In a batch machining operation setup time is 15 hours and ba

In a batch machining operation, setup time is 1.5 hours and batch size is 80 units. The cycle time consists of part handling time of 30 sec and processing time of 1.37 min. One part is produced each cycle. Tool changes must be performed every 10 parts and this takes 2.0 min. Determine (a) average cycle time, (b) time to complete the batch, and (c) average production rate.

Solution

Problem 3.2

Answer :

Given information :

Set up time = 1.5 hours , batch size = 80 units ,

Cycel time = 30 sec

=30 sec * 80 jobs

= 2400 sec

Prcoess time = 1.37 min

= 83 sec * 80 jobs

= 6640 sec

Tool change = = 2 min for 10 parts = 16 min for 80 parts = 960 sec

a ) Avg.cycle time =

Set up time + cycle time +process time + Tool changing time

= 5400 + 2400 + 6640 +960

= 15400 sec

a ) Avg.cycle time = 15400 /80

  = 192.5 sec

b ) Time to complete batch =

Total time for 80 parts

= 5400 + 2400 + 6640 +960

= 15400 sec

Total time for 80 parts = 15400 sec

Avg time = 192.5 sec

c) Avg.production rate = 3600 sec in 1 hr / 192.5 sec time per job

   =18.70

Avg.production rate = 19 no of jobs per hour

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Problem 3.3

Answer :

Set up time = 3 hours

Processing time = 1.60 min per cycle = 96 sec = 115200 sec for 1200 job

2 parts in 1 cycle

Tool handling = 0 sec

Part handling time = 45 sec = 54000 sec for 1200 job

Time for new tray = 3 min

One tray is consisted of 24 jobs .

Batch size = 2400 / 24 = 100 tray

100 tray= 3 min /tray = 300 min

Time required =

Set up time = 3 hours = 10800 sec

Processing time = 1.60 min per cycle = 96 sec (2 parts in 1 cycle)

Tool handling = 0 sec

Part handling time = 45 sec

Time for all tray = 300 min= 18000 sec

Total time =10800+ 115200+54000+18000

= 187200 sec

a ) Avg cycle time = 187200 / 2400

=78 sec

b) Time to complete batch = 187200 sec

C) Avg production run = 3600 sec per hour / 78 sec

   = 46.15

   = 46 jobs per hour

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Problem 3.7

Answer :

Annual production = 1000000 no of jobs

Machine run = 16 hrs per day , 5 days per week , 50 weeks per year

Cycle time = 1.2 min per job

For 100 %

Machine run time = 16*5*50

=4000 hrs

= 4000 * 60

= 240000 min

1 machine runs for  240000 min

Now for demand = 1000000 / 1.2 min

=833334 min

No of machines required = 833334 / 240000

= 3.47

= 4 (Approximately )

This is for 100 %

For 90 %

We have to increase the no of machine from 4 to 5

For 90 % = 5 machines required

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