Week 1 - 2

Question 1

Machine

Answer 1

hardware that performs job (sometimes called tool)

Question 2

Workstation

Answer 2

collection of one or more identical machines

Question 3

Part

Answer 3

component that moves through workstations

Question 4

Process

Answer 4

specific job or task adding value to a part

Question 5

Processing time

Answer 5

time to takes to perform task on a machine (without waiting time)

Question 6

Throughput TH

Answer 6

avg. quantity of parts produced per unit time

TH best
= w/T𝟎 (w <= W𝟎)
= r (w > W𝟎)

Question 7

Cycle Time CT

Answer 7

avg. time between release of job at the beginning until it reaches inventory point at the end of routing

CT best
= T𝟎 (w <= W𝟎)
= w/r (w > W𝟎)

Question 8

Science of Maufacturing

Answer 8

Science is essential: describes nature with simple but powerful model
-> Requiring descriptive model to explain nature in factory

Question 9

Science offers

Answer 9

Basics
- Quantitative relationship

Intuition
- Tool for determining approaches to pursue

Synthesis
- Proving unified framework

Science for figure out root causes of “waste”

Question 10

Descriptive Model

Answer 10

Define object with fundamental principles or general laws

Understanding relationship among Understanding relationship among inventory, cycle time, throughput, capacity, variability

Question 11

Prescriptive model

Answer 11

Provides detailed methods for decision making

develop based on descriptive m, to design and control for objectives

Question 12

Two essentials of Maf. System

Answer 12

• Demand

- Transformation

Question 13

Variability

Answer 13

Demand and transformation is subject to variation
causing misalignment

-> essential to understand cause of variability and how to deal with it for an efficient system

Question 14

Buffers

Answer 14

excess resource that corrects misalignment (absorbing variability)

Time: delay between demand and satisfaction

Capacity: extra transformation potential

Question 15

Inventory Buffer

Answer 15

Extra material in transformation process or between it and demand process
-> storage / land cost

Question 16

Time Buffer

Answer 16

a delay between a demand and satisfaction of it by the transformation
process
-> customer satisfacftion

Question 17

Capacity Buffer

Answer 17

Extra transformation potential needed to satisfy irregular or unpredictable demand rates
-> investment cost

Question 18

Efficient Frontier

Answer 18

Infeasible (under curve): Defined by the state of art technology

Inefficient: Better position is possible

Question 19

Raw Material Inventory (RMI)

Answer 19

Stock point at the beginning of process

Question 20

Finished Goods Inventory (FGI)

Answer 20

Stock point where end Item is held prior to shipping to the customer

Question 21

Routing

Answer 21

Sequence of workstations passed through by a part

Question 22

Customer order

Answer 22

A request from a customer for a part (Demand)

Question 23

Work in Process (WIP or WIP inventory)

Answer 23

Inventory between the start and endpoints of a product routing

Question 24

Jobs

Answer 24

A set of physical materials that traverses a routing together

Question 25

Yield rate (or yield)

Answer 25

Amount of usable outputs over the total outputs

Question 26

Setting objectives:

Answer 26

1. Find out current position

2. consider customer relationship (time sensitivity)

Question 27

Bottleneck rate 𝑟

Answer 27

Maximum throughput rate (Capacity) of the workstation having
highest long term utilization

A routing can’t accept parts more than bottleneck rate

Question 28

Utilization

Answer 28

arrival rate / effective production rate

Portion of time a WS actually performs over the total available time

Question 29

Raw process time ( 𝑇𝟎)

Answer 29

average time it takes a single job to traverse the empty line

Question 30

Critical WIP (W𝟎)

Answer 30

𝑊𝟎 = 𝑟𝑇𝟎

WIP level when a line with no variability achieves maximum
throughput (𝑟) with minimum cycle time 𝑇

Question 31

Little’s Law

Answer 31

WIP = TH * CT

parts = (parts/hr) * hr

Question 32

Worst Case Law

Answer 32

• Variability in processing time

CT worst = w*T𝟎
TH worst = 1/T𝟎

Question 33

Practical Worst Case

Answer 33

Assumption:

1. Single machine at workstation
2. Balanced line
3. Variability that all WIP configurations are equally likely

Question 34

Practical Worst Case Law

Answer 34

E. processing time single machine
{1 + (w-1) / N } * t

E. proc. time (=CT) of production line:
CT = {1 + (w-1) / N } * Nt
= T𝟎 + (w-1) / r

E. Throughput:
TH = WIP/CT
= w*r / (W𝟎 + w-1)