Week 1 - 2 Flashcards

1
Q

Machine

A

hardware that performs job (sometimes called tool)

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2
Q

Workstation

A

collection of one or more identical machines

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3
Q

Part

A

component that moves through workstations

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4
Q

Process

A

specific job or task adding value to a part

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5
Q

Processing time

A

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

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6
Q

Throughput TH

A

avg. quantity of parts produced per unit time

TH best
= w/T𝟎 (w <= W𝟎)
= r (w > W𝟎)

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7
Q

Cycle Time CT

A

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)

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8
Q

Science of Maufacturing

A

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

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9
Q

Science offers

A

Basics
- Quantitative relationship

Intuition
- Tool for determining approaches to pursue

Synthesis
- Proving unified framework

Science for figure out root causes of β€œwaste”

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10
Q

Descriptive Model

A

Define object with fundamental principles or general laws

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

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11
Q

Prescriptive model

A

Provides detailed methods for decision making

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

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12
Q

Two essentials of Maf. System

A
  • Demand

- Transformation

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13
Q

Variability

A

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

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14
Q

Buffers

A

excess resource that corrects misalignment (absorbing variability)

Time: delay between demand and satisfaction

Capacity: extra transformation potential

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15
Q

Inventory Buffer

A

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

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16
Q

Time Buffer

A

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

17
Q

Capacity Buffer

A

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

18
Q

Efficient Frontier

A

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

Inefficient: Better position is possible

19
Q

Raw Material Inventory (RMI)

A

Stock point at the beginning of process

20
Q

Finished Goods Inventory (FGI)

A

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

21
Q

Routing

A

Sequence of workstations passed through by a part

22
Q

Customer order

A

A request from a customer for a part (Demand)

23
Q

Work in Process (WIP or WIP inventory)

A

Inventory between the start and endpoints of a product routing

24
Q

Jobs

A

A set of physical materials that traverses a routing together

25
Yield rate (or yield)
Amount of usable outputs over the total outputs
26
Setting objectives:
1. Find out current position | 2. consider customer relationship (time sensitivity)
27
Bottleneck rate π‘Ÿ
Maximum throughput rate (Capacity) of the workstation having highest long term utilization A routing can’t accept parts more than bottleneck rate
28
Utilization
arrival rate / effective production rate Portion of time a WS actually performs over the total available time
29
Raw process time ( π‘‡πŸŽ)
average time it takes a single job to traverse the empty line
30
Critical WIP (W𝟎)
π‘ŠπŸŽ = π‘Ÿπ‘‡πŸŽ WIP level when a line with no variability achieves maximum throughput (π‘Ÿ) with minimum cycle time 𝑇
31
Little's Law
WIP = TH * CT parts = (parts/hr) * hr
32
Worst Case Law
- Variability in processing time CT worst = w*T𝟎 TH worst = 1/T𝟎
33
Practical Worst Case
Assumption: 1. Single machine at workstation 2. Balanced line 3. Variability that all WIP configurations are equally likely
34
Practical Worst Case Law
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)