Time
study is a work measurement technique commonly used by apparel engineers to
determine the rate at which a specific operation is performed. The objective of
a time study is to develop and check production standards.
An operation is
studied by time analysts while a style is in production. Time studies are an
appropriate method of work measurement for high-volume operations with a high
degree of repetitiveness. They are frequently used to establish production
standards for operations performed in a progressive bundle system.
1. Time
Study Procedure:
The
procedure for time study can best be described step-wise, which is self-explanatory.
1. Select Garment
At first garment has to be selected
for time study which has not been studied before. A time study is conducted by
analysts while a style is in production.
2. Identify operation
The garment is analyzed to identify the process or operation for study. A time study also requires a method description
for the specific operation to be done. Time study may be conducted on a
specific operation rather than a whole garment, which has not been
previously studied or the method has been changed recently or there are any
complaints regarding time standard.
3. Break the operation down into elements
To prepare a time study, analysts
break the operation down into elements. Each element involves a group of
motions with a definite beginning and end that can be identified and timed.
Elements of the operation are listed in the left column of the time study
sheet. Potential elements for a sewing operation may include
- Picking up and positioning parts
- Matching and aligning parts
- Positioning parts to the needle or presser foot
- Sewing
- Disposing of parts
Machine-controlled elements are
separated from manually controlled elements on cycle machines because they are
always constant.
4. Select operator
A qualified operator must be selected
for study if more than one operator is doing the same task. The selected operator should have the necessary skill, experience, temperament, and knowledge
about the purpose of the study. So selection
of workers for time study is a very important factor in the success of the
study. If there is only one person on the job, there is no choice.
5. Record Cycle time
A time analyst records readings
from a stopwatch or digital time board at the completion of each element. Times
are recorded for each element for 10-20 cycles. A minimum of 10 cycles should be timed to
provide a fair representation of the operation. The amount of lapsed time is
averaged for each element. This is called observed time, which is the
average amount of time that the analyst determined was used to complete each
element.
6. Adjust Rating Factor
To level the observed time to what a
normal operator could do, the operator’s performance is rated by the analyst.
The speed at which the observed operator worked may be above or below the rate
that a normal operator can perform. A rating below 100% reduces the time and
above 100% increases the time allowed for an element to be completed. So it is
necessary to adjust a rating factor with the observed time
Basic time is always constant as an observed rating is increased observed time decreases. The standard rating is 100, the observed
rating may be below or above of standard rating. There are different systems used
but they must be consistent; thus, analysts must be well-trained if time studies
are to be fair and reliable. The performance rating which depends on the
judgment of the analyst is the most difficult and controversial part of a time
study.
7. Determine allowances
To get the standard time, a proper allowance must be added to include the nonproductive time that occurs as part of the production process. An allowance
factor is a percentage of time added to the normal time including
- Machine allowances
- Relaxation allowance
- Interference allowance
- Process allowance
- Contingency allowance
- Special allowance
8. Determine production standard
Production standard is a rate stated in standard allowed
minutes (SAM) or standard minute value (SMV) that reflects the time required
for a normal operator to complete one operation using a specific method. The
production standard is also an indicator of how many times the operation can be
completed in a given time. A total of the production standards of each style
indicates the minimum throughput time to produce a specific style.
SAM or SMV= Basic Time + Allowance
2. Objectives of production
standard
Production standards are
used in production planning to accomplish the following objectives
- Production calculation
- Efficiency calculation
- Performance calculation
- Line balancing
- Load and capacity calculation
- Adjustment of factory capacity
- CM calculation
3. Time Study Equipment
The following equipment
is needed for time study.
1. Timing Device
1. Timing Device
The
stopwatch is the most widely used timing device used for time study, although an electronic timer is also sometimes used. The two perform the same function with
the difference that an electronic timer can measure time to the second or third
decimal of a second and can keep a large volume of time data in memory.
2. Time Study Observation
Sheet
It is a printed form with spaces provided for
noting down the necessary information about the operation being studied, like
name of operation, drawing number, name of the worker, name of time study
person, and the date and place of study. Spaces are provided in the form for
writing detailed descriptions of the process (element-wise), recorded time or
stop-watch readings for each element of the process, performance rating(s) of an operator, and computation. A typical time study observation sheet is as
below.
Operator | Code | |||||||||||||||
Operation | Code | |||||||||||||||
Code | Elements | Cycle | Avg. | Rat. | B/Time | |||||||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | Total | ||||||
1 | ||||||||||||||||
2
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3
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4
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5
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6
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7
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8
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9
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10
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11
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12
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13
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14
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15
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Size
|
Workplace Layout
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Sketch of Parts
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Total Std. Min
| |||||||||||||
Style
|
Allowances
| |||||||||||||||
Fabric
|
SAM/ Pc.
| |||||||||||||||
Machine
|
SAM/ Dzn.
| |||||||||||||||
RPM
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Dzn/ Day
| |||||||||||||||
SPI
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Piece Rate
| |||||||||||||||
Analyst
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Plant
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It is a lightweight board used for holding the
observation sheet and stopwatch in position. It is of a size slightly larger than
that of the observation sheet used. Generally, the watch is mounted at the center
of the top edge or near the upper right-hand corner of the board. The
board has a clamp to hold the observation sheet. During the time study, the
board is held against the body and the upper left arm by the time study person
in such a way that the watch could be operated by the thumb/index finger of the
left hand. Watch readings are recorded on the observation sheet by the right
hand.
4. Other Equipment
This includes a pencil, eraser, device like a tachometer for checking the speed, etc.
4. Advantages and disadvantages of Time
study
Advantage
An advantage of time
study compared to other work measurement techniques is the breakdown and
analysis of the method before time measurement. Time studies measure actual
performance; thus, they provide realistic data on the materials, equipment, and
method being performed.
Disadvantages
Disadvantages are
the time and training required for an analyst to become skilled in conducting
time studies and the fact that operators have to be experienced in the
operation before time studies can be done. Another disadvantage is the
subjectivity of performance rating that must be done by the time analyst.