Question

The Yum and Yee food truck near the business school serves customers during lunch hour by taking orders and making fresh batches of stir-fry. Customers have only one choice during the lunch hour so that Y&Y can maximize the number of customers served. Assume that each customer places just one lunch order, and all lunch orders are the same size: one unit of stir-fry. The stir-fry cooking works in this manner. First, one person cooks a batch of orders in a wok. The cooking depends upon the number of orders in the batch. The time to cook just one order is 3 minutes. For each additional order in the batch, it takes 0.5 minute more to cook. Thus, cooking two orders in a batch takes 3.5 minutes, cooking three orders takes 4 minutes, and so on. The other process is bagging and accepting payments (done by a separate person), which takes 0.80 minute per order.

a. What is the setup time of this process?

b. If Y&Y operates with batch sizes of 6 units, what is their process capacity (in orders per minute)?

c. If Yum and Yee operates with sizes of 10 units, what is the utilization of the work (assume there is sample demand)?

d. Calculate the batch size (in orders) that maximizes the overall flow rate (assume these is sample demand)?

Answer 1

Answer :

a > Setup time : one order processing time - additional order processing time.

: 3.0 - 0.5 = 2.5 Minutes

b >

Batch size on 6 Units

Preparation time for 6 order : 3 + (0.5 * 5) = 5.5 Minutes

Packing time for 6 orders : 6 * 0.8 = 4.8 Minutes

Process Capacity = Capacity of Bottleneck ( Preparation time ) = 6 / 5.5 = 1.09 Orders/Minute

c >

Preparation time for 10 order : 3 + (0.5 * 9) = 7.5 Minutes

Packing time for 10 orders : 10 * 0.8 = 8.0 Minutes

Process Capacity = Capacity of Bottleneck ( Packing time ) = 10 / 8 = 1.25 Orders /Minute

Total time : 15.5 Minutes

Flow Rate = Average Rate = 10/15.5 = 0.65 Orders/Minute

Utilization : (Flow rate / Capacity)*100% = (0.65 / 1.25)*100% = 52%

d>

For Optimal Flow rate : The Preparation time should be equal to the packing time for the number of orders (X) .

Therefore ,

2.5+ (0.5*X) = 0.8*X

or X = 2.5/0.3 = 8.33

Therefore the Optimal order size to maximize the flowrate is - 8.33 Orders per Batch