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Surface Coatings - Metal

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SURFACE COATINGS - METAL
CUSTOMIZED ENVIRONMENTAL
TRAINING
WELCOME
METAL SURFACE COATING 1/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
INSTRUCTOR
Insert Instructor Name Here
METAL SURFACE COATING 2/66
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OBJECTIVES
пѓѕ Discuss Hazardous Materials Used in Metal Coating and
Coating Removal.
пѓѕ Define VOC and Explain How to Calculate VOC Content.
пѓѕ Discuss the Types of Metal Coatings.
пѓѕ Discuss Transfer Efficiency.
пѓѕ Give an Overview of Application Technology.
пѓѕ Give an Overview of Coating Removal Technology.
пѓѕ Discuss Logs and Recordkeeping.
пѓѕ Recommend Inspection Items.
пѓѕ Discuss Use of Contractors.
METAL SURFACE COATING 3/66
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GOALS
пѓѕ Understand the Hazardous Materials Used in Metal Coating and
Coating Removal.
пѓѕ Understand VOC and Understand How to Calculate VOC Content.
пѓѕ Be Familiar With the Types of Metal Coatings.
пѓѕ Understand How to Improve Transfer Efficiency.
пѓѕ Understand Some of the New Available Application Technologies.
пѓѕ Understand Some of the New Available Coating Removal
Technologies.
пѓѕ Be Familiar With Required Logs and Records.
METAL SURFACE COATING 4/66
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BACKGROUND
пѓѕ In 1998, 61,234 industries reported a total of 7.3 billion
pounds of hazardous chemicals released to the air, land
and water in the United States.
пѓѕ Fugitive Air Emissions, Water Emissions from Poorly
Treated Rinsewater, and Solid Waste Generated from
Coating and Coating Removal Operations can have a
Detrimental Impact on Human Health and the
Environment.
METAL SURFACE COATING 5/66
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LEARNERS
пѓѕ Supervisors
пѓѕ Facility Engineers
пѓѕ Maintenance Personnel
пѓѕ Department Managers
пѓѕ Building Occupants
пѓѕ Process Specialists
пѓѕ Environmental and Safety Committees
METAL SURFACE COATING 6/66
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OVERVIEW
The goal of this course is to provide supervisors
with the tools needed to help reduce hazardous
waste from metal surface coating operations. It
recommends practical, actions that can be carried
out by facility management, maintenance personnel
and building occupants. It also gives an overview of
new technology in coating application and removal.
The course will help you to integrate good surface
coating management activities into your existing
organization and identify which of your staff have
the necessary skills to carry out those activities.
METAL SURFACE COATING 7/66
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WHAT THIS COURSE DOES NOT DO
The course is not intended to provide specific
equipment recommendations for reducing pollution
at your facility. These specialties required training
beyond the intended scope of this course. Where
this expertise is needed, outside assistance should
be solicited.
METAL SURFACE COATING 8/66
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FEDERAL LAWS
пѓј Clean Water Act addresses wastewater effluent
requirements.
пѓј RCRA addresses hazardous waste used in metal
finishing, including minimization
пѓј Clean Air Act Amendments address harmful air
emissions in coatings
 EPA’s Toxic Release Inventory (TRI) requires
businesses to disclose toxic materials at facilities
METAL SURFACE COATING 9/66
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FEDERAL REGULATIONS
Pertinent Regulations:
 40 CFR Part E413 –The Effluent Guidelines and
Standards for Electroplating
 40 CFR Part 59 – National Volatile Organic
Compound Emission Standards for Consumer and
Commercial Products
METAL SURFACE COATING 10/66
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WHY FINISH METALS?
пѓј Without metal finishing, products made from metals
would last only a fraction of their present life-span.
пѓј Metal finishing alters the surface of metal products.
пѓј Industries that use metal finishing in their
manufacturing processes include:
•
•
•
•
•
•
•
•
Automotive
Electronics
Aerospace
Telecommunications
Hardware
Jewelry
Heavy Equipment
Appliances
METAL SURFACE COATING 11/66
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THE POLLUTION PROBLEM
пѓј Of particular importance are those processes that use
highly toxic or carcinogenic ingredients that are difficult
to destroy or stabilize and dispose of in an
environmentally sound manner.
пѓј Some of these processes are:
- Cadmium plating.
- Cyanide-based plating, especially zinc, copper, brass,
bronze and silver plating.
- Chromium plating and conversion coatings based on
hexavalent chromium compounds.
- Lead and lead-in plating.
- Numerous other processes.
METAL SURFACE COATING 12/66
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HAZARDOUS MATERIALS AND
PROCESSES
The metals finishing industry is concerned with pollution
and wastes generated by all processes but especially
those generated by the use of four specific materials in
finishing processes:
(1) the use of cadmium as a plating material,
(2) the use of chromium as a plating material,
(3) the use of cyanide-based electroplating solutions,
(4) the use of copper/formaldehyde-based electroless
copper solutions.
METAL SURFACE COATING 13/66
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CADMIUM
пѓј Cadmium is a common plating material that has
properties superior to other metal coatings in some
applications.
пѓј It displays excellent corrosion resistance and is
valued for its natural lubricity or smoothness.
пѓј It exhibits good corrosion resistance, and meets the
salt-spray test requirements of the automotive industry.
пѓј It can be soldered readily and is toxic to fungus and
mold growth. In the past, numerous military
specifications have specified the use of cadmium.
пѓј The major cadmium complex used in electroplating
baths is cadmium cyanide, or Cd(CN-24).
METAL SURFACE COATING 14/66
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CYANIDE SOLUTIONS
пѓј Sodium and potassium cyanide are used in
electroplating bath formulations for the deposition of
copper, zinc, cadmium, silver, gold, and alloys such as
brass, bronze, and alballoy (copper-tin-zinc).
пѓј Electroplating baths may also utilize cyanide
compounds of the metal being plated, such as copper
cyanide, potassium gold cyanide, or silver cyanide.
пѓј In a well-designed wastewater treatment system,
most cyanides can be destroyed through oxidation.
пѓј Cyanides used in stripping solutions, especially those
for stripping nickel, are similarly resistant to oxidation
and typically must be disposed of in bulk at a high cost.
METAL SURFACE COATING 15/66
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COPPER/FORMALDEHYDE
SOLUTIONS
пѓј Electroless copper deposits are frequently used to
apply a conductive base to non-conductive substrates
such as plastics.
пѓј A thin copper deposit provides a base for an
additional decorative or functional coating of copper,
nickel, etc. One important application is in the coating
of printed circuit boards.
пѓј Formaldehyde, a water pollutant and a suspected
carcinogen, is used as the reducing agent in electroless
copper baths. Caustic mists resulting from hydrogen
evolution and air sparging in the baths present an
additional hazard.
METAL SURFACE COATING 16/66
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CHROMIUM
пѓј Decorative chromium plating is almost always applied
over a bright nickel plated deposit, which in turn can be
easily deposited on steel, aluminum, plastic, copper
alloys, and zinc die castings.
пѓј Functional chromium plating is normally not applied
over bright nickel plating, although in some cases,
nickel or other deposits are applied first to enhance
corrosion resistance.
пѓј The main ingredient in all hexavalent chromium
plating solutions is chromium trioxide (CrO3).
пѓј Hexavalent chromium has been linked to cancer in
humans following prolonged inhalation, and is toxic to
aquatic life at relatively low concentrations.
METAL SURFACE COATING 17/66
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WASTEWATER GUIDELINES
The Effluent Guidelines and Standards for Metal
Finishing (40 CFR Part 433) are applicable to
wastewater generated by any of these operations:
пѓј Electroplating
пѓј Electroless Plating
пѓј Anodizing
пѓј Coating
пѓј Chemical Etching and Milling
пѓј Printed Circuit Board Manufacturing.
Discharges from 40 additional processes, including:
painting, cleaning, polishing, shearing, hot dip coating,
solvent degreasing etc.
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WASTEWATER GUIDELINES
Chemicals to be monitored include:
пѓј Cadmium
пѓј Chromium
пѓј Copper
пѓј Silver
пѓј Zinc
пѓј Cyanide
пѓј Total Toxic Organics (TTOs)
пѓј Oil and Grease
пѓј TSS
пѓј pH
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WASTE HANDLING
пѓј Physical processes such as abrasive
blasting, grinding, buffing, and polishing do not
contribute as much to hazardous waste
generation as chemical and electrochemical
processes.
пѓј The most common hazardous waste sources
are rinse water effluent and spent process
baths. These systems in turn generate solid
and liquid wastes that are regulated under the
provisions of RCRA.
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AIR EMISSIONS
пѓј The air emissions from many metal
finishing processes must be controlled
using scrubbing or filtering equipment.
пѓј These can generate further wastes
that must also be treated, disposed, or
recycled.
пѓј Some of the processing solutions
used in metal finishing have a finite life,
especially conversion coating solutions,
acid dips, cleaners and electroless
plating baths.
METAL SURFACE COATING 21/66
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VOLATILE ORGANIC
COMPOUNDS (VOCs)
пѓј Organic solvents, known as Volatile Organic
Compounds (VOCs) are used in coatings such as paint,
strippers/cleaners, etc.
пѓј In the presence of sunlight, VOCs react in a complex
reaction that produces ozone. Ozone is the major
ingredient in photochemical smog.
пѓј By reducing the amount of VOC in coatings, in
combination with other efforts to reduce VOC
emissions, you can help reduce ozone.
пѓј Most air districts restrict the amount of VOC
emissions allowed.
METAL SURFACE COATING 22/66
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VOC CONTENT
пѓј Coatings consist of solids (resin, pigments, extenders,
additives) and solvents. Solvents lower the viscosity
(reduce or thin), and act as the carrier for the solids.
Solvents also are used to dissolve the solid resin.
Solvents evaporate from the coating before, during and
after application.
пѓј Solvents include VOCs, water, and exempt solvents.
VOC content means pounds of VOCs per gallon of
coating (lb/gal) or grams of VOCs per liter of coating
(G/L), minus water and exempt solvents (exempt solvents
do not contain volatile organic compounds).
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VOC CONTENT
пѓј The VOC concentration does not change if you
increase the volume of mixed paint used, however, the
VOC concentration does increase when adding VOC
solvents such as thinners or reducers.
пѓј Manufacturers are currently being required by federal
regulations to formulate paint to certain VOC
specifications, that when used, according to the
manufacturer’s recommendations, will meet VOC
content limits. The VOC content is generally stated on
the label or on the manufacturer’s paint specification
sheet.
METAL SURFACE COATING 24/66
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CALCULATING VOC CONTENT
Information is from a Material Safety Data Sheet for this
coating:
пѓј If the coating weighs 10.4 pounds/gallon, and it
contains the following VOCs:
Xylene
Toulene
MEK
Mixed Aliphatics
TOTAL
2% x
2% x
6% x
10% x
20% x
10.4 lb/gal = .21 lb/gal
10.4 lb/gal = .21 lb/gal
10.4 lb/gal = .63 lb/gal
10.4 lb/gal = 1.04 lb/gal
10.4 lb/gal = 2.09 lb/gal
2.09 lb/gal x 119.8 (g/L) (gal/lb) = 250 grams/Liter
METAL SURFACE COATING 25/66
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TYPES OF COATINGS
пѓј Water Borne - Water is the major solvent and
includes water reducible and emulsions. These coatings
usually include VOCs as co-solvents.
пѓј UV Curable Coating - Liquid resin and pigment which
uses UV light to cure the coating.
пѓј High Solids - Coatings that contain greater than
normal resin and pigment (70 - 80% by volume).
пѓј Powder - Dry finely ground coating which is usually
sprayed dry on an electrically charged surface and is
later heated to its melting point so that the powder can
flow together (3% VOCs by volume).
METAL SURFACE COATING 26/66
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TYPES OF COATINGS
пѓј Exempt Solvent based - Coatings that contain
exempt solvents, primarily 1,1,1 TCA. These coatings
usually include VOC as stabilizers and co-solvents.
пѓј Electrodeposition - Dip coating process where water
borne coatings are electrically "plated-out".
пѓј Autodeposition - Dipcoat plating process without
electrical charge.
пѓј Catalyzed Coatings - Two or three component
coatings which are mixed together prior to application.
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PHOTOCHEMICALLY REACTIVE
A photochemcially reactive is any solvent with an
aggregate of more than 20% of its total volume
composed of chemical compounds classified below:
a. A combination of hydrocarbons, alcohols,
aldehydes, esters, ethers, or ketones having an
olefinic or cycle- olefinic type of unsaturation: 5%.
b. A combination of aromatic compounds with eight
or more carbon atoms to the molecule except
ethylbenzene: 8%.
c. A combination of ethylbenzene, ketones having
branched hydrocarbon structures, trichloroethylene or
toluene: 20%.
METAL SURFACE COATING 28/66
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TRANSFER METHODS
Coatings and agents containing high VOC
concentrations can be applied using the following high
transfer efficiency methods:
пѓј High-Volume, Low-Pressure coating system
пѓј Electrostatic application
пѓј Flow coat application
пѓј Dip coat application
пѓј Brush coat application
пѓј Pre-packaged aerosol can application
пѓј Roll coat application
METAL SURFACE COATING 29/66
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SPRAY BOOTH FILTERS
пѓј Spray booth filters prevent paint overspray from traveling up
the exhaust vent.
пѓј Filters help increase the life span of the exhaust fans, reduce
fire hazard, and provide protection from the deposition of paint
particles outside the building.
пѓј It is important to maintain your booth to ensure that your
operation does not cause a public nuisance and violate air
regulations.
пѓј Paint overspray can travel through ineffective filters and
damage the finish of automobiles and structures near your
operation. Always make sure that the filters are installed
properly and cover all openings. Remember that the filter media
you use must be designed for your type of spray operations.
METAL SURFACE COATING 30/66
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SPRAY BOOTH FILTER
PRESSURE
пѓј A pressure drop gauge may be
used to determine the pressure
drop across the spray booth
filters.
пѓј As the filter pores become
clogged, the pressure drop
increases.
пѓј Filters should be replaced
according to manufacturer’s
recommendations.
пѓј Check your pressure gauge
frequently for accuracy.
METAL SURFACE COATING 31/66
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KEEP YOUR CURTAIN WET
пѓј Waterwash booths should provide a continuous sheet
of water down the face of the rear booth panel.
пѓј The water sheeting collects the overspray from the
painting operation and the particulates can be skimmed
from the surface of the water for disposal. If the booth
does not provide a continuous sheet of water, i.e. if dry
spots appear, the water spray lines should be checked
for clogged openings. Remove the booth from service
and repair the water lines immediately.
пѓј Never discharge your wastewater to the ground or
storm drain system.
METAL SURFACE COATING 32/66
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TRANSFER EFFICIENCY
пѓј Transfer efficiency is the percentage of paint solids
deposited on the surface of your product. The cost
savings in paint consumption when using high transfer
efficiency guns is significant.
пѓј If you achieve 30% transfer efficiency, then 30% of
the paint solids sprayed have adhered to the product,
and 70% of the paint solids are on your floor, booth
walls, and exhaust filters.
пѓј You can get more paint to stay on the product if you
use application methods with transfer efficiencies in
excess of 65%, and you buy less paint.
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WASTING PAINT
пѓј High transfer efficiency saves paint and decreases
emissions, thus lowering your costs.
пѓј High transfer efficiency decreases your booth filter
purchases, decreases your booth cleaning expenses,
and may decrease your waste disposal costs.
пѓј Train your painters to maximize their efficiency.
пѓј Consider racking parts to make overspray land on a
part.
пѓј Make sure automatic spray lines spray the parts and
not empty hooks.
пѓј Spray corners of parts first so overspray hits
uncoated areas of the part.
METAL SURFACE COATING 34/66
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OPERATING EQUIPMENT
PROPERLY
пѓј Use properly designed equipment
пѓј Eliminate cross drafts
пѓј Reduce air pressure in gun
пѓј Allow dipped parts to drain
пѓј Only spray the part
пѓј For electrostatic painting
- turn on power to electrostatic
- keep a good clean ground
- hook up the grounding strap
METAL SURFACE COATING 35/66
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STORING
пѓј Tightly seal all containers of coatings and solvents.
Cans and drums should be equipped with tight fitting
lids and should remain closed between uses to prevent
evaporation.
пѓј Large drums should have screw caps to cover the
bung holes and should be opened only to empty or fill
the drum. Use a pump or funnel when filling and make
sure to close the drum completely when you are
finished.
пѓј Use new funnels that screw into the bung of drums
and have a lid that clamps down on top of the funnel for
a tight seal.
METAL SURFACE COATING 36/66
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SURFACE PREPARATION
пѓј Preparing a surface may entail
using a solvent degreaser.
пѓј Alternatives to solvent
degreasing include using
abrasives, water with surfactants,
exempt solvents, alkaline washes,
or acid etches.
пѓј Switching from solvent cleaners
to other surface preparation
methods can save money and
reduce disposal costs.
METAL SURFACE COATING 37/66
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FOLLOW MIXING DIRECTIONS
Mixing Directions
пѓј Coating manufacturers will
supply you with instructions
when the coating contains
more than one component.
пѓј Often the coatings must be
mixed with a thinner and a
catalyst.
пѓј Always mix according to the
instructions.
METAL SURFACE COATING 38/66
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CLEANING UP
пѓј VOCs from your facility can be reduced significantly
by cleaning your spray guns and other equipment
properly.
пѓј Never clean your lines by spraying solvents into the
air or into the filters.
пѓј Always direct the clean-up solvents, using minimal
pressure, into containers to prevent evaporation.
Remove atomization tips, soak and/or use a brush to
clean the tip, then flush solvent through the gun (without
the tip) into a container which is immediately sealed.
пѓј Soak spray guns in closed containers and avoid the
use of VOCs for clean-up whenever possible.
METAL SURFACE COATING 39/66
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LOGS
пѓј Keep detailed records of the coatings applied at your
facility. Monthly logs should detail the products
purchased, including the name and number of the
product, and the amount of product purchased, with the
appropriate unit indicated (i.e., gallon, quart, pint).
Remember that inspectors look for accurate records.
пѓј One proven method of record keeping involves the
use of �job tickets’ and a summary log. Many facilities
instruct the operator to record coating information for
each job on a production ticket at the booth. The job
tickets are then summarized nightly by the supervisor.
METAL SURFACE COATING 40/66
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APPLICATION TECHNOLOGY
Non-Cyanide Copper Plating
пѓј Non-cyanide copper plating is an electrolytic process
similar to its cyanide-based counterpart.
пѓј Operating costs for the bath itself are higher for the
non-cyanide process than the cyanide process.
пѓј Non-cyanide copper plating benefits:
•Greatly reduces safety risks to workers.
•Greatly reduces the costs and complexity of treating
spent plating solutions.
•Smaller risk to hydrogen cyanide exposure.
•Plating solution does not have to be treated for
carbonates.
METAL SURFACE COATING 41/66
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APPLICATION TECHNOLOGY
Zinc-Alloy Electroplating
пѓј Both zinc and zinc-alloy electroplating processes are very
common and have a long history in the electroplating industry.
пѓј Recently these processes have been considered as possible
replacements for cadmium coatings.
пѓј Benefits of zinc and zinc-alloy
• Eliminates workplace exposure to cadmium and cyanide.
• Corrosion resistance as good as cadmium.
• Better wear resistance than cadmium.
• Zinc-cobalt deposits show good resistance to atmospheres
containing SO2.
METAL SURFACE COATING 42/66
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APPLICATION TECHNOLOGY
The Blackhole Technology
пѓј Uses an aqueous carbon black dispersion at room temperature
for preparing through-holes in printed wire boards for subsequent
copper in the through-holes.
пѓј Benefits of Blackhole Technology
• Process Simplification - requires fewer process steps as well as
associated chemicals and rinses.
• Contamination Reduction - does not use formaldehyde.
• Ease of Implementation - uses existing equipment in an
electroless copper process line.
• Acceptable Product Quality - accepted under MIL-P-5511OD.
• Lower Operating Costs
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APPLICATION TECHNOLOGY
Ion Vapor Deposition of Aluminum (IVD)
пѓј In IVD, the coating metal is evaporated and partially ionized
before being deposited on the substrate. A typical IVD system
consists of a steel vacuum chamber, a pumping system, a parts
holder, an evaporation source, and a high-voltage power supply.
пѓј Benefits of this technology
• Health and safety risks can be greatly reduced when IVD is used
in place of cadmium electroplating.
• The greatest advantage of aluminum IVD is that the process
significantly reduces the generation of hazardous wastes, and
potentially eliminates the need for special pollution control systems.
METAL SURFACE COATING 44/66
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APPLICATION TECHNOLOGY
Physical Vapor Deposition (PVD)
пѓј A thoroughly cleaned workpiece is placed in a vacuum chamber,
and a very high vacuum is drawn. The chamber is heated to
between 400o and 900o F. A plasma is created from an inert gas
such as argon. The workpiece is first plasma-etched to further
clean the surface. The coating metal is then forced into the gas
phase by either evaporation, sputtering or ion plating.
пѓј Benefits of PVD
• PVD results in a thin, uniform coating that is much less likely to
require machining after application.
• PVD titanium nitride coatings have already gained wide
acceptance in the cutting tool industry.
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APPLICATION TECHNOLOGY
Chromium-free Surface Treatments for Aluminum
and Zinc
пѓј Chromium-free surface treatments for aluminum and
zinc are relatively new.
пѓј One of the few commercially proven, non-chromate
surface treatments for aluminum is an inorganic
conversion coating based on zirconium oxide.
пѓј A recent chrome-free post-rinse process has been
developed for use on phosphated steel, zinc, and
aluminum surfaces prior to painting. The new rinse,
known as Gardolene VP 4683, contains neither
hexavalent or trivalent chrome. It contains only
inorganic metallic compounds as the active ingredient.
METAL SURFACE COATING 46/66
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APPLICATION TECHNOLOGY
Metal Spray Coating
пѓј Molten Metal -The metal is heated by some suitable means
(either resistance heating or a burner) and then supplied to the
atomizing source in molten form.
пѓј Fuel/Oxidant - Oxygen/acetylene flames are typically used.
The metal melts as it is continuously fed to the flame in the form
of a wire or powder.
пѓј Electric arc - In this method an electric arc is maintained
between two wires that are continuously fed as they melt at the
arc.
пѓј These technologies for thermal spraying of metals are well
developed, but they tend to have their own market niche and
are not typically thought of as a replacement for electroplating.
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COATING REMOVAL
TECHNOLOGY
Non-Cyanide Metal Stripping
пѓј Many non-cyanide stripping solutions are typically
proprietary formulations, the detailed chemistry of coating
removal is not known for most solutions.
пѓј Non-cyanide metal strippers have the following benefits:
• Significant potential for reducing waste treatment costs.
• Often easier to recover metals from spent solutions.
• Bath life is longer because higher metal concentrations
can be tolerated.
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COATING REMOVAL
TECHNOLOGY
Plastic Media Blasting (PMB)
пѓј PMB uses low-pressure air or centrifugal wheels to project
plastic media at a surface. The blast particles have sufficient
impact energy, coupled with hardness and geometry to chip
away or erode the coating.
пѓј Some of the major beneficial aspects of PMB include:
• High stripping rate
• Eliminates water use
• Can selectively remove individual coating layers
• Often done with recyclable thermoplastic media
• Fully automated robotic systems available
• Fully developed systems available
• No size limitations on parts to be stripped.
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COATING REMOVAL
TECHNOLOGY
Wheat Starch Blasting
пѓј Wheat starch blasting uses low-pressure air to propel
particles at the painted surface. The coating is stripped
away by a combination of impact and abrasion. Similar
equipment and techniques to PMB.
пѓј Some of the major benefits include:
•Moderate stripping rates can be achieved while
maintaining a gentle stripping action.
•Safe on soft clad aluminum and composites
•Eliminates water use
•Can selectively remove individual coating layers
•Uses inexpensive stripping media
•Media are nontoxic and biodegradable
METAL SURFACE COATING 50/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Burnoff Coating Removal
пѓј Burnoff systems use temperatures of 370oC (700o F) or
higher to volatilize and/or burn the organic coating material.
Inorganic materials such as pigments remaining on the
substrate must be removed by mechanical cleaning such as
low-energy shot blast, manual cleaning, or water rinse.
пѓј Some of the major beneficial aspects include:
•Allows rapid removal of heavy coating accumulation with a
minimum of handling.
•Can process parts with complex shapes.
•Direct-burn ovens can removal wet, uncured coatings.
•Large ovens are available to process large items, but the
maximum size is limited by the oven size.
METAL SURFACE COATING 51/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Molten Salt Coating Removal
пѓј The molten salt stripping process relies on chemical
oxidation of the coating by a specially formulated molten
salt bath. The process uses mixtures of inorganic salts
formulated to react with the coating materials.
пѓј Some of the benefits include:
•Allows rapid removal of heavy coating accumulation
•Provides rapid, well-controlled, uniform heating.
•Wastewater stream is compatible with conventional
wastewater treatment plants.
•Salt baths are available to process moderate sized
items, but the maximum size is limited by the bath size.
METAL SURFACE COATING 52/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Sodium Bicarbonate Wet Blasting
пѓј Compressed air moves the sodium bicarbonate medium
from a pressure pot to a nozzle where the medium mixes
with a stream of water. The blast medium/water mixture,
accelerated to several hundred miles per hour, impacts the
coated surface and shatters into a very fine particulate.
пѓј Benefits include:
• High stripping rate
• Can selectively remove individual coating layers
• Can reduce prewashing and masking of the surface
• Water dissipates the heat generated by abrasive process
and reduces the amount of dust in the air.
• No size limitations on the parts to be stripped.
METAL SURFACE COATING 53/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Carbon Dioxide (CO2) Pellet Cryogenic Blasting
пѓј The carbon dioxide blasting systems have a refrigerated
liquid CO2 supply and a system for converting the liquid to
the solid media used in coating removal. Similar to PMB.
пѓј Benefits of CO2 Pellet Cyrogenic Blasting include:
• CO2 media vaporizes
• Eliminates water use
• Has a clean and well-defined coating removal pattern
• Can selectively remove individual coating layers
• Stripping cleanup requirements typically are minimal
• Equipment can be stripped without requiring disassembly
METAL SURFACE COATING 54/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
High Pressure Water Blasting
пѓј High-pressure waterjet stripping removes coating with a
stream of water projected from specially designed nozzles at
pressures of 15,000 psi to 30,000 psi or more.The coating is
removed by the kinetic impact of the water stream.
пѓј Benefits of high pressure water blasting include:
• The technology has a high stripping rate.
• Stripping water is recycled.
• Wastewater stream is compatible with conventional
wastewater treatment plants.
• There are no size limitations on parts to be stripped.
METAL SURFACE COATING 55/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Medium Pressure Water Blasting
пѓј Medium-pressure water blasting removes coatings with a
stream of water projected from specially designed nozzles at
pressures of 3,000 psi to 15,000 psi. The stripping action
often is supplemented by pre-softening with an alcohol
solvent or by including soft or hard abrasives in the water
stream.
пѓј Some of the benefits include:
• Low implementation cost using simple, robust equipment
• High stripping rates
• Wastewater stream is compatible with conventional
wastewater treatment plants available
• No size limitations on parts to be stripped
METAL SURFACE COATING 56/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
COATING REMOVAL
TECHNOLOGY
Liquid Nitrogen Cryogenic Blasting
пѓј The part to be stripped is cooled by a readily available
cryogenic fluid, liquid nitrogen. Nitrogen is inert, colorless,
odorless, noncorrosive, and noncombustible. Liquid nitrogen
is sprayed on items to be stripped as they rotate on a spindle
within a stainless steel cryogenic chamber. Tensile stresses
thus develop within the coating and make it brittle.
пѓј Benefits of this method include:
• No ash residue
• Low waste volume
• Very fast cycle time (5 to 15 min)
• High throughput rate
• Works well on thick coating buildups.
METAL SURFACE COATING 57/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
RECORDKEEPING
пѓј Accurate recordkeeping helps to ensure that you
operate in daily compliance.
пѓј Daily recordkeeping has several other advantages as
well. Your records tell you how much paint you use each
day. You will have an accurate record of production
expenses which can enable you to cut costs.
пѓј If you have an approved Notice of Construction, it
may include a limitation on annual coating usage. Do
not paint more than you are allowed. Modify your
production schedule to avoid penalties. Be careful with
multiple shifts. If you cannot modify your daily
production, contact your air district.
METAL SURFACE COATING 58/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
SELF- INSPECTIONS
1. If your facility coats light duty automobiles, do the coatings
used have the appropriate/compliant VOC levels?
___Yes ___No ___NA
2. Does your facility only apply coatings with less than 0.1% lead
and hexavalent chromium? ___Yes ___No ___NA
3. If you coatings contain more than 2.1 Lb/Gal or 250 G/L VOC,
do you only use approved application methods as outlined in
your air district’s regulations (i.e. HVLP gun)?
___Yes ___No ___NA
METAL SURFACE COATING 59/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
SELF- INSPECTIONS
4. Does all surface coating take place in a booth or room equipped
with a particulate control system capable of capturing all visible
overspray? ___Yes ___No ___NA
5. Does your paint booth or room exhaust through an unobstructed
vertical stack (no caps, elbows, etc.)? ___Yes ___No ___NA
6. Is your spray gun totally enclosed during clean-up, or is solvent
flushed through the gun into a container which is immediately
sealed? ___Yes ___No ___NA
7. Are all coating and solvent containers tightly sealed when not in
use? ___Yes ___No ___NA
METAL SURFACE COATING 60/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
SELF- INSPECTIONS
8. Are all solvent containing wastes stored in tightly sealed
containers until disposal? ___Yes ___No ___NA
9. Are solvent rags kept in tightly sealed containers when not in
use? ___Yes ___No ___NA
10. Are spills of solvent containing material cleaned up upon
discovery? ___Yes ___No ___NA
11. Are the most current MSDS kept for materials used, and are
they available upon request? ___Yes ___No ___NA
12. Are records of purchases/usages and waste disposal kept for
the previous 24 months of operations and available on site?
___Yes ___No ___NA
METAL SURFACE COATING 61/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
SELF- INSPECTIONS
13. Are fugitive emissions from prep work controlled?
___Yes ___No ___NA
14. Are you properly operating your pressure drop gauge (i.e., is it
checked to insure that it is zeroed before the booth is turned on)?
___Yes ___No ___NA
15. Are filters seated in filter housing such that there are no gaps
between the filter and the housing?
___Yes ___No ___NA
16. If you operate a water wash booth, is the water level
maintained to adequately filter exhaust air?
___Yes ___No ___NA
METAL SURFACE COATING 62/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
SELF- INSPECTIONS
17. If you operate a water wash booth, is the water curain
continuous all the way across the booth wall with no flow
inconsistencies or gaps? ___Yes ___No ___NA
18. Are visible emissions and overspray NOT observed from
the exhaust stack? ___Yes ___No ___NA
19. Are you performing pressure drop readings, filter
changes, visual observations of filter media condition, and
other manufacturer-recommended booth maintenance?
___Yes ___No ___NA
20. Are all maintenance activities recorded on a maintenance
log? ___Yes ___No ___NA
METAL SURFACE COATING 63/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
TIPS FOR USING CONTRACTORS
пѓѕ Remember, You Control Your Facility or Area!
пѓѕ Review Procedures With Them Before Starting the Job!
пѓѕ Ensure They Are Properly Trained!
пѓѕ Determine Their Environmental Compliance Record!
пѓѕ Determine Who Is in Charge of Their People!
 Determine How They Will Affect Your Facility’s
Environmental Compliance!
METAL SURFACE COATING 64/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
ELEMENTS OF A SUCCESSFUL
METAL SURFACE COATING PROGRAM
1. DETAILED WRITTEN METAL SURFACE COATING
INSPECTION GUIDELINES.
2. DETAILED WRITTEN METAL SURFACE COATING BEST
MANAGEMENT PRACTICES.
3. EXTENSIVE EMPLOYEE TRAINING PROGRAMS
4. PERIODIC REINFORCEMENT OF TRAINING
5. SUFFICIENT DISCIPLINE REGARDING IMPLEMENTATION
6. PERIODIC FOLLOW-UP
METAL SURFACE COATING 65/66
В© Copyright Training 4 Today 2001
Published by EnviroWin Software LLC.
THE IMPORTANCE OF A
CLEAN ENVIRONMENT
“I would ask all of us to remember
that protecting our environment is
about protecting where we live and
how we live. Let us join together to
protect our health, our economy,
and our communities -- so all of us
and our children and our
grandchildren can enjoy a healthy
and a prosperous life.”
METAL SURFACE COATING 66/66
В© Copyright Training 4 Today 2001
Carol Browner
Former EPA
Administrator
Published by EnviroWin Software LLC.
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