Question

(A) The feeder-selector device at one of the workstations of an assembly machine has a
feed rate of 45 components/min and provides a throughput of one part in five. The ideal
cycle time of the assembly machine is 6 sec. The low-level sensor on the feed track is set at
10 components, and the high-level sensor is set at 25 components.

(a) How long will it take
for the supply of components to be depleted from the high-level sensor to the low-level
sensor once the feeder-selector device is turned off?

(b) How long will it take for the components
to be resupplied from the low-level sensor to the high-level sensor, on average,
after the feeder-selector device is turned on?

(c) What are the time proportions that the
feeder-selector device is turned on and turned off?

Answer 1

· Feed Rate=45 Components/Min

· Throughput Of One Part In Five Θ=.20

· Ideal Cycle Time Of The Assembly Machine =6 Sec.

· Components At Low Sensor =10 Components

· Components Set At High Sensor = 25 Components.

(a)

Time to deplete from the high-level sensor to the low-level sensor once the feeder-selector device is turned off

Time to deplete from Nf2 to Nf1

Rate of depletion =cycle rate Rc=60 /6 sec=10 parts/minute

Time to deplete=( components set at high sensor - components at low sensor)/cycle rate

=(25-10)/10

Ans a=1.5 min

(b)

Time to resupply from Nf2 to Nf1

Rate of resupply=fθ-Rc

= feed rate (θ)-cycle rate

=45 x (0.20)-10

= -1 parts/minute

Time to resupply

= components set at high sensor –components at low sensor/ rate of resupply

=(25-10)/-1=15/-1

Ans b=15 min

(c )

Total cycle time for depletion and resupply =1.5 min +15 min (calculated part a+part b)=16.5 minutes

Proportion of time feeder selector is on=15/16.5=0.91 (0.9090)

Proportion of time feeder selector is off=1.5/16.5=0.09 (0.0909)