Apparel Online Bangladesh Magazine November Issue 2018 | Page 47

Operator utilisation is 440/480
expressed in percentage, i.e. 91.67%
(how productively the operator’s
time is utilised).
SMV earned by operator is 500
pieces x 0.80 minutes/piece = 400
minutes. So, operator efficiency will
be 400/480 expressed in percentage,
i.e. 83.33% (how efficiently the
operator’s time is used).
Balance inefficiency (used
commonly in Japanese literature)
calculation is similar to efficiency
calculation above, but generally
calculated for a line from a different
perspective.
Basically how much time is
proportionately lost due to
imperfect balance, as the
primary reason behind time loss
is attributed to poor balancing.
Suppose in a sewing line of 20
operators, a style of 20 SMV is
produced in 8-hour shift. If the
average daily production of the
style is 400 pcs/shift, then
Minutes produced = SMV x pcs/
shift = 20 x 400 = 8000
Minutes attended = Number of
operators x Number of minutes
per shift
= 20 x 480 = 9600
Out of 9,600 minutes available, only
8,000 minutes of worth is produced,
rest minutes are lost due to line
imbalance. Thus, balance efficiency
is 8000/9600, i.e. 83.33%.

If 83.33% is balance efficiency,
then balance inefficiency is 100-
83.33 = 16.67%.
Takt Time and Pitch Time are
same
RIGHT
Takt Time comes from a German
word ‘takt’ meaning rhythm or beat.
Takt Time sets the ‘beat’ of the
organisation in sync with customer
demand. Takt Time is a simple
concept, yet counter-intuitive, and
is often confused with Cycle Time
or machine speed. Takt Time is
the pace of production needed
to meet customer demand or
production target. The formula for
Takt Time is:
It is calculated as:
Time available for production (Number
of operators x Time contracted)
Target or Required number of pieces
For example:
Net available time to work =
1 shift x 8 hrs. x 60 min. x 20
operators = 9600 minutes
Customer demand (production
target) = 2400 pieces
Takt Time = (9600 minutes)/2400
= 4 minutes/piece
This means a unit needs to be
completed every 4 minutes.
Therefore, every step or operation in
assembly needs to be done/delivered
every 4 minutes (or multiples of it).
Pitch Time is the theoretical operation
time; each operator should take for a
planned balanced line. It is
calculated as:
(SAM value of a garment)
(No. of operators required to meet
the target)
Suppose the work content (SAM value)
of a garment is 40 minutes and there
are 10 operators available to meet
the target, it means while working
in assembly line each operation
should take 4 minutes to have a
balanced line. Clubbing and Splitting
of operations are done to match each
operation’s timings with Pitch Time.
Lesser the deviation of operation
timings from Pitch Time, better
the balancing efficiency that can
be achieved.
Both Takt Time and Pitch Time can
never be measured using a stop watch,
both are always calculated.
Throughput Time and Flow Time
are different
RIGHT
Throughput Time is the time required
from one cut component fed till the
final garment comes out at the end
of sewing line. It is the total elapsed
time between the point at which cut
component enters the sewing line
to the point at which the complete
garment exits. Throughput Time is the
total work content of the style
(in critical path) plus the total
waiting time.

Although
Time Study is
commonly used
in the industry,
complete
exercise is
‘Motion and
Time Study’,
where Time
Study is to
establish
Target Time
(that is
achievable).
Motion Study
explores
possibility
of improving
it through
methods
improvement.
Throughput Time = (Work content
of the style in critical path) x (1 +
WIP)
In other literature, Throughput
Time is defined as the rate at which
the production happens. While the
elapsed time between the point at
which cut component enters the
sewing line to the point at which the
complete garment exits, is termed as
Material Flow Time or Flow Time. If
Throughput Time is represented by T
and Flow Time by F, then inventory (I)
can be calculated by I = T x F
For example, if the Flow Time (F) for a
garment assembly process is 10 hours
and rate of production (throughput)
is 60 pieces per hour, then inventory
in the line is 600 garment equivalent,
of cut components and partially sewn
components.
Time Study and Capacity Study are
different
RIGHT
Although Time Study is commonly used
in the industry, complete exercise is
‘Motion and Time Study’, where Time
Study is to establish Target Time (that
is achievable). Motion Study explores
possibility of improving it through
methods improvement. In many of the
cases in organisations, Time Study
is conducted but the aim is not to
establish the target but to only assess
the capacity of existing work force.
While Time Study is cumbersome
and time consuming, capacity study
can be done quickly and easily where
element breakdown of operations
are not necessary. Simply Cycle
Time taken for complete sewing
operation (from pick-up to dispose
of) can be calculated to assess how
many pieces can be made by existing
workforce with existing methods and
infrastructure. The time lost and
hidden potential for improvement are
never identified in capacity study.
Cycle Time is more important than
standard time as it gives an accurate
indication of what can be achieved.
For balancing purposes, it is much
better to use achieved cycle times than
standard times.
www.apparelresources.com | November 2018 | Apparel Online Bangladesh
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