manufacturing processes 2.83 and 2 - mitweb.mit.edu/2.813/www/class slides/lecture 8 mfg... ·...
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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