based
on requirement. An operation like
shirt front placket stitching requires
to be programmed with more
amount of remaining thread, then
an operation like pocket attaching
takes place.
46 Apparel Online Bangladesh | July 2018 | www.apparelresources.com
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