Dixie Industrial Finishing Companydixiefinishing.com/wp-content/uploads/plating.pdf · Dixie Industrial Finishing Company 4925 S. Royal Atlanta Drive Tucker, GA 30084 (770) 934-7100

Dixie Industrial Finishing Company

4925 S. Royal Atlanta Drive Tucker, GA 30084

(770) 934-7100

Jim Jones –Vice President Terry Windham, CEF – Sales/Quality

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

Typical Properties Achieved Through Plating

" Corrosion resistance

" Appearance " Abrasion

resistance " Value (silver/gold,

etc) " Solderability " Rubber Bonding

" Electroforming " Electrical

Resistance " Reflectivity " Diffusion Barrier " Lubricity " High Temp.

Resistance

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)

Typical Zinc Plating Cycle

SOAK CLEANER

ELECTRO- CLEANER RINSE ACID RINSE

PLATING TANK

RINSE

BRIGHT DIP

OTHER CHROMATE

BRIGHT DIP RINSE

CHROMATE RINSE HOT RINSE DRY

Direction of Work Flow

Direction of Work Flow

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

What happens to steel? • Steel is the cheapest structural material

available for countless uses • However, steel is not very resistant to

corrosion (red rust)

Steel Part (Unplated)

Red Rust

Rust damages (pits) the surface of the base metal

The Plating Tank

PART

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

ZINC BALLS + + (-)

(-)

(-)

Cathode Anode Anode

Zinc Plating

Solution

What happens to zinc?

Steel Part

• 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

Rust damages (pits) the surface of the base metal

Zinc Plating

White corrosion

Steel Part

Plated Metal (Zinc)

Chromate Finish

ZINC PLATED PART

• The part is protected from corrosion by the zinc plating

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

TYPES OF CHROMATES

v Hexavalent - Clear - Yellow - Bronze - Black - Olive Drab /

Green

v Trivalent - Blue Bright (Clear) *Thin Film - Non-hex thick film

passivates (non-colored, black). Can be dyed.

Hexavalent Chromates

n  Excellent corrosion protection properties n  Fairly inexpensive

n  Easy / fast to apply @ room temperature n  Variety of colors

n  Self-healing properties n  Can not be baked

n  Carcinogenic / health issues n  Considered environmentally non-friendly

(do not meet ELV, RoHS, WEEE requirements)

Why the elimination of hexavalent chromium?

o To meet the requirements of ELV, RoHS and WEEE directives

o Hexavalent chromium is carcinogenic by nature. Hexavalent chromium compounds can slip through cell membranes and react with DNA causing cell mutations/cancer

o Hexavalent chromium is a strong oxidant that poses a threat to biological systems

ELV Extended Life Vehicle (ELV) n  Directive 2000/53/EC

n  Pb, Hg, Cd, Cr+6 Banned from automotive coatings as of 7-2007

n  Objective: prevention of waste from vehicles plus reuse, recycle, & recovery of end-of life vehicles & components. 85% recycled by 2006, 95% by 2015

n  Vintage & historic vehicles are exempted

n  Components, materials, as well as spare & replacement parts are also covered

n  Automotive component manufacturers to provide appropriate information to treatment facilities, concerning dismantling, & reuse

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

WEEE Man represents 3.3 tons of electronic waste generated by each

citizen of the UK in a lifetime

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.

RoHS

Computer Hardware is Subject to RoHS Directive

Automotive Hardware is Subject to ELV Directive

WEEE and RoHS Product Categories

1.   Large appliances 2.   Small appliances 3.   IT/telecom equipment 4.   Consumer equipment 5.   Lighting equipment 6.   Electrical/electronic tools 7.   Toys, sport equipment 8.   Medical equipment * 9.   Monitoring/control equipment * 10.   Automatic dispensers

*Excluded by RoHS Directive

Business Issues for Surface Finishers/Manufacturers

n  WEEE and RoHS Directives signal new trend toward “product regulation.”

n  Customers increasingly want to know the material content and planned end-of-life disposition for products they buy. •  Achieve legal compliance •  Promote“green procurement” •  Corporate sustainability •  Respond to stakeholders

Non-Hexavalent Passivates

Ø  More expensive (contain expensive tri-chromium compounds, organic acids, and other metals)

Ø  Must be heated to apply (typically 140oF) Ø  Slower to apply (increases cycle time) Ø  Not self healing (require additional top coats

for protection – more expense) Ø  Lower corrosion protection than hexavalents

(without topcoats/seals) Ø  Less color variety (non-colored & black)

Cons:

TYPICAL SALT SPRAY HOURS

v Clear Trivalent 12 – 24 hours v Clear Hexavalent 20 – 32 hours

v Black Hexavalent 72 hours v Yellow Hexavalent 96 hours v Olive Drab / Green 168 hours

v Non-hexavalent thick film 72 hours v Non-hexavalent black 36 – 72 hours

v (all results are without seals/topcoats)

Topcoats / Seals

n There are a variety of topcoats / seals available. Silicated dips, polymers/lacquers, cross-linking polymers, lubricating seals (torque-n-tension compounds)

n Silicated dips offer some self-healing help and increase corrosion protection. These are very thin and will not cause dimensional problems with fasteners

n  Polymers / lacquers offer enhanced corrosion protection as well as scratch resistance

n  Polymers / lacquers can pose some conductivity issues

n  Polymer / lacquer films can be thick and may cause fit/dimensional issues in fasteners, especially in threaded areas

n  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.

Topcoats / Seals (cont.)

THANK YOU!

n  A big thanks to you for allowing us the opportunity to share this information with you

today. n  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@dixie-industrial.com

Terry Windham (770) 908-7909 terryw@dixie-industrial.com