Dixie Industrial Finishing Company

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Dixie Industrial Finishing Company

• 4925 S. Royal Atlanta Drive
• Tucker, GA 30084
• [phone]
• Jim Jones Vice President
• Terry Windham, CEF Sales/Quality

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PLATING What is it?

• Also called electroplating, plating is the
  mechanically bonding of one metal to another for
  the purpose of corrosion protection, decorative
  appeal, hardness, electrical conductivity,
  reflectivity, and/or wear resistance
• In a nut shell, plating modifies the surface
  properties of the base metal to make it more
  suitable for its intended use

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Typical Properties AchievedThrough Plating

• Corrosion resistance
• Appearance
• Abrasion resistance
• Value (silver/gold, etc)
• Solderability
• Rubber Bonding

• Electroforming
• Electrical Resistance
• Reflectivity
• Diffusion Barrier
• Lubricity
• High Temp. Resistance

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CRITICAL STEPS IN PLATING

• Racking/Loading (position, number of parts)
• Amperage (amount of current for the number of
  parts)
• Cleaning (strength, temperature, time)
• Pickling/Acid (strength, temperature, time)
• Rinsing (time, flow of water, cleanliness)
• Plating process (Zn, Ni, Sn, Ag, Au, etc.)
• Chromates (strength, pH, temperature, time, age
  of chromate)
• Post-dips (strength, age, temperature, pH)

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Typical Zinc Plating Cycle
SOAK CLEANER
ELECTRO- CLEANER
RINSE
ACID
RINSE
Direction of Work Flow
PLATING TANK

• Multiple, counterflow rinses usually used
• Pre-dips, post treatments. etc., may be used

RINSE
BRIGHT DIP
Direction of Work Flow
OTHER CHROMATE
BRIGHT DIP RINSE
CHROMATE RINSE
HOT RINSE
DRY
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What happens to steel?

• Steel is the cheapest structural material
  available for countless uses
• However, steel is not very resistant to corrosion
  (red rust)

Red Rust
Steel Part (Unplated)
Rust damages (pits) the surface of the base metal
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The Plating Tank
ZINC BALLS
(-)


Cathode
Anode
Anode
Zn
Zn
(-)
Zn
Zn
PART
Zn
(-)
Zn
Zn
Zn
Zn
Zinc Plating Solution
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What happens to zinc?

• Zinc metal will corrode (white corrosion) if not
  protected by a chromate finish
• As the zinc corrodes, it fails to protect the
  base metal and red rust of the base metal occurs

White corrosion
Zinc Plating
Steel Part
Rust damages (pits) the surface of the base metal
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ZINC PLATED PART
Chromate Finish
Plated Metal (Zinc)
Steel Part

• The part is protected from corrosion by the zinc
  plating
• The zinc plating is protected from corrosion by
  the chromate finish

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TYPES OF CHROMATES

• Hexavalent
• - Clear
• - Yellow
• - Bronze
• - Black
• - Olive Drab / Green

• Trivalent
• - Blue Bright (Clear)
• Thin Film
• - Non-hex thick film passivates (non-colored,
  black). Can be dyed.

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Hexavalent Chromates

• Excellent corrosion protection properties
• Fairly inexpensive
• Easy / fast to apply _at_ room temperature
• Variety of colors
• Self-healing properties
• Can not be baked
• Carcinogenic / health issues
• Considered environmentally non-friendly (do not
  meet ELV, RoHS, WEEE requirements)

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Why the elimination of hexavalent chromium?

• To meet the requirements of ELV, RoHS and WEEE
  directives
• Hexavalent chromium is carcinogenic by nature.
  Hexavalent chromium compounds can slip through
  cell membranes and react with DNA causing cell
  mutations/cancer
• Hexavalent chromium is a strong oxidant that
  poses a threat to biological systems

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ELV

• Extended Life Vehicle (ELV)
• Directive 2000/53/EC
• Pb, Hg, Cd, Cr6 Banned from automotive coatings
  as of 7-2007
• Objective prevention of waste from vehicles plus
  reuse, recycle, recovery of end-of life
  vehicles components. 85 recycled by 2006, 95
  by 2015
• Vintage historic vehicles are exempted
• Components, materials, as well as spare
  replacement parts are also covered
• Automotive component manufacturers to provide
  appropriate information to treatment facilities,
  concerning dismantling, reuse

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WEEE

• WEEE
• EC Directive on Waste from Electrical and
  Electronic Equipment
• 2002/96/EC Jan 2003
• Required all 25 EU member states to implement
  into law within 18 months (Aug 2004) a
  requirement that appliances and electrical
  devices be manufactured in such a manner that
  they can be recycled/recovered at a recovery rate
  of 70-80 based on type of appliance.
• As of 8-05 all EU members except Malta and UK had
  at least a framework regulation.

WEEE Man represents 3.3 tons of electronic waste
generated by each citizen of the UK in a lifetime
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RoHS

• RoHS
• Restriction of Hazardous Substances in Electrical
  and Electronic Equipment (RoHS)
• Directive (2002/95/EC)
• As of July 1, 2006, this directive bans lead,
  mercury, cadmium, hexavalent chromium,
  polybrominated biphenyls (PBBs) and
  polybrominated diphenyl ethers (PBDEs) from all
  new electrical and electronic equipment sold to
  EU companies and manufactured in the EU.

Computer Hardware is Subject to RoHS
Directive Automotive Hardware is Subject to ELV
Directive
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WEEE and RoHS Product Categories

• Large appliances
• Small appliances
• IT/telecom equipment
• Consumer equipment
• Lighting equipment
• Electrical/electronic tools
• Toys, sport equipment
• Medical equipment
• Monitoring/control equipment
• Automatic dispensers

Excluded by RoHS Directive
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Business Issues for Surface Finishers/Manufacturer
s

• WEEE and RoHS Directives signal new trend toward
  product regulation.
• Customers increasingly want to know the material
  content and planned end-of-life disposition for
  products they buy.
• Achieve legal compliance
• Promotegreen procurement
• Corporate sustainability
• Respond to stakeholders

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Non-Hexavalent Passivates
Cons

• More expensive (contain expensive tri-chromium
  compounds, organic acids, and other metals)
• Must be heated to apply (typically 140oF)
• Slower to apply (increases cycle time)
• Not self healing (require additional top coats
  for protection more expense)
• Lower corrosion protection than hexavalents
  (without topcoats/seals)
• Less color variety (non-colored black)

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TYPICAL SALT SPRAY HOURS

• Clear Trivalent 12 24 hours
• Clear Hexavalent 20 32 hours
• Black Hexavalent 72 hours
• Yellow Hexavalent 96 hours
• Olive Drab / Green 168 hours
• Non-hexavalent thick film 72 hours
• Non-hexavalent black 36 72 hours
• (all results are without seals/topcoats)

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Topcoats / Seals

• There are a variety of topcoats / seals
  available. Silicated dips, polymers/lacquers,
  cross-linking polymers, lubricating seals
  (torque-n-tension compounds)
• Silicated dips offer some self-healing help and
  increase corrosion protection. These are very
  thin and will not cause dimensional problems
  with fasteners

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Topcoats / Seals(cont.)

• Polymers / lacquers offer enhanced corrosion
  protection as well as scratch resistance
• Polymers / lacquers can pose some conductivity
  issues
• Polymer / lacquer films can be thick and may
  cause fit/dimensional issues in fasteners,
  especially in threaded areas
• Lubricating seals (torque-n-tension) offer
  enhanced corrosion protection, some self-healing
  help, and lubricity, changing torque values of
  the surface (automotive fastener requirements).
  These seals can be expensive to apply.

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THANK YOU!

• A big thanks to you for allowing us the
  opportunity to share this information with you
  today.
• For questions or comments, we can be reached at
• Dixie Industrial Finishing Company, Tucker, GA
• www.dixie-industrial.com
• Jim Jones (770 908-7900)
• jim_at_dixie-industrial.com
• Terry Windham [phone]
• terryw_at_dixie-industrial.com