Page 269 - DMGT206_PRODUCTION_AND_OPERATIONS_MANAGEMENT

Production and Operations Management

Notes
Table 13.1: Assembly Line for Contact Breaker

Preceding Task Operators
Work Predecessor
Work Task Assigned Time/Unit per
Station Station Task (Hours) station

A: Contact Breaker Assembly;
1 - Take Molding Half and clean None 0.010 1
burrs etc.

B: Install contacts A 0.020
C: Install Springs
2 1 B 0.020 2
D: Install plastic levers etc. on
A,C 0.040
Molding Half.
E: Install contacts
A 0.020
F: Install Springs
3 1 B 0.020 2
G: Install plastic levers etc., on
Molding Half. A,C 0.040

H: Close with other Molding G
4 2,3 0.050 2
Half
I: Assemble 4 of the above H 0.008
5 4 1
units
6 5 J: Insert Rivets I 0.040 1
7 6 K: Rivet the sandwich units J 0.098 1
8 7 L: Switching Test under load E 0.050 1
9 8 M: Pack Contact Breaker unit F 0.020 1
Total 0. 354

With a cycle time of 0.098 hours, how many contact breakers are produced daily? If the operation
runs for one 8-hour shift each day, the available productive time each day is 8 hours. Therefore,
maximum daily output can be as follows:
Maximum daily output = available time/(Cycle time/unit)
= 8.0/0.098 = 81.63 units

Since this assembly line can generate 81 units daily, and the requirement is 3000 units per
month, capacity is inadequate.

An alternative method for determining whether capacity is adequate is to calculate the maximum
allowable cycle time give a desired capacity 3000 units/month.

Maximum allowable cycle time = time available/desired number of units
= (8 × 24)/3000 = 0.064 hours/unit
This calculation shows that a layout whose cycle time is 0.064 hours or less will yield the desired
capacity.
Is the sequence of tasks feasible? For now, we will assume that the proposed sequence of tasks
is feasible. By examining the product, we can see the sequence restrictions that must be observed
in its assembly.

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