Process Flow Diagram: Ex4: Making Potato Chips

1. Process Flow Diagram: Ex4: Making Potato Chips • Raw potatoes are first washed and peeled. Then the potatoes are sliced and fried in a large kettle. After frying, the cooked chips are inspected and any burnt ones are removed. The chips are then salted and stored in large cartons before they are packaged. The chips are packaged in either one-ounce or eight-once packages. Draw a process flow diagram. Raw potatoes yes Burnt or not? Wash and peel Remove Slice and fry Inspect 1 oz Package 1 oz or 8 oz? Salt cartons Package 8 oz Slide #8

2. Ex2: Expanding the Bottleneck • What is the bottleneck? What is the system capacity? Measure mozzarella = 167 pizzas / hr • If you were to invest in adding capacity to the bottleneck only, what would you do? Increase system capacity to 175 pizzas / hr (2nd lowest capacity). That means, increasing mozzarella station to 175(.24) = 42 lbs/hr After that, both become bottleneck and both must be expanded in order to have higher process capacity • How do you increase system capacity to 250 pizzas/hr? Measure mozzarella: increase to 250(.24) = 60 lbs/hr Apply sauce: increase to 250 pizzas/hr Apply plastic overwrap: increase to 250*2.7 = 675 sq-ft/hr Measure romano: increase to 250(.12) = 30 lbs/hr Apply cheese: increase to 250 pizzas/hr. Slide #19

3. Ex3: Flowchart Treatment by senior doctors 30% No Greet & Question by nurse Simple? patients pay yes 70% Treatment by junior doctors To represent possible waiting, a triangle can be added before each of the following activities: “Treatment by sr. dr.”, “Treatment by jr. dr.”, and “pay” Slide #21

4. Ex3: Capacity calculations Capacity unit to use: # of incoming patients per hour Capacity of “nurse” stage = 2*12 = 24 inc. patients / hr Capacity of “senior doc” stage = 3*2/0.3 = 20 inc. patients / hr Capacity of “junior doc” stage = 6*4/0.7 = 34.3 inc. patients / hr Capacity of “cashier” stage = 1*30 = 30 inc. patients / hr The bottleneck stage is “senior doctors” stage. The throughput rate of the system is 20 inc. patients per hour. Slide #22

5. Ex4: Restaurant Example Capacity Calculations • Comparable unit = # of incoming customers (inc. cust.) per hour Parking = 100 cars * 2.2 (customers/car) / {1.5 hrs} = 146.7 inc. cust./hr. Bar Area = 80 seats / {1.5 hr * 0.2 (bar customers/inc. customer)} = 266.7 inc. cust. / hr. Dining Area = 170 seats / {1.5 hr * 0.8 (dining cust/inc. cust.)} = 141.7 inc. cust. / hr. Cooking Area = 150 meals / {1hr*( 0.2(0.4) + 0.8(1.0)) meals/inc. customer} = 170.5 inc. cust. / hr. Dining area is the bottleneck Slide #24

6. Ex4: Expanding Bottleneck What is the bottleneck? What is the system capacity? Dining Area; system capacity = 141.7 inc. cust. / hr. If you were to invest in adding capacity to the bottleneck only, what would you do? Increase capacity to 146.7 inc. cust./hr (2nd lowest capacity). This means, increasing # of seats to (146.7/141.7)*170 = 176, i.e. adding 6 seats (e.g. add 3 tables of two). [Alternatively, assume the number of seats should be x, then (x/1.5)/0.8 = 146.7. This implies x = 176 seats] How do you increase system capacity to 180 inc. cust. /hr? Dining: (180/141.7)*170 = 216  add 46 seats Parking: (180/146.7)*100 = 122.7  add 23 parking spaces Cooking area: (180/170.5)*150 = 158.4 meals / hr  add chefs or/and space Slide #25