1Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Information flow

Manufacturing Operation As A Single System

OPERATIONOPERATION

OUTPUTOUTPUT(PRODUCTS)(PRODUCTS)

INPUTINPUT(RAW MATERIALS)(RAW MATERIALS)

CONTROL

2Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Information flow

Manufacturing Operation As A Single System

OPERATIONOPERATION

THROUGPUTTHROUGPUT(Products/Time)(Products/Time)WORK IN PROCESSWORK IN PROCESS

(Units of RAW MATERIALS)(Units of RAW MATERIALS)

CONTROL

CYCLE TIME (Time)CYCLE TIME (Time)

LITTLE`S law: TH=WIP/CTLITTLE`S law: TH=WIP/CT

3Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Sources Of Variability In A Single Operation

Machine Failures

Shut downs due to quality problems

Operator´s Off Times

Slow downs due to set ups

Scheduled maintenance

Tardy arrivals of materials

High Work In Process

Priorities

Recycles

Defective materials

Tardy arrivals

Incomplete lots

Wrong lots

VariabilityVariability

4Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Parameters And Variability Interrelationships

WIPWIP

THTH

CTCT

WoWo

VariabilityVariability

5Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Parameters And Variability Interrelationships

6Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Dependency Phenomenon

2

3

4

1 5Raw materialsRaw materials End ProductsEnd Products

MostDependentOperation

7Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Variability And Dependency Phenomenona Affect:

THROUGHPUT (TH)

WORK IN PROCESS (WIP)

CYCLE TIME (CT)

VARIABILITYVARIABILITY DEPENDENCYDEPENDENCY

8Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Bottleneck Effect

1 2 3

r1 r2 r3

r1 = min (r1,r2,r3) is the bottleneck

Even if W increases as infinite,

TH is TH is maximummaximum r1 r1

ri = Production rate (parts/unit time)ri = Production rate (parts/unit time)

9Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Bottleneck Effect

10Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Global Processing Time:To

1 2 3

t1 t2 t3

Global Processing Time To

To = t1 + t2 + t3To = t1 + t2 + t3

ti = Production time (time per unit)

11Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Critical Wip:Wo

To = Global To = Global Processing Processing

TimeTime

Wo = (rb). Wo = (rb). ToTo

rb = rb = bottleneck bottleneck

raterate

12Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Best Performance Law

W/ToW/To, if W < Wo or W =Wo rbrb, otherwise

ToTo, if W < Wo or W =Wo W/rb, otherwiseCtbest =

Thbest =

13Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Worst Performance Law

THworst = { W/(Wo+W-THworst = { W/(Wo+W-1)}* rb 1)}* rb

CTworst = To + (W-1)/rbCTworst = To + (W-1)/rb

THworst = { W/(Wo+W-THworst = { W/(Wo+W-1)}* rb 1)}* rb

CTworst = To + (W-1)/rbCTworst = To + (W-1)/rb

14Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

AS WIP INCREMENTS

CT INCREMENTS

TH REMAINS EQUAL OR LESSER

15Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

MANUFACTURING PLANNERS

MUST TO KNOW WoWo

IT MEANS THEY HAVE TO KNOW rbrb

BECAUSE Wo = rb.ToWo = rb.To

16Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

WIP MUST BE A WIP MUST BE A CONTROL CONTROL

PARAMETERPARAMETER

17Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

1. TO CONTROL WIP INSTEAD OF TO CONTROL THROUGHPUT

2. TO CONTROL VARIABILITY

18Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

MRP SYSTEMS CONTROL

THROUGHPUT INSTEAD OF CONTROLLING WIP

MRP IS A POWERFUL INFORMATION TOOL

SOME MRP SYSTEMS TREAT TO CONTROL VARIABILITY

19Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

20Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Some Performance Tips

21Luis Ernesto BLANCO RIVERO "SIMULATION AS A TOOL FOR UNDERSTANDING MANUFACTURING"

Animated Simulation Benefits

STUDENTS MAY OBSERVE AND

ANALYZE MANUFACTURING PARAMETERS WHILE SIMULATION

RUNS

STUDENTS MAY CONSTRUCT STEP BY STEP MORE COMPLEX SYSTEMS

STUDENTS LEARN FACTORY PHYSICS BY DOING SIMULATION