Module 1 - Process Design and analysis (Part 3)

Question 1

(Review)

Name, explain and give units of the 3 flow measures

Answer 1

Flow time (Units of Time): Total time that a flow unit spends in an activity/process
Inventory (#): Number of flow units in an activity/process at any point of time
Throughput(#/Unit of time): Number of flow units through an activity/process per unit of time

Question 2

(review)

What is little’s law?

Answer 2

Inventory (L) = Throughput (lambda) x Flow time(W)

Question 3

(3 already seen, 2 new one)

now name the 5 process flow measures

Answer 3

• Flow time
• Inventory
• Throughput
• Cycle time (UT): Average time between two consecutive flow units exiting an activity/process, which is working continuously
• Capacity (#/UT): Throughput of an activity/process if it is working continuously

Capacity -> Think of these as the maximum
potential of the process, not what it is actually doing

Question 4

What is the relaitonship with the Cycle time and the capacity?

Answer 4

Cycle time = 1/ Capacity

Question 5

If a machine worked continuously, it would produce
5 units per hour. What is the cycle time of this machine?

Answer 5

• Capacity: 5 units per hour
• Cycle time = 1/5 hour = 12 minutes

Question 6

A restaurant has 100 seats and an average customer spends 15 minutes in the restaurant. What is the restaurant’s capacity? In other
words, what is the maximum rate at which the restaurant can serve customers?

Lambsa =

Answer 6

The maximum inventory of the restaurant is L=100 customers and the customer’s flow time is W=1/4 hr. Therefore, by using Little’s Law, the capacity of the restaurant is:

Lambda = L/W = 100/(1/4) = 400 per hour

Question 7

Associate questions to the concept of the measures of process performance:

How long does it take to produce a product?
How many units can the process produce during a given time interval?
What is the level of work-in-process inventory?

Answer 7

How long does it take to produce the product?
* Flow time: the time spent by a unit in the system
How many units can the process produe during a given time interval?
* Capacity: the maximum rate at which output can be created given an infinite supply of inputs
* Cycle time: the time between two successive product completions when the process is operations at capacity
What is the level of work-in-process inventory?
* Inventory: the number of units in the process at a given time

Question 8

What is the capacity of the bottleneck/ what is the bottleneck?

Answer 8

Capacity of the process = capacity of the bottleneck

Important: Holds when different activities use different ressources

The bottleneck resource for a single product process is the resource with the lowest capacity or highest cycle time

Question 9

What is a ressource

Answer 9

A resource is any person, place or thing which is required in order for an activity to run

Question 10

What are the 2 concepts represented in a Gantt chart?

Answer 10

Activities and ressources

Question 11

How to do the bottleneck analysis?

Answer 11

1. List activities, times and resources
2. Group the activities performed by each resource
3. Capacity analysis for each resource
4. Capacity of process = Capacity of the resource with the smallest capacity

Question 12

Go and redo the exercise of kristen cookies case!

Question 13

Key takeaways!

Answer 13

Process concepts
* Performance measures: Capacity, Cycle time, Flow time, Bottleneck
* Gantt Chart
How to analyze a process?
* Little’s Law
* Bottleneck resource determines process capacity - bottlenecks can shift
** How to improve a process?**
* Increase the bottleneck resource (add an oven)
* Pool the bottleneck reosurce with some non-bottleneck resources
* Change the batch size
* Eliminate some non-bottleneck ressources