Manufacturing Processes 2.83 and 2 - MITweb.mit.edu/2.813/www/Class Slides/Lecture 8 Mfg... · 2006. 3. 15. · Material Removal Rate 20.0 cm 3/sec 4.7 cm 3/sec 5.0 cm 3/sec 1.2 cm

machining

sand castinginjection molding

Manufacturing Processes2.83 and 2.813

Readings

• a) Thiriez, “An Environmental Analysis of Injection Molding”,IEEE 2006 Abstract. (click here for PDF).

•

• b) Gutowski, “Electrical Energy Requirements for Manufacturing Processes”, CIRP 2006. (click here for PDF)

•

• c) Williams, E. et al, “The 1.7 Kilogram Microchip”, Enviro. Sci. Technol. 36, 2002, p 5504-5510.

• http://web.mit.edu/2.813/www/files/Williams%201.7kg%20microchip.pdf

•

• also see the comment and reply to this article (Use VERA):

• Environmental Science and Technology 2004, 38, pp1915-1917

Outline

• Energy use in the mfg sector

• Mfg Processes

– machining

– casting

– injection molding

– general energy model

– semiconductors

Individual Process Energy Flow

ENERGY

Process

Waste Heat

Waste Materials (embodied energy)

Materials (embodied energy)

Materials (embodied energy)

Exa = 10 18

Efficiency, 0 ≤ η ≤ 1

input work available actual

needed work availablemin :Efficiency Law 2nd

input

waste-input

input

output useful :Efficiency Law1st

II =

==

η

η

Examples (using best values):

gas furnace heating

c → t ….. = .94

electric heating

c → t → m → e → t

(.94)(.425)(.935)(.93)= .347

machine tool

c → t → m → e → m

(.94)(.425)(.935)(.935)= .349

Smil

Trends in Mfg Efficiency

Reuse

Remanufacture

Reclaimed Heat

Extraction

SOURCES

SINKS

Inputs Directly from the Environment

•Water •Air •Sun •Earth

Input Materials

•Energetic materials

•Raw Materials ( φ)Ep

•Recycled Materials (1 -φ)Er

1 kg

Use

Recycle

Outputs Directly to the Environment

•Emissions •Pollutants •Particulates •Water •Noise •Solid Waste •Waste heat

Manufacturingγ

1+α+γ

α

β

Em

Er , E’’p

Energy Conversion

•Electrical •Heat

•Chemical •Mechanical

•Reclaimed heat

E’p

Primary and secondary energy

requirements for materials

Chapman and Roberts

Primary

Production

φ

(1-φ)

Secondary

Production β

γ

Er

Ep

Em

1+α+γ

α

Manufacturing

1 kg

Primary

Production

φ

(1-φ)

Secondary

Production β

γ

Er

Ep

Em

1+α+γ

α

Manufacturing

1 kg

γ)βα(Eγ)α(φ)E(φEE mprieq ++++++−+= 1 1 )1( sec

Manufacturing reaches both up and

down stream

γ)βα(Eγ)α(φ)E(φEE mprieq ++++++−+= 1 1 )1( sec

material energy requirement

mfg energyrequirement

some processes

can use recycled material

process wastes require more

material input

process wastes require more

process energy

some process

wastes can be

recycled

Machining (service Vs product)

Mining Primary Mfg Distribution Use Disposition

Machining: system boundaries

Tool

Preparation

contaminated

cutting fluid

raw stock or

net-shape

partsscrap, chips,

cutting fluid,

spent tooling

dirty parts

cutting fluid

clean

cutting

fluid

water

clean parts

additives

Cutting Fluid

Preparation

Cleaning

spent cleaner,

wastewater, soil

Material

Production

useable

toolingcleanersenergy

spent fluid,

wastewater, chips

energy

water energy

energy

ore

Machine Tool

Construction

machine

tools

cutting oil

Material

Removal

Inventory from LCI software183 Solved organics Water kg 0.000000316 x 0.000000316

184 Solved substances Water kg 0.0000272 x 0.0000272

185 Strontium Water kg 0.0000017 x 0.0000017

186 Sulfate Water kg 0.00031 x 0.00031

187 Sulfur Water kg 4.75E-09 x 4.75E-09

188 Sulfur trioxide Water kg 2.62E-08 x 2.62E-08

189 Suspended substances, unspecified Water kg 0.0000313 x 0.0000313

190 Tin, ion Water kg 7.89E-10 x 7.89E-10

191 Titanium, ion Water kg 0.00000383 x 0.00000383

192 TOC, Total Organic Carbon Water kg 0.0000225 x 0.0000225

193 Toluene Water kg 2.17E-08 x 2.17E-08

194 Tributyltin Water kg 1.45E-09 x 1.45E-09

195 Tungsten Water kg 6.4E-10 x 6.4E-10

196 Vanadium, ion Water kg 0.000000323 x 0.000000323

197 Xylene Water kg 1.73E-08 x 1.73E-08

198 Zinc, ion Water kg 0.000000649 x 0.000000649

199 Aluminium waste Waste kg 1 1 x

200 Production waste, not inert Waste kg 0.000888 x 0.000888

201 Waste, final, inert Waste kg 0.0152 x 0.0152

202 Waste, nuclear, high active/m3 Waste m3 4.43E-11 x 4.43E-11

203 Waste, nuclear, low and medium active/m3 Waste m3 9.98E-09 x 9.98E-09

204 Heat, waste Soil MJ 0.000467 x 0.000467

Machining Comparisons

Data from Gutowski et al 2004, Kordonowy 2002, Kalpakjian 1995, Machinery’s Handbook 1996.

Energy Breakdown

Constant start-up operations (idle)

Run-time operations (positioning, loading, etc)

Material removal operations (in cut)

Energy Requirements

Constant start-up operations (idle)

Run-time operations (positioning, loading, etc)

Material removal operations (in cut)

Machine Use Scenario

Arbitrary Number of work hours

Machine uptime

Machine hours (idle, positioning, or in cut)

Percentage of machine hours spent idle

Machine hours spent idle

Active machine hours per 1000 work hours

Machining Scenario

Percentage of machine hours spent positioning

Machine hours spent positioning

Percentage of machine hours spent in cut

Machine hours spent in cut

Energy Use per 1000 work hours

Constant start-up operations (idle)

Run-time operations (positioning, loading, etc)

Material removal operations (in cut)

Total energy use per 1000 work hours

Energy Used per Material Removed

Material Machined

Material Removal Rate 20.0 cm3/sec 4.7 cm

3/sec 5.0 cm

3/sec 1.2 cm

3/sec

Material removed per 1000 work hours 40824000 cm3

9593640 cm3

4212000 cm3

1010880 cm3

Energy used/Material removed 14.2 kJ/cm3

60 kJ/cm3

2.3 kJ/cm3

10 kJ/cm3

kWh

35%

315 hours

351 hours

40%

13.2%

20.2%

65.8%

1.2

Aluminum Steel Aluminum Steel

160996 kWh 2744 kWh

6237 kWh

kWh

673 kWh

10335471 kWh

1038 kWh149288

567 hours 234 hours

70%

243 hours

60%30%

810 hours 585 hours

90 hours

10%

900 hours900 hours

90% 90%

1000 hours 1000 hours

22 kW 5.8 kW

kW

1.8

166 kW

6.8 kW kW

11.3%

3.5%

Production Machining Center (2000)

85.2%

Automated Milling Machine (1998)

Energy requirements at the

machine tool

Jog (x/y/z) (6.6%)

Machining (65.8%)

Computer and Fans (5.9%)

Load

Constant

(run time)

(20.2%)

Variable

(65.8%)

Tool Change (3.3%)

Spindle (9.9%)

Constant

(startup)

(13.2%)

Carousel (0.4%)

Unloaded Motors (2.0%)

Spindle Key (2.0%)

Coolant Pump (2.0%)

Servos (1.3%)

Jog (x/y/z) (6.6%)

Machining (65.8%)

Computer and Fans (5.9%)

Load

Constant

(run time)

(20.2%)

Variable

(65.8%)

Tool Change (3.3%)

Spindle (9.9%)

Constant

(startup)

(13.2%)

Carousel (0.4%)

Unloaded Motors (2.0%)

Spindle Key (2.0%)

Coolant Pump (2.0%)

Servos (1.3%)

Production Machining Center Automated Milling Machine

From Toyota, and Kordonowy 2002.

Improving machining

%5

2.14

/700

2.14

3

3

3

=≅=

cm

kJ

cmJ

cm

MJ

workplasticIIη

• increase speed

• reduce hydraulic actions

• turn off aux equipment

• multiple cutting heads…

Specific energy, uS

Hence we have the approximation;

Power = Hardness * MRR

MRR is the Material Removal Rate or d(Vol)/dt

Since Power isP = F * V

and MRR can be written as,d(Vol)/dt = A * V

Where A is the cross-sectional area of the undeformed chip, we can get an estimate for the cutting force as,

F = H × A

Note that this approximation is the cutting force in the cutting direction.You may want to use the specific cutting energy “us” given in Table 20.1 of Kalpakjian in place of the Hardness value in the above equations.

Basic Machining Mechanism

The average power plant in the United States is 35% efficient.

Machining as a product

50% of the energy from the

grid comes from coal

• electricity from the US grid comes with

– 667 kg of CO2/MWh

– 2.75 kg of SO2/MWh

– 1.35 kg of NOx/MWh

– 12.3 g Hg/GWh

– etc……..

Data from US Energy Information Administration, DOE 2002 & Klee & Graedel

annual SUV equivalents

Electric Grid CharacteristicsHydro Nuclear Other Coal Oil Gas

Waste/

Renewable

Overall

Efficiency

Austria 65 0 0 11.1 3.6 17.2 3.1 43.1

Belgium 1.6 56.9 0 23.9 1.7 14.4 1.5 29.9

Denmark 0 0 2.2 74.2 10.9 10.7 2.1 39.2

Finland 17.2 28.1 0 31.7 1.9 12.3 8.9 45.4

France 13.7 77.5 0.1 6 1.5 0.8 0.4 30.2

Germany 4.8 28.9 0.4 54.6 1.4 8.6 1.3 30.1

Greece 10.6 0 0 69.1 20 0.3 0 26.6

Italy 19.3 0 1.7 10.3 47.9 20.5 0.2 32.2

Netherlands 0.1 5 0.7 31.7 4.6 55.8 2.1 32.5

Norway 99.2 0 0 0.2 0 0.3 0.3 65.4

Portugal 43.2 0 0 36.5 17.4 0 2.9 37.9

Spain 23.5 32.3 0.2 31.4 8 3.9 0.7 32.6

Sweden 36.9 52.5 0.1 3 5.2 0.3 2 40.5

Switzerland 52.4 44.3 0 0 0.5 1 1.7 37.6

United Kingdom 1.4 27.2 0.1 42.2 4 23.5 1.6 29.1

United States 7.1 19.6 0.0 50.7 3.1 16.7 2.2 29.3

Percentage of Gross Electricity genereated from different fuels

and Overall Efficiency of the Electric Grid (including distribution)

in 1993 in different European countries [Boustead PVC] and in 2003 in the U.S. [EIA 2004].

annual SUV equivalents

USSweden

the fine print

• Assumptions:

Annual emissions resulting from the operation of a typical production machine tool

(22 kW spindle, cutting 57% of the time, 2 shifts, auxiliary equipment, electricity from US grid)

as measured in annual SUV equivalents (12,000 miles annually, 20.7 mpg)

• CO2 – 61 SUV’s

• SO2 – 248 SUV’s

• NOx – 34 SUV’s

Sand Casting

Process Material Flow

Metals Flow

Sand+ Flow

Pouring Cooling TrimShakeout

Mixing

Product FinishingMelting

Mold Formation

Sand Cooling

Sand Processing (AO Treatment)

Recycling

Recycling

Product & Waste

Losses

A. Jones

Sand casting; boundaries

S. Dalquist

Sand casting; energy profile

• National statistics

• averages 6 to 12 MJ/kg (at the factory) of saleable cast metal

• Melting largest component

S. Dalquist

Nat’l statistics Vs model

• pour Vs part size ~ 2 to 3

• thermal energy

∆H = mCp∆T+m∆Hf => 0.95 (aluminum), 1.3 MJ/kg (cast iron)

• furnace efficiency, 0.6<η<0.8

• melt energy

≈ 3 to 6 (model) Vs 2.9 to 6.7 (statistics)

Casting Energy Example

6.0Electricity losses

10.7Total at foundry

MJ/kgStage

16.7TOTAL

1.2Finishing

0.7Casting

5.8Metal preparation

3.0Mold preparation

Source: DOE, 1999.Source: EIA, 2001.

Metals used in Casting

• Iron accounts for 3/4 of

US sand cast metals

– Similar distribution in the

UK

– Share of aluminum

expected to increase with

lightweighting of

automotive parts

• Sand used to castings

out– about 5.5:1 by mass

• Sand lost about 0.5:1 in

US; 0.25:1 in UK

Source: DOE, 1999.

Improving sand casting

%715

1

15

≅≅∆+∆

=

kg

MJ

hTC pIIη

• reduce pour size

• improve furnace efficiency

• use waste heat

• use fuel Vs electricity

Aggregate TRI data (toxic releases)

Sandcasting Emissions Factors

• Emissions factors are useful

because it is often too time

consuming or expensive to

monitor emissions from

individual sources.

• They are the best way to

estimate emissions if you do

not have test data.

*S= % of sulfur in the coke. Assumes 30% conversion of sulfur into SO2.

Source: EPA AP-42 Series 12.10 Iron Foundries

http://www.epa.gov/ttn/chief/ap42/ch12/bgdocs/b12s10.pdf

0.1Baghouse

0.005 - 0.07--0.5Uncontrolled

Electric Induction

0.3Baghouse

0.05- 0.60.6S*736.9Uncontrolled

Cupola

LeadSO2

COTotal ParticulateProcess

Iron Melting Furnace Emissions Factors

(kg/Mg of iron produced)

Source:AFS Organic HAP Emissions Factors for Iron Foundries

www.afsinc.org/pdfs/OrganicHAPemissionfactors.pdf

0.285EPA average core

0.5424AFS average core

0.643AFS heavily cored

Emissions FactorCore Loading

Pouring, Cooling Shakeout Organic HAP Emissions Factors

for Cored Greensand Molds

(lbs/ton of iron produced)

TRI Emissions Data – 2003

XYZ Foundry (270,000 tons poured)

262,191262,11774074

ZINC (FUME OR

DUST)

1,152,8891,145,5857,300TOTALS

7,4848356,64556,640PHENOL

14.60.2514.35014.35MERCURY

768,709768,38732248274MANGANESE

39,69239,52516740127LEAD

2020000DIISOCYANATES

74,77874,70178969COPPER

Total waste

Managed (lbs)

Total transfers off

site for waste

Management (lbs)

Total on-site

Release (lbs)

Surface

Water

Discharge (lbs)

Total Air

Emissions (lbs)Chemical

Injection Molding*

* Source: http://www.idsa-mp.org/proc/plastic/injection/injection_process.htm

*

Schematic of thermoplastic Injection molding machine

Injection Molding

2.813 Spring 2006

Gutowski & Thiriez

Yes, this is how

LEGOS are

made!!!

Click here for

an injection

molding

animation!!!

Or:

http://www.popan

dco.com/archive/

moab/moab.swfhttp://www.wired.com/news/images/full/lego-car_f.jpg

CRADLE

Polymer Delivery

Injection Molding

Emissions to air, water, & land

Scrap

Note to Reader: FACTORY GATE

= Also included in the Paper

Polymer

Delivery

Naphtha, Oil.

Natural Gas

Ancilliary Raw

Materials

Thermoplastic Production (Boustead)

Internal Transport

Additives

Compounder

Pelletizing

Building (lights,heating, ect..)

Energy Production Industry

Anciliary Raw

Materials

Emissions to

air, water, &

land

Internal Transport Drying

= Focus of this Analysis

Waste Management

Drying

Building (lights,heating, ect..)

Packaging

Injection Molder

Extrusion

Service Period

1 kg of Injection Molded Polymer

Emissions

to air,

water &

land

Emissions

to air,

water &

land

Polymer ProductionLargest Player in the Injection Molding LCI

Sources HDPE LLDPE LDPE PP PVC PS PC PET

Boustead 76.56 77.79 73.55 72.49 58.41 86.46 115.45 77.14

Ashby 111.50 ------- 92.00 111.50 79.50 118.00 ------- -------

Patel ------- ------- 64.60 ------- 53.20 70.80 80.30 59.40

Kindler/Nickles

[Patel 1999]------- ------- 71.00 ------- 53.00 81.00 107.00 96.00

Worrell et al.

[Patel 1999]------- ------- 67.80 ------- 52.40 82.70 78.20

E3 Handbook

[OIT 1997]131.65 121.18 136.07 126.07 33.24 ------- ------- -------

Energieweb 80.00 ------- 68.00 64.00 57.00 84.00 ------- 81.00

What is a polymer:

How much energy does it take to make 1 kg of polymer = a lot !!!

Values are in MJ per kg of polymer produced.

Polymer Production

energy requirements for materials

production (per cm3)

CRADLE

Polymer Delivery

Injection Molding

Emissions to air, water, & land

Scrap

Note to Reader: FACTORY GATE

= Also included in the Paper

Polymer

Delivery

Naphtha, Oil.

Natural Gas

Ancilliary Raw

Materials

Thermoplastic Production (Boustead)

Internal Transport

Additives

Compounder

Pelletizing

Building (lights,heating, ect..)

Energy Production Industry

Anciliary Raw

Materials

Emissions to

air, water, &

land

Internal Transport Drying

= Focus of this Analysis

Waste Management

Drying

Building (lights,heating, ect..)

Packaging

Injection Molder

Extrusion

Service Period

1 kg of Injection Molded Polymer

Emissions

to air,

water &

land

Emissions

to air,

water &

land

Compounding and Extrusion

• An extruder is used to mix additives with a polymer base, to bestow the polymer with the required characteristics.

• Similar to an injection molding machine, but without a mold and continuous production.

• Thus it has a similar energy consumption profile (3 – 6 MJ/kg)

Environmentally Unfriendly Additives:

•Fluorinated blowing agents (GHG’s)

•Phalates (some toxic to human

liver, kidney and testicles)

•Organotin stabilizers (toxic and

damage marine wildlife)

Driers• Used to dry internal moisture in hygroscopic polymers and external

moisture in non-hygroscopic ones.

• It is done before extruding and injection molding.

W150

W200

W300

W400

W600

W800

W1000

W1600

W2400

W3200

W5000

R2 = 0.8225

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 500 1000 1500 2000 2500 3000 3500

Throughput (kg/hr)

Power Trendline

Specific Power Consumption

(MJ/kg)

km

PSEC

m

E

m

P+===

&&

0

Source: [Thiriez]

Same as

CRADLE

Polymer Delivery

Injection Molding

Emissions to air, water, & land

Scrap

Note to Reader: FACTORY GATE

= Also included in the Paper

Polymer

Delivery

Naphtha, Oil.

Natural Gas

Ancilliary Raw

Materials

Thermoplastic Production (Boustead)

Internal Transport

Additives

Compounder

Pelletizing

Building (lights,heating, ect..)

Energy Production Industry

Anciliary Raw

Materials

Emissions to

air, water, &

land

Internal Transport Drying

= Focus of this Analysis

Waste Management

Drying

Building (lights,heating, ect..)

Packaging

Injection Molder

Extrusion

Service Period

1 kg of Injection Molded Polymer

Emissions

to air,

water &

land

Emissions

to air,

water &

land

Injection molding cycle;

1) Melt, 2) Inject, 3) Hold, 4) Eject

Source:

http://cache.husky.ca/pdf/br

ochures/br-hylectric03a.pdf

Machine Types:• Hydraulic

– One or more hydraulic pumps to power all of the machine’s motions.

– Inefficient: idle power & extra transfer of work (pump � hydraulic fluid � mechanical motion)

• All-electric

– Servo motors power � mechanical drives

– Superior efficiency

– Not a good for high clamping forces

• Hybrid

- ex: electric screw & hydraulic clamp

All-electric vs. hybrid

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14Time (seconds)

Power Required (kW)

MM 550 Hybrid NT 440 All-Electric

PlasticizeInject high

Clamp open-close

Inject low

ton

Cool

Ton

Buildup

The hydraulic plot would be even higher than the hybrid curve

Source: [Thiriez]

For Hydraulics and Hybrids as throughput

increases, SEC � k.

0

1

2

3

4

5

6

7

8

0 50 100 150 200Throughput (kg/hr)

SEC (MJ/kg) F

HP 25

HP 50

HP 60

HP 75

HP 100

Low Enthalpy - Raise Resin to Inj. Temp - PVC

High Enthalpy - Raise Resin to Inj. Temp - HDPE

Variable Pump Hydraulic Injection Molding Machines.

Enthalpy value to melt plastics is just 0.1 to 0.7 MJ/kg !!!

Does not account for the electric grid. Source: [Thiriez]

Clamping (52%) [5280 W]

Hydraulic Motors (25.6%) [2690 W]

Heaters (5.0%) [530 W]

Computer and Fans (0.5%) [50 W]

Clamping Force

Transformer (5.5%) [580 W]

Injection (7.3%) [770 W]

Feed (5.9%) [620 W]

Constant

(run time)

(13.2%)

Variable

(50.2%)

Constant

(startup)

(36.6%)

Clamping (52%) [5280 W]

Hydraulic Motors (25.6%) [2690 W]

Heaters (5.0%) [530 W]

Computer and Fans (0.5%) [50 W]

Clamping Force

Transformer (5.5%) [580 W]

Injection (7.3%) [770 W]

Feed (5.9%) [620 W]

Injection (7.3%) [770 W]

Feed (5.9%) [620 W]

Constant

(run time)

(13.2%)

Variable

(50.2%)

Constant

(startup)

(36.6%)

Constant

(run time)

(13.2%)

Variable

(50.2%)

Constant

(startup)

(36.6%)

Source: [Kordonowy 2002]

Idling

Power

(Fixed)

Engel Machine @ LMP

All-electrics have very low fixed energy costs (small

idling power). SEC is constant as throughput increases.

vpSEC ≈

0

1

2

3

4

5

6

7

8

9

0 5 10 15 20Throughput (kg/hr)

All-Electric - 85 tons

Hydraulic - 85 tons

SEC (MJ/kg)

Material: PP

Source: [Thiriez]

HDPE LLDPE LDPE PP PVC PS Consumed Inj. Molded PC PET

avg 89.8 79.7 73.1 83.0 59.2 87.2 81.2 74.6 95.7 78.8

low 77.9 79.7 64.6 64.0 52.4 70.8 69.7 62.8 78.2 59.4

high 111.5 79.7 92.0 111.5 79.5 118.0 102.7 97.6 117.4 96.0

avg

low

high

avg

low

high

avg

low

high

avg

low

high

0.990.09

-----

Thermoplastic Production

Generic by Amount Extras

Building (lights,

heating, ect..)Pelletizing

Polymer Delivery

0.19

Compounder

0.24

Internal

Transport

0.19

0.12

0.24

Polymer Delivery

3.57

3.25

8.01

0.30 1.82

5.001.62

Extrusion

0.70 0.16

-----

0.06 -----

0.31

Subtotal

0.12

-----

5.51

Drying

ENERGY CONSUMPTION BY STAGE in MJ/kg of shot

LCI Summarized Results

avg

low

high

avg

low

high

avg

low

high

avg

low

high

avg

low

high

Notes Drying - the values presented assume no knowledge of the materials' hygroscopia. In order words, they are

averages between hygroscopic and non-hygroscopic values. For hygroscopic materials such as PC and PET

additional drying energy is needed (0.65 MJ/kg in the case of PC and 0.52 MJ/kg in the case of PET)

DryingInternal

Transport

3.11 1.80

1.62

-----0.30

-----

Building (lights,

heating, ect..)

0.99

-----

0.04 0.70

69.46

117.34

7.35 6.68

124.18

87.87 87.20

70.77

Hybrid All-Electric

93.60

Subtotal

TOTAL w/

Generic Inj.

Molded

Polymer

71.65

178.68

Hydraulic

72.57

-----

13.08

5.35

11.29

3.99

69.79

5.56 4.89

Hydraulic Hybrid All-Electric

Injection Molding - Choose One

19.70 26.54

4.47 3.17

11.22 18.06

8.45 15.29

Injection Molder

TOTAL w/o

Polymer Prod

18.97

81.04

Granulating - a scarp rate of 10 % is assumed

Pelletizing - in the case of pelletizing an extra 0.3 MJ/kg is needed for PP

13.24 12.57

8.84 7.96 6.66

Injection Molding

(look below)Scrap (Granulating)

0.05

0.03

0.12

Source: [Thiriez]

Energy Production Industry

The Grid is about 30% efficient

Hydro Nuclear Other Coal Oil Gas

Waste/

Renewable

7.1% 19.6% 0.0% 50.7% 3.1% 16.7% 2.2%

United States Electricity Composition by Source

For every MJ of electricity we also get for free:

�171.94 g of CO2

�0.76 g of SO2

� 0.31 g of NOx

� 6.24 g of CH4

� 0.0032 mg of Hg

Scale

6 Main Thermoplastics

Compounder and Injection

Molder

4.01E+08

2.06E+08 6.68E+08

U.S.

GJ/year

9.34E+07

Global

All Plastics

GJ/year

HDPE,

LDPE,

LLDPE,

PP, PS,

PVC

The Injection Molding Industry in the U.S. consumes 6.19 x

107 GJ of electricity (or 2.06 x 108 GJ in total energy).

This is larger than the electric production of Nicaragua or

Panama.

In such a scale imagine what a 0.1 % energy savings mean !!!

Improving injection molding

%5.220

5.

20

=≅∆+∆

=

kg

MJ

hTC pIIη

• reduce cycle time

• improve heating efficiency

• use waste heat

• replace hydraulic actions

with electric

•reduce secondary operation

General electric energy model General electric energy model General electric energy model General electric energy model for mfg processesfor mfg processesfor mfg processesfor mfg processes

vkPP &+= 0

Po

wer

(kW

)

Process Rate (cm3/sec)

Process Rate (cm3/sec)Specific

Energ

y (

MJ/c

m3)

kv

P

v

E o +=&

physics

auxiliary equipment & infrastructure

Thiriez

SEC vs. Throughput

Variable Volume Hydraulic Machines

0

1

2

3

4

5

6

7

8

0 50 100 150 200Throughput kg/hr

SEC (MJ/kg)

HP 25

HP 50

HP 60

HP 75

HP 100

Low Enthalpy - Raise Resin to Inj. Temp - PVC

High Enthalpy - Raise Resin to Inj. Temp - HDPE

thermal oxidative treatment

Murphy

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E+12

1.E-07 1.E-05 1.E-03 1.E-01 1.E+01 1.E+03

Process Rate [cm3/s]

Injection Molding Machining Finish Machining

CVD Sputtering Grinding

Abrasive Waterjet Wire EDM Drill EDM

Laser DMD Oxidation Upper Bound

Lower Bound

Ele

ctr

icity R

equirem

ents

[J/c

m3 ]

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E+12

1.E-07 1.E-05 1.E-03 1.E-01 1.E+01 1.E+03

Process Rate [cm3/s]

Injection Molding Machining Finish Machining

CVD Sputtering Grinding

Abrasive Waterjet Wire EDM Drill EDM

Laser DMD Oxidation Upper Bound

Lower Bound

Ele

ctr

icity R

equirem

ents

[J/c

m3 ]

Range in

machining

from roughing

to finishing

kW cm3/s J/cm

3

10.76 3.76E+00 3.41E+03 ----

26.10 9.77E+00 3.21E+03 ----

71.40 5.05E+01 1.96E+03 ----

35.76 1.40E+01 3.09E+03 ----

47.46 2.70E+01 2.30E+03 ----

65.34 4.51E+01 1.99E+03 ----

12.73 7.66E+00 2.20E+03 ----

13.17 1.09E+01 1.75E+03 ----

51.41 4.25E+01 1.75E+03 ----

194.80 2.00E+01 1.42E+04 ----

194.80 4.70E+00 6.00E+04 ----

10.65 5.00E+00 3.50E+03 ----

10.65 1.20E+00 1.50E+04 ----

2.80 1.50E+00 4.90E+03 ----

2.80 3.50E-01 2.10E+04 ----

75.16 4.01E-01 1.87E+05 a [15, 16]

Finish

Machining9.59 2.05E-03 4.68E+06 a [15, 16]

16.00 6.54E-05 2.44E+08 ---- [6]

15.00 3.24E-03 4.63E+06 b [17]

14.78 9.63E-04 2.66E+07 b [18]

25.00 1.65E-03 1.52E+07 d [19]

6.75 1.05E-05 6.45E+08 b

19.50 3.25E-04 6.01E+07 b

5.04 6.70E-04 7.52E+06 ---- [17, 20]

7.50 2.85E-02 3.08E+05 b [21, 22]

10.00 1.66E-02 6.92E+04 ---- [21]

16.00 1.04E-02 1.58E+06 ----

16.00 8.01E-02 2.06E+05 ----

8.16 1.14E-02 7.15E+05 a

8.16 5.15E-03 3.66E+06 a

14.25 2.23E-03 6.39E+06 ---- [12, 24]

6.60 2.71E-03 2.44E+06 c [25]

Drill EDM 2.63 1.70E-07 1.54E+10 b [26, 27]

Laser DMD 80.00 1.28E-03 6.24E+07 b [15]

21.00 8.18E-07 2.57E+10 d

48.00 4.36E-07 1.10E+11 d

Notes/Assumptions:

a =

b =

c =

d =

Power required is equal to rated power since the

machine is operating at maximum throughput.

Oxidation

Power required is assumed to be 75% of

rated power.

If both idle and run power are provided, the

machine is assumed to run 100% of the time.

.

[6]

[9]

Required power is back-calculated from SEC (in

MJ/kg or J/cm3) and throughput (cm

3/s).

[14]

[23]

Grinding

Waterjet

Wire EDM

CVD

Sputtering[17]

Machining

Injection

Molding

Estimates

Process Name

Power

Required

Process

Rate

Electricity

Required NoteRefe-

rences

cutting tools and machining times

Mechanisms of exergy loss

• degradation of working materials (oxidation and

other reactions)

• degradation of auxiliary materials (oxidation and

other reactions)

• mixing

• loss and/or disposal of working and auxiliary

materials

Table 3 Preliminary, Order of Magnitude estimates for Material Exergy Transformation in Manufacturing Processes

Inefficient use of O2

>100XThermal oxidation

Excess coverage, inefficient

use of gases

>100%>100%CVD

All cut material lost, all

abrasive lost

~100X~100%Abrasive Waterjet

Minor losses~1%~2%Die Casting & Injection

Molding

All material residue to waste,

wire to recycle

~2%~100%EDM

Oxidation, mixing, loss of

abrasive grit

~2%~10%Grinding

Minor oxidation, mixing, cutting

fluid loss

~1%~1%Machining

CommentAuxillary Material LossWorking Material LossProcess

Preliminary Estimates

Exergy lost/Exergy of material

processed

1. machining

2. grinding

3. electrical discharge

4. waterjet

5. sand casting

6. die casting

7. injection molding

8. chemical vapor

1. ≈ 0.01 -0.02

2. ≈ 0.1 - 0.2

3. ≈ 0.90

4. ≈ 100.0

5. ≈ 0.1

6. ≈ 0.02

7. ≈ 0.02

8. ≈ 1.0 and up

Preliminary Estimates

Injection Molding

Machining

CVD

Grinding

Waterjet

Wire EDM

Sand Casting

Die Casting

Oxidation

Finish machining

Drill EDM

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

Exergy Lost/Exergy of Material Processed

Electricity Requirement [J/cm3]

Electronics Fabrication Processes

• References

– Williams, E. et al, The 1.7 Kilogram Microchip,

– Kuehr, R, and Williams, E. “Computers and

the Environment” Kluwer Press 2003

– Murphy, C. F. Electronics, in “Environmentally

Benign Manufacturing” Gutowski et al 2001

available at http://web.mit.edu/ebm/

1.7 kg microchip

Williams et al

Materials and Environmental

Concerns - Integrated Circuits

Wafer fabrication

Product materials: Si, SiO2, Al, ± CuEBM Issues: Water, energy, gas emissions (especially PFCs - perfluoro compounds)

Chip packaging

Product materials:Polymers, Ceramics, Ni/Au alloys, Cu, Au

EBM Issues: Energy, metal-bearing liquid waste, flame retardants, material waste

C. Murphy

Production of Hyper-Pure Silicon

Extraction

Reduction to Silicon

Metal

SiO2 + C → Si + CO2

Conversion to

Trichlorosilane,

distillation

Si + 3HCl →

HSiCl3 + H2

CVD to produce

polycrystalline Si

(Polysilicon)

HSiCl3 + H2 →

Si + 3HCl

Formation of

monocrystalline

Si ingot

Cutting and

polishing to

produce Si

wafers

S. Paap

Czochralski crystal pulling

1.7 kg microchip

Williams et al

1.7 kg microchip

Williams et al

Williams et al

Materials and Environmental

Concerns - Printed Wiring

Boards

PWB fabrication

PWB (board-level) assembly

Product materials: Ceramic, epoxy-glass, or other polymers; Cu, Pd, Pb, Au

EBM Issues: Water, energy, flame retardants, Pb finishes, plating solutions

Product materials: Pb/SnEBM Issues: Energy, Pb

C. Murphy

Materials and Environmental

Concerns - Computer System

Product materials: NiCdEBM Issues: Cd, life/efficiency

CRT

Batteries

Storage Media

Final Assembly

Product materials: Glass, Pb, phosphors, steel, Al, CuEBM Issues: Energy, Pb

Product materials: Al or glass, Ni, MgEBM Issues: recyclability

Product materials: Al or glass, Ni, MgEBM Issues: recyclability

C. Murphy

Materials Inventory for Fabrication of a 15.5

kg monitor and a 9 kg CPU.

Kuehr and Williams

Homework #5

1. What is the eco-footprint of a foundry that produces 270,000 tons of cast iron each year?

2. Estimate the toxic emissions to air for a sand cast 1kg part (use TRI data).

3. Compare the energy for sand casting a steel part that is 0.5 kg and machining this same part from a 1 kg block of aluminum.

4. Compare the energy consumed from making a 24.5 kg computer to the sand casting of a 24.5 kg cast iron part.

5. How does the XYZ foundry compare with the national TRI data?

be sure to state all assumptions