Welcome to E-mold rapid manufacturing Ltd !
linkedin twitter youtube
Tel : (+86)1345 0999 345 Email: louisa@e-moldrapid.com
Blog
Home > Blog > Anodizing Reference Guide
Anodizing Reference Guide
Jul 05,2019 | Views: 115

Anodizing is used to increase surface hardness, wear resistance and dielectric strength.

Anodizing can also provide a good base for painting or colouring, creating an extremely stable but porous oxide layer on the surface of aluminum.

 

 

Type                                                                Thickness

Type II

Conventional coatings produced                                    1.8μ-25.4μ
from sulfuric acid bath

Type I A                                                                             

Conventional coatings produced                                    0.5μ-7.6μ (microns)
from chromic acid bath

Type I B

Low voltage chromic acid anodizing (20 volts)               0.5μ-7.6μ
Used for 7000 series alloys

Type III

Hard coat (uniform anodic coatings)                              12.7μ-115μ
Class 1
- Non dyed
• Class 2
- Dyed

 

Test Methods For Type II Anodized Aluminum
 

Oxide Coating Thickness
ASTM B 244-79
ASTM B 487-85                         Min Thickness
Class I                                      18 Microns (μ)
Class II                                     10 Microns

Oxide Coating Weight and Apparent Density
ASTM B 137-89                         Min Weight                         Min Density
Class I                                     4.18 mg/cm2                       2.32 g/cm3
Class II                                    2.40 mg/cm2                       2.32 g/cm3
(Adopted from AMAA 611)

Corrosion Resistance

ASTM B 117-90                         Min Hours                         Max Spots
Class I 3000 15
Class II 1000 15

Seal Quality

ASTM B 136-77
ASTM B 680-80
ISO 3210                                   Max Weight Loss
Class I                                        40 mg/dm2
Class II                                       40 mg/dm2

 

Aluminum Alloy Reference for Anodizing
 

Series
(AA)*
Alloying
Constituants
Metal
Properties
Coating
Properties
Uses A.Q.**
Types
Non-A.Q.**
Types
1000 None soft, conductive clear, bright cans
architectural
none 1100, 1175

 

 

 

 

 

 

Finishing advice: Care should be taken when racking this soft material;
good for bright coatings; susceptible to etch staining.
2000   Copper         

very strong,hard, 
low elongation 

yellow, poor
protection
aircraft
mechanical
none 2011, 2017
2219, 2224

 

 

 

Finishing advice: Since copper content is > 2%, these produce yellow,
poor weather-resistant coatings; don't mix with other alloys on load
3000   Manganese     strong, small    
grains

grayish         

brown

cans,
architectural
lighting
none 3003, 3004

 

 

 

 

Finishing advice: Difficult to match sheet-to-sheet (varying degrees of gray/brown);
used extensively for lighting
4000   Silicon           strong, fluid     

dark gray      

architectural,
welding, wire
none 4043, 4343

 

 

 

Finishing advice: Produce heavy black smut which is hard to remove;
4043 & 4543 used for architectural dark gray finishes in past years
5000   Magnesium    strong, ductile,
fluid     

clear, good
protection     

architectural,
welding, wire,
lighting
5005,
5657
5052, 5252

 

 

 

 

Finishing advice: For 5005 – keep silicon < 0.1% and magnesium between 0.7%
and 0.9%; watch for oxide streaks; 5005 used extensively for architectural
6000  

Magnesium

&Silicon         

strong, ductile    

clear, good
protection    

clear, good
protection
6063,
6463
6061, 6101

 

 

 

Finishing advice: Matte-iron > 0.2%; bright-iron < 0.1%;
6063 best match for 5005; 6463 best for chemical brightening
7000  

Zinc                 

very strong          

clear, good
protection      

automotive  none 7029, 7046,
7075

 

 

   

Finishing advice: Zinc over 5% will produce brown tinted coating;
watch zinc in effluent stream; good for bright coatings

* AA - Aluminum Association
** A.Q. - Anodizing Quality - material suitable for architectural anodizing applications

 

TYPE I “Chromic Acid”
Color will vary from clear to dark gray depending on alloy. Copper bearing alloys only
yield gray colors. Not as readily dyed as sulfuric anodize due to thinness of coating.
New salt spray requirement is 336 hours
(5% solution per method 811 or FED-STD-No. 151)

 

Type I                  Chromic acid anodized coating. This process is used principally for
                                the treatment of aircraft parts. An example is the Bengough-Stewart
                                process where a 30-50 g/l chromic acid bath is maintained at
                                100°F and the voltage is gradually raised to 50V. Adjustments
                                are made for high copper, zinc, and silicon alloys. Coating weights
                                must be greater than 200 mg/ft2. Criteria for corrosion resistance,
                                paint adhesion, and paint adhesion testing must be specified.

 

Type IB                Low voltage (22)2V) chromic acid anodized coating. Typically associated
                                with higher temperature, more concentrated chromic acid electrolytes.
                                Coating weights must be greater than 200 mg/ft2. Criteria for corrosion
                                resistance, paint adhesion, and paint adhesion testing must be specified.

 

Type IC                Anodized coating produced in a non-chromic acid electrolyte.
                                As with other Type I coating processes, the treatment is designed to
                                impart corrosion resistance, paint adhesion, and/or fatigue resistance
                                to an aluminum part. Coating weights must fall between 200-700 mg/ft2.
                                Criteria for corrosion resistance, paint adhesion, and paint adhesion
                                testing must be specified.

 

TYPE II “Sulfuric Acid”

MECHANICAL FINISHING A.A. COMMON DESCRIPTION EXAMPLES OR FINISHING METHODS
As fabricated M-10   Unspecified  
  M-12   Nonspecular as fabricated No particular reflectiveness
Buffed M-21   Smooth specular Polished first with coarser than 320 grit, followed by 320 grit, then buffed with Alum oxide
  M-22   Specular Buffed with Alum oxide compound
Directional textured M-31   Fine satin Sanded with 320-400 grit Alum oxide
  M-32   Medium satin Sanded with 180-220 grit Alum oxide
  M-33   Coarse satin Sanded with 80-100 grit Alum oxide
  M-35   Brushed Brushed with stainless steel wire brush
CHEMICALFINISHING        
Nonetched Cleaning C-11   Degreased Organic solvent treated
  C-12   Inhibited chemical cleaned Soap cleaner only
Etched C-22 R-1 Medium matte Sodium hydroxide
(caustic soda) 30-45 gr/li
@ 60-65˚C for 5 min
Brightened C-31 R-5 Highly specular Chemical bright dip solution of
the proprietary phosphoric-nitric
acid type, or electropolishing
  C-32   Diffuse bright Etched finish C-22 followed
by Brightened finish C-31
ANODIC COATING        
General A-11   Prep for other
applied coatings
15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 10 min.
sometimes not sealed
Decorative A-21   Clear coating 2.5μ-7.5μ 15% Sulfuric acid @ 20˚C,
12 amps/sq ft.
  A-211 200 Clear coating min. 2.5μ 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 10 min.
  A-212 201 Clear coating min. 5μ 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 15 min.
  A-213 202 Clear coating min.7.5μ mil 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 20 min.
  A-23   Coating with
impregnated color
15% Sulfuric acid @ 20˚C,
12 amps/sq ft., followed by dyeing
with organic or inorganic colors
  A-24   Coating electrolytically 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. , deposited
color followed by deposition
of inorganic metallic salts
Architectural
Class 2
A-31 204 Clear coating 15% Sulfuric acid @ 20˚C,
12 amps/sq ft.
10μ-18μ A-33   Coating with
impregnated color
15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 30 min.,
followed by dyeing with
organic or inorganic colors.
  A-34   Coating electrolytically 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. deposited color for
30 min., followed by deposition
of inorganic metallic salts.
Architectural
Class 1
A-41 215 Clear coating 15% Sulfuric acid @ 20˚C,
12 amps/sq ft.
18μ and more A-43   Coating with
impregnated color
15% Sulfuric acid @ 20˚C,
12 amps/sq ft. for 60 min.,
followed by dyeing with
organic or inorganic colors.
  A-44   Coating electrolytically 15% Sulfuric acid @ 20˚C,
12 amps/sq ft. deposited color for
60 min., followed by deposition
of inorganic metallic salts.

Data derived from “Designation System for Aluminum Finishes” (DAF45), published by The Aluminum Association

 

TYPE III “Hard Coating”
Color will vary from light tan to black depending on alloy and thickness. Color overtones
listed below may vary with the use of additives and/or the process. Can be dyed in darker
colors depending on thickness. Coating PENETRATES base metal as much as builds up
on the surface. The term THICKNESS includes both the buildup and penetration. Provides
very hard ceramic type coating. Abrasion resistance will vary with alloy and thickness of
coating. Good dielectric properties. Corrosion resistance is good, but recommend sealing in
5% dichromate solution where increased corrosion resistance is required. Where extreme
abrasion resistance is required do not seal as some softening is encountered.

 

Type III Anodize Thickness Guide

Alloy Major Constituent (in) Maximum Thickness* Color Overtones***
5005 Magnesium .0035 Gray/Brown
5052 Magnesium .0035 Gray/Brown
5083 Magnesium .0035 Gray/Brown
6061 Mag/Silicon .003 Dark Gray
6063 Mag/Silicon .004 Green
6105 Mag/Silicon .0035 Gray/Green
6262 Mag/Silicon .0025 Gray
6463 Mag/Silicon .003 Gray
7075 Zinc .004 Bronze



Prev: General Tolerances to DIN ISO 2768 Next: Parting Line Selection
Search

Contact us

E-mold rapid manufacturing Ltd !
Louisa Xiao

Email : louisa@e-moldrapid.com

Tel : (+86)1345 0999 345

twitter linkedin youtube