Ops Management Lecture 2

Question 1

Flow Rate Definition

Answer 1

Rate of output or production rate

Question 2

Flow Time Definition

Answer 2

Time a unit spends in the process as inventory / Total time taken by a unit on average as an inventory

Question 3

Average Inventory (I) formula:

Answer 3

Average Inventory (I) = Flow Time (T) x Flow Rate (R)

Question 4

Cycle Time Definition

Answer 4

Average between two successive completions (Exit)

Question 5

Cycle Time Formula: CT = ?

Answer 5

Cycle Time (CT) = 1 / Flow Rate (R)

Question 6

What is another name for Flow time?

Answer 6

Manufacturing Lead Time (MLT)

Question 7

What is another name for Inventory (I)?

Answer 7

Work In Progress (WIP)

Question 8

MLT is another name for Flow Time. What is MLT formula?
MLT Formula: MLT = _______________

Answer 8

MLT = WIP x Cycle Time (CT)

Question 9

2 criteria for Steady State

Answer 9

1) Average Inflow = Average Outflow
2) Same repeating patterns

Question 10

Formula:

Flow rate = { } ??

Answer 10

Flowrate = Min{ Available Input, Demand, Process Capacity}

Question 11

What is the difference between resource capacity and process capacity?

Answer 11

Resource Capacity: The max amount the resource can produce in a given time unit

Process Capacity: The max amount the process can produce in a given time unit

Question 12

Sequential Process:

Formula for Cycle Time:

Formula for Min Flow Time:

Formula for Process Capacity:

Formula for Max Flow Rate:

Answer 12

Cycle Time: Max{T1,T2….Tn)

Min Flow Time (MLT) : T1 + T2 + T3 …. + Tn

Process Capacity: 1/ Cycle Time

Max Flow Rate = Process Capacity

Question 13

Parallel Processes (Similar):

Formula for Cycle Time:

Formula for Min Flow Time (MLT):

Answer 13

Cycle Time: 1 / (1/T1 + 1/T2 + … 1/Tn)

Min Flow Time = Min {T1,T2, …. Tn}

MLT uses minimum as they are not unique tasks, but multiple same assembly lines (E.g. Packing, Customer Service at Starhub)

Question 14

Parallel Processes (Different):

Formula for Cycle Time:

Formula for Min Flow Time (MLT):

Answer 14

Cycle Time: Max {T1,T2,…,Tn}

Min Flow Time: Max {T1,T2,…,Tn}

SAME formula and using MAX as they are completely different activities in the processes (E.g. Washing inside and outside of an airplane; Two different tasks which must both be completed before proceeding).

Question 15

How to Compute WIP from Gantt Chart?

Answer 15

1) Identify Repetitive patterns for each resource in the gantt chart
2) In each such pattern, Identify:
- The total duration of that pattern (Total Time)
- Time for which the resource is working on the job unit (Working Time)
3) Then, WIP = Working Time / Total time