Metal Finishing
101
Part 1. Metal Finishing and Electroplating
August 22, 2005
What We Will Cover Today• Introduce the Problem• 40 CFR 413 – Electroplating• 40 CFR 433 – Metal Finishing• 6 Main or “Core” Operations
– Electroplating– Electroless Plating– Anodizing– Coatings– Etching and Chemical Milling– Printed Circuit Board Manufacturing
• How to determine the Difference Between 433 and 413• Other Metal Categories
433 or 413, What’s the Problem?• Two Categorical classifications covering
the same processes.• How do we know….
– if it is a categorical discharger (433 or 413);– If so, is it 433 or 413.– Or is it some other category altogether?
40 CFR 413 - Electroplating• Original "surface finisher" regulation promulgated
in 1979 and 1981• Covers 6 main or “Core” processes
– Electroplating– Electroless Plating– Anodizing– Coatings– Etching and Chemical Milling– Printed Circuit Board Manufacturing
40 CFR 433 – Metal Finishing• Promulgated in 1984• Most 413 CIUs moved to 433• Covers same 6 main “core” processes as 413
– Electroplating– Electroless Plating– Anodizing– Coatings– Etching and Chemical Milling– Printed Circuit Board Manufacturing
• 40 other ancillary metal finishing operations– Cleaning, painting, machining, grinding, polishing, barrel
finishing, burnishing, impact deformation, pressure deformation, shearing, heat treating, thermal cutting, welding, brazing, soldering, flame spraying, sand blasting….
Basics of 433 and 413
• Both use various chemical processes to change the surface of a piece of metal, either adding a layer or taking a layer off - often referred to in the business as “surface finishing”
• Some, like plating, very easy to see the surface change.
• Some, like iron phosphating, sometimes difficult to detect with the untrained eye.
Basic? Electro-plating
Process
Identify Base Metal
Clean
Acid Descale & Activate
Pre-Plate(If required)
Final Plate
Post Treatments(As Specified)
Rinse
Rinse
Rinse
Rinse
Rinse
Dry & Package
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 2R
Step 3R
Step 4R
Step 5R
Step 6R
Basic Electroplating Procedure
For Example: Steel,Cooper , Brass
For Example:Degrease, Soak, &
Electroclean
For Example:Hydrochloric, Sulfuric,
or Fluoboric Acids.(Some cases Peroxide
Descale or Brite Dip
For Example:Cadmium, Chromium,Copper, Gold, Lead,
Nickel. Silver, Solder, &Tin
For Example:Chromates, Lacquers,
& Seals
For Example: Box orHot Air Spin Dryers
For Example: Copper,Sulfamate Nickel, or
NickelIf more than one is
specified Repeat Steps4 & 4R as needed.
The Big 6
Core #1 - Electroplating• Electroplating is the deposition of a metallic coating
onto the surface of an object by putting a negative charge onto the object and immersing it into a solution which contains a salt of the metal to be deposited.
Core #1 - ElectroplatingBefore - dull
After - shiny
Core #2 - Electroless Plating• Electroless plating is “plating without the use of
electrical energy”- a chemical reduction process which depends upon the catalytic reduction process of metal ions in an aqueous solution (containing a chemical reducing agent) and the subsequent deposition of the metal.
• Typical choice for irregularly shaped, highly detailed part shapes because of completely uniform deposit thickness and high precision.
Core #3 - Anodizing• Anodizing is the electrochemical process by which
the surface of a metal part is converted into a metal oxide
• Aluminum is the most common metal anodized
1- Aluminum base metal
3- Aluminum oxide layer (Core #3)
5- Coloring matter
Anodizing
Core #3 - Anodizing
•A cathode is connected to the negative terminal of a voltage source and placed in the the anodizing solution typically made up of sulfuric acid. A metal part is connected to the positive terminal ofthe voltage source and also placed in the anodizing solution. When the circuit is turned on, the oxygen from the water molecules in the anodizing solution will be liberated and combine with the metal molecules? ions? on the surface of the part, forming a metal oxide coating.
Core #4 - Coating
• Any operation that includes:–Chromating, –Phosphating, –Metal coloring, and –Passivating
Core #4a – Chromating• Portion of the base metal is converted to a
component of a protective film.
1- Aluminum base metal
2- Chromate coating-core #4
4- Lacquer coating
•Film is composed of:–Base metal–Hexavalent chrome–Active inorganic or organic compounds
Core #4a – Chromating
Before Chromating (shiny)
After Chromating (dull)
Core #4b - Phosphating• Immersion of steel, iron, or zinc plated steel in
phosphoric acid to add a coating to the surface so that paint or some other substance will stick to the metal
• Zinc phosphating – new layer is easy to see, shiny, but not as shiny as electroplating
• Iron phosphating – new layer is more difficult to see. Iron phosphated surface looks like it has a grayish scaly layer on it – look closely!– Some, especially line workers, will call iron
phosphating “cleaning” – “just cleaning up the part prior to painting!”
Core #4b - Phosphating
Iron Phosphating
Core #4c - Metal Coloring
• Chemical method of converting the metal surface into an oxide or similar metallic compound to produce a decorative film.
Core #4d - Passivating
• Process of forming a protective film on metals by immersion on an acid solution– Nitric acid– Nitric acid with sodium dichromate
Core #5 - Etching and Chemical Milling
Core #5 - Etching and Chemical Milling
• Etching is the controlled removal of metal by dissolving it with chemical reagents or etchants to produce a specific design configuration.
• Chemical milling is the same process except the rates and depths of metal removal are much greater in chemical milling.
Core #6 - Printed Circuit Board Manufacturing
Core #6 - Printed Circuit Board Manufacturing
• Formation of circuit pattern of conductive metal (usually copper) on nonconductive board materials such as plastic or glass. Employs “cores” # 1, 2, and 5 in sequence.
• Five basic Steps– Cleaning + surface preparation– Catalyst + electroless plating (#2)– Pattern printing + masking– Electroplating (copper) (#1)– Etching (#5)
What about all the
rinsing and cleaning?
Identify Base Metal
Clean
Acid Descale & Activate
Pre-Plate(If required)
Final Plate
Post Treatments(As Specified)
Rinse
Rinse
Rinse
Rinse
Rinse
Dry & Package
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 2R
Step 3R
Step 4R
Step 5R
Step 6R
Basic Electroplating Procedure
For Example: Steel,Cooper , Brass
For Example:Degrease, Soak, &
Electroclean
For Example:Hydrochloric, Sulfuric,
or Fluoboric Acids.(Some cases Peroxide
Descale or Brite Dip
For Example:Cadmium, Chromium,Copper, Gold, Lead,
Nickel. Silver, Solder, &Tin
For Example:Chromates, Lacquers,
& Seals
For Example: Box orHot Air Spin Dryers
For Example: Copper,Sulfamate Nickel, or
NickelIf more than one is
specified Repeat Steps4 & 4R as needed.
Cleaning – Ancillary #7• Only action is to remove dirt, oil, etc. from the
top of the surface of the metal. • Does not change the character of the actual
metal surface or the color of the metal itself• Will only look different because dirt layer is
gone• Often confused with phoshating (#4b)
– Usually a 5 stage process: alkaline cleaning, rinse, phosphate, rinse, and sealer or chromating or something
Rinsing• Generally rinsing is required after each (core or
ancillary) process step.• Removes chemicals from the previous process step
that are lingering on the surface of the part, thus preventing cross-contamination of process tanks.
• Rinse tanks are generally discharged continuously or in batches to the WWTF.
• Rinse water is considered part of the operation for the purposes of deciding whether an IU discharges from an operation
Multi-Stage CountercurrentFlow Rinse
Drain
Work Flow
Water Flow
Two Stage Rinse Tank –Hand Dunking
Two Stage Rinse –Power Assisted Dunking
How do we know which is which?
• Information needed – both in the terms the IU uses, and in regular words you understand– what they make– raw materials and how they are used in the manufacturing
process– other materials used in manufacturing– how they make it - process flow chart (physical and
chemical processes), which steps generate wastewater, and can you see a difference in the surface between any process steps?
More
Information needed (continued)
– What operations do they use to change the shape of metal pieces (see Determining Metals CIUs-Part 2)
– Applicable SIC codes– Operation start-up date– Last time production changed (new tanks, base
metals, plating materials)
How do we know which is which?• 433 – applies to SIUS who PERFORM one of the 6
“core” processes – AND discharge from any of the 6 “core” OR 40
“ancillary” – All process effluent is 433
• 413 - only applies to SIUs who began operation before September 1982 AND ARE EITHER– A Job Shop – Own <50% metal (annual area basis)
worked on OR – An Independent Circuit Board Manufacturer – make
circuit boards principally for sale to other companies
How do we know which is which?Are any of the main “core” 6 performed? Not 433 or 413No
Began operation before 9/1/82 + no significant production changes since
Yes
Yes 433.17 (new source)
YesIndependent Circuit Board ManufacturerNo 413
No 433.16 (existing source)
Yes Discharge from any of the 46? No Not 433 or 413
Own <50 % (area) of materials processed
No
Yes 413
How do we know which is which?
• see 40 CFR 433.10(c)(2) and 433.1(c) and (d) and 40 CFR 413.01(a)
• 433/413 Verification Form available from DWQ - SIU fills out to determine which one applies
• Guidance Manual for Electroplating and Metal Finishing Pretreatment Standards, EPA, February 1984. EPA-440/1-84/091g
• Ask your friendly PERCS Staff
How do we know which is which?
• Development Document for Effluent Limitations Guidelines and Standards for the ….– Metal Finishing Point Source Category, EPA,
June 1993. EPA-440/1-82/091– Electroplaters Point Source Category, EPA,
August 1979. EPA 440/1-79/003• Ask your friendly PERCS Staff
How do we know which is which?
• Comp Guide, Appendix 3-D– categories, subparts, pretreatment regulated
parameters, new source dates• Comp Guide, Appendix 3-F
– EPA contacts for categories• Ask your friendly PERCS Staff
Distinguishing Metal CIUs – Part 2
• Not everyone who performs 6 “Core” is 433 or 413. • 40 CFR 465 - Coil Coating
– Coil coaters perform one of 6 “basic” on metal piece that starts and ends with coil, uncoiled to do surface finishing
– 465 also includes can making - do coating• 40 CFR 466 - Porcelain Enameling
– perform one of 6 “basic” on porcelain• What about the SIU who "forms" the basic shape of
the part before they plate it?
433/413 Metal Shape Changing
• 413/433s –change shape of metal piece in “relatively minor way” –– drilling and/or threading holes– making bends, holes, dents, etc. by
• impact deformation – Dana says “ka-boom!”• pressure deformation – slow, steady force
– Grinding, machining, or cutting off areas
433/413 Metal Shape Changingdrilling threads
Pressure/impact Deformation? welding
Punching holes
Other Metals Categories - Major Shape Changing
• Casting = melt metal, pour into cast, allow metal to solidify in new shape
• Rolling = reduce diameter by passing metal between lubricated rollers (metal hot or cold)
• Drawing = pulling metal thru a die to make diameter thinner or change shape
• Extruding = use pressure to force metal to flow thru die
• Forging = use pressure to change shape, with or without dies. Usually on heated metal.
Other Metals Categories - Major Shape Changing
• Extrusion and drawing turned plug of aluminum into the fire extinguisher can – 40 CFR 467 – Aluminum Forming.– Note hole from pressure
testing (433/413 ancillary #45)• LP gas regulator – casting
(464)• Tungsten carbide drill bit –
powder forming (471)
Other Metals Categories - Major Shape Changing
• Where does 413/433 pressure deformation end and “other metals categories” forging begin?
• Cladding (471) versus brazing (433/413)• for some Other Metals Categories, when perform
casting, drawing, etc., and then do “surface finishing” (6 basic/40 ancillary), the surface finishing wastes are not covered by 413 or 433, but are covered by the casting, drawing, etc., regulation– 40 CFR 433.10(b) and 40 CFR 413.(b)
Other Metals Categories• 420-Iron and Steel• 421-Nonferrous metals manufacturing• 424-Ferroalloy Manufacturing• 461-Battery• 464-Metal Molding and Casting• 465-Coil coating• 467-Aluminum Forming• 468-Copper Forming• 471-Nonferrous Metals Forming and
Metal Powders
DWQ Pretreatment Contacts• Jeff Poupart, Supervisor – ext. 527• Dana Folley, A - F Towns- ext. 523 • Jon Risgaard, G - M Towns- ext. 580• Deborah Gore, N - X Towns- ext. 593• Daryl Merritt, Y-Z Towns- ext. 554
Phone #: 919-733-5083 email: [email protected]
DWQ Pretreatment Website
Homepage:http://h2o.enr.state.nc.us/Pretreat/index.html
Categorical items on Permit Writing Page
Thanks to…
• Burrell Brock, City of Raleigh• Chris Hord, Surtronics,Inc• Dana Folley, PERCS Unit
Thank You!
Now What?
• Inspecting a Metal Finishing/Plating Facility– by Dawn Padgett