Environmentally Conscious
Process Planning
Prepared by Felipe Román
Georgia Institute of Technology
Systems Realization Laboratory
1
Last Week… Today
• Last lectures
– Some ECDM assessment tools…
• For processes: process mapping I/O assessment
• For facilities & regions: EnviroFacts & TRI Explorer
• Today
– Begin considering environmental concerns
during the product development process…
particularly in the process planning stage
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Learning Objectives
1. Know what is process planning and how it fits
in the product development process
2. Understand how to carry out environmentally
conscious process planning
3. Learn how to quantitatively assess
manufacturing environmental loads
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Focus: Manufacturing Life Cycle
Stage
Why manufacturing?...
Mining /
Extraction
Environment:
air, sea, land
Disposal
Material
Processing
Product
Manufacture
Demanufacture
Raw material
generation
Remanufacture
Material
Demanufacture
Product
Demanufacture
Energy recovery
Distribution
Recycling
/ Reuse
Use &
Service
Product
Takeback
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Product Development
Product Design
System Design
...
Subsystem
Subsystem
Design 1
Design n
Component
n.1
Component
n.n
...
Process Planning
System Assembly
Process Planning
Subsystem 1 Assembly
Subsystem n Assembly
Process Planning
Process Planning
...
...
Component n.1
Component n.n
Process Planning
Process Planning
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Environmentally Conscious
Manufacturing Strategies
•
•
•
•
•
•
•
•
Good housekeeping
Training and supervision
Waste handling
Material substitution /
elimination / addition
In-process recycling
Process modification
Process Planning
Part / product
modification
Adapted from (Sutherland and Gunter,
2001) and (Skerlos 2005).
Source: http://www.fotosearch.com/ICL154/bim_139/
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Process Planning
Process planning is the set of product development activities that determines how
a part will be manufactured given product and production specifications.
• Also known as…
–
–
–
–
Process engineering
Manufacturing engineering
Process design
Process routing
• Resources
–
–
–
–
Machines
Auxiliary equipments
Cutting tools
Cutting fluids
Figure from Feng and Song, 2000
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Manufacturing Processes
•
•
•
•
Metal Casting
Bulk Deformation / Forming
Sheet Metal Forming
Material Removal
–
–
–
–
Traditional Machining
Precision Machining
Deburring
Advanced Machining
• Surface Preparation
–
–
–
–
Cleaning
Hardening
Electro-plating
Painting
• Joining and Fastening /
Assembly
• Polymer Processing
• Rapid Prototyping
Source:
http://divisions.asme.org/med/enewsletter/2003july/meT
CreportWeb_files/image002.gif. More information can
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be found at http://erc.engin.umich.edu/.
Some Auxiliary Equipment
(Supporting)
•
•
•
•
•
Air compressors
Coolant systems
Water softeners
Water Recirculation
Material/waste
handling
• Chillers
• Boilers
• Piping system
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Some Auxiliary Equipment
(Pollution Control)
•
•
•
•
•
•
Oil/dust mist collectors
Incinerators / oxidizers
Wastewater treatment
Gondolas & roll offs
Chip centrifuges / Chip wringers
Briquetting machines
Source:
http://www.nationalconveyors.com/metal_chip_onl
y/metal_chip_processing/chipwringers6.html
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Source: http://www.ars-inc.com/industrial.htm
Environmentally Conscious
Process Planning
• For traditional machining (turning)…
– Process selection
– Resource selection
•
•
•
•
Machine selection
Auxiliary equipment selection
Cutting fluid selection
Cutting tool selection
– Process parameter, operational sequence
selection
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Turning Process - Lathe
Source: http://www.efunda.com/processes/machining/turn.cfm
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Turning Categories
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Mass & Energy Balances
* Mass & energy balances are your friend…
m 2
Mass balance equation for an open system:
dmcv
  m in  m out
dt
W 2
m 1
m 4
W1
Q 1
CV
m 3
Energy balance equation for an open system:
Q 2
2
2




dEcv
V
V
i
o




 Q  W   min  hin 
 gz i   mout  hout 
 gz o 
dt
2
2




m 5
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Machine-Level Assessment
Elec. = f (x1,x2,x3)
1.
Identify processrelated environmental
Inputs/Outputs (I/Os)
Quantify I/Os
2.
•
•
•
•
•
3.
Electricity (kWh)
Coolant (gals)
Wet chips (lbs)
Used coolant (gals)
Oil mist (mg/m3)
Identify mathematical
relationship / function
for I/Os
electricity
used
coolant
cylindrical
part
coolant (c)
wet
chips
Coolant
System
filtered
coolant
coolant
& chips
Turning
Machine A
heat
wet
machined
part
CV
electricity
oil mist
Mist = f (y1,y2,y3,…)
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Some Machine-Level Models
• Electricity (kWh/yr)
• Coolant (gals/yr)
• Wet chips (lbs/yr)
• Used coolant (gals/yr)
• Oil mist (mg/m3)
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Operational-Level Assessment
Coolant = f (w1,w2,…)
filtered
coolant
cylindrical
part
coolant
& chips
Straight Turning
Operation
heat
Energy = f (z1,z2,…)
wet
machined
part
CV
Cutting
energy
oil mist
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Some Operational-Level Models
For straight turning operations…
• Cutting energy (kWh)
– Cutting force
– Machining time
• Coolant lost from machined part (gals)
– Density of cutting fluid
– Surface tension of cutting fluid
– Cross-sectional area of workpiece
• Oil mist generated from straight turning (mg/m3)
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Different Cleaning Processes
Mechanical
Brushing
Wire
Fiber
Steam-Jet Cleaning
Abrasive
Sand
blasting
Metal shot
Silicon
carbide
Plastic
Corncobs
Nut shells
CO2 pellets
Ice pellets
Tumbling
Vacuum de-oiling
Scrubbing / wiping
Chemical
Aqueous
Solvent
Ultrasonic
Biological
CO2
Pickling
Salt-Bath
Thermal
Acidic
Neutral
Alkaline
Spray
Immersion
Vapordegreasing
Liquid
Supercritical
Burn-off
Plasma
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Aqueous Cleaning Processes
• Direct consumption
Source: http://www.karcher.ca/CCE/HD%20%20HDS%20Web%20Pages/Features/Powe
rNozzle%20Spray%20Others.jpg
• Closed-loop
consumption
Source: http://www.acmefab.com/html_640/PROD_Monorail-washer.html
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Aqueous Cleaning Inputs/Outputs
• Can you think of mathematical models for
estimating these inputs/outputs for a closed-loop
system?
Off-site air
emissions
Electric Energy
Water
Non-electric
Energy
Cleaning Agent(s)
& Chemicals
Cleaned Part(s)
Dirty Part(s)
Basket / Fixture
Wastewater
Cleaning System
Recovered
oil
Sludge
Basket / Fixture
On-site and insite air emissions
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Generic Process Map of an
Aqueous System
Dirty
Part(s)
Machining
Process
Cleaned
Part(s)
Cleaning
System
Dirty
Part(s)
Machining
Process
Cleaning
Agent
Natural Gas /
Coal
Elec.
Air
Compressor
Pressurized Air
Elec. and/
or Gas
Elec.
Steam
Cleaning Machine(s)
Wastewater
Wastewater
Treatment
Treated
Wastewater
Elec.
Soft
Water
Dirty
Water
Dirty Part(s)
Recovered
Oil
Chemicals
Water
Softener
Sludge
Recovered Oil
Cleaned Part(s)
Cleaned Basket/
Fixture
Fugitive emissions / mist
Incinerator
Elec.
Hard
Water
Clean Water
Sludge
Methane
Cleaning
System
Water
Recirculation
Boiler
Dirty Basket/
Fixture
Cleaned
Part(s)
Mist / Ventilation
Exhaust
On-site Air
Emissions
Elec.
Add chemicals and electricity to wastewater treatment
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Summary Main Points
• Showed how to estimate environmental
loads of straight turning operation
• Similar approach should be applicable to
other manufacturing processes (e.g.,
milling, cleaning, etc.)
• By estimating environmental loads &
impacts a process engineer can
(quantitatively) tradeoff cost, quality and
productivity objectives and make better
process planning decisions
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References
1.
2.
Sutherland, J.W. and Gunter, K.L., 2001,
"Environmental Attributes of Manufacturing
Processes," in Handbook of Environmentally
Conscious Manufacturing, C.N. Madu, Kluwer
Academic Publishers, pp. 293-316.
Skerlos, S.J., 2005, "Prevention of Metalworking Fluid
Pollution: Environmentally Conscious Manufacturing at
the Machine Tool, under peer review for textbook," in
Handbook of Environmentally Conscious Mechanical
Design - Volume 2: Environmentally Conscious
Manufacturing, John Wiley & Sons.
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