Taif University College of Engineering
WORK STUDY
8053203-3
Lecture Notes
Draft
Industrial Engineering Program
1-1
WORK STUDY Course ID 8053203-3
Lecture [9 ]
Work Measurement
(Time study).
(How much time a job should take for completion).
work measurements Techniques
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Components of work measurements
Basic time
the time taken by a worker with standard performance.
Basic time is calculated from the observed time by applying the rating factor
Observed Rating
Normal (or) Basic time = Observed time x
Standard Rating
Example (2)
For the case observed time 0.25 and rating 80% 1-3
Example
stopwatch readings are cumulative readings
• Individual timings for each element is calculated by subtracting
proceeding readings from successive
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Example
Solution
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https://www.youtube.com/watch?v=EboPwW8TXtQ
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Example
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The table shows Calculating the basic time in the last column by formula
Note and say
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Example
The standard time is to be established for a manual work cycle by
direct time study. The observed time for the cycle averaged 4.80
min. The worker’s performance was rated at 90% on all cycles
observed. After eight cycles, the worker must exchange parts
containers, which took 1.60 min, rated at 120%. The PFD
allowance for this class of work is 15%.
Determine
(a) the normal time and
(b) the standard time for the cycle.
Solution:
(a) Normal time = 4.80(0.90) + 1.60(1.20)/8
= 4.32 + 0.24 = 4.56 min
(b) Standard time Tstd = 4.56(1 + 0.15) = 5.244 min
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Example
• Given: A direct time study was taken on a manual work element using the
snapback method. The regular cycle consisted of three elements, a, b, and c.
Element d is an irregular element performed every five cycles.
Work element a b c d
Observed time (min) 0.56 0.25 0.50 1.10
Performance rating 100% 80% 110% 100%
• Determine
(a) normal time
(b) standard time for the cycle using Apfd=0.15
Solution:
(a) Normal time:
Tn = 0.56(1.00) + 0.25(0.80) + 0.50(1.10)
+ 1.10(1.0)/5 = 1.53 min
(b) Standard time:
Tstd = 1.53(1 + 0.15) = 1.76 min
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Example-stopwatch time study: ”
• The ACE HEXNUT Company sells hex nut and bolt assemblies.
Their rather primitive assembly method is (a) to have the operator
place the bolt, head down, into the holding fixture. (b) The operator
then places the hex nut on the threaded end and manually tightens
the nut. (c) The completed assembly is then removed from the
fixture and placed in the shipping barrel.
• Each operator is provided with two fixtures, two stockpiles of raw
material, and two shipping barrels. These permit the operator to
simultaneously assemble two products at one time. The following
elements have been developed for performing a time study:
• 1- Reach for and grasp bolt.
• 2- Place bolt in fixture.
• 3- Release bolt; reach for and grasp hex nut.
• 4- Place hex nut on end of bolt.
• 5- Fasten nut to bolt. See next page
• 6- Place bolt in shipping barrel 1-11
Example-stopwatch time study: ”
• Continuous Stop Watch Time
Study was used. Five cycles
were timed and each element
was rated. These results
appear in the table below.
• Unfortunately, stopwatch was
not reset at the beginning and
it was read before start as 3.15
minutes
Use 3% as personal allowances and of 4% as delay allowances
(a) calculate the standard time to complete one assembly.
(b) How many assemblies should the worker be able to
complete in one hour?
Prepared by: Assoc. Prof. Dr. Adham MACKIEH 1-12
Example-stopwatch time study: ”
Solution
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Problem No.1
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Problem No.2
Performance
Observation rating
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Problem No.3
• A direct time study was taken on a manual work element using
the snapback method. The regular cycle consisted of three
elements, a, b, and c. Element d is an irregular element
performed every five cycles.
Work element a b c d
Observed time (min) 0.56 0.25 0.50 1.10
Performance rating 100% 80% 110% 100%
• Determine ; (a) basic (b) normal time and (c) standard time for
the cycle, using allowance factor of 15%.
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Problem No.4
The machining operation of a “Gear- Case Casting”
• In a workshop, a repetitive stopwatch time study was conducted
on the machining operation of a “Gear- Case Casting” shown in
the below drawing
• This operation was divided into 7 elements (A, B, C, D, E, F,
G).
• Only G element is not occurring regularly in every cycle, since
it is to clear the table of the machine from metal ships. Therefore,
element G is occurring every 2 cycles.
• The stopwatch readings(in seconds) are shown in the next table
• The manager of this workshop agrees to use 5% as Personal and
fatigue allowances and 2% as Delay allowances.
• Find the standard time to produce one Gear- Case?
Prepared by: Assoc. Prof. Dr. Adham MACKIEH 1-17
stopwatch time study: the machining operation
of a “Gear- Case Casting”
Note that machine element (E) is not rated and only
delay allowances (2%) were considered
Note that element (G) is not occurring
regularly and only delay fatigue allowances
(5%) were considered
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Problem No.5
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Problem No.6
• How many working minutes do you expect would take a
worker to produce a part for which :
• the time standard is 10 minutes,
• if the allowance for this work is 25% of the normal time
• the worker is rated at 80%?
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Problem No.7
Order taking tine
• calculate the standard time
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Problem No.8
Problem No.9
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TMU stands for Time Measuring
Unit.
• How many TMU is equal to one seconds and one
minute?
• Conversion of TMU to hours, minute and second
1 TMU = 0.000010 hr = 0.00060 minute = 0.036 second
Or conversely
1 second = 27.78 TMU
1 minute = 1667 TMU
1 hour = 100,000 TMU
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THANK YOU
ANY
QUESTIONS?
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Recommended sources
• https://www.youtube.com/watch?v=1607AMNKcTM
• Anupam Kumar Reader SMS Varanasi. Email:
anupamkr@gmail.com
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