Metal Anodizing Services in Houston, Texas

Metal Anodizing

  • MIL-A-8625 Type II, Class 1 Clear
  • MIL-A-8625 Type II, Class 2 (Specify Color)
  • MIL-A-8625 Type III, Class 1 Hard
  • MIL-A-8625 Type II, III, Class 1 or 2 Hard W/O or W/Color
  • AMS 2471 & AMS 2472

Anodizing (conventional Type II sulfuric anodizing) improves the performance of your parts for:

  • Wear Resistance
  • Lubricity
  • Dielectric Properties
  • Heat Dissipation
  • Corrosion Resistance
  • Bonding
  • Aesthetics, ideal for producing intense colors

Houston Metal Anodizing

During sulfuric anodizing, no metallics are involved other than aluminum. Unlike electro-deposited metallic plating, where plating builds up by depositing on a base metal, an anodic coating penetrates and grows on the base metal by converting aluminum to aluminum oxide. The ratio of growth/penetration for anodic coatings is typically 50/50*.

Proper formation of aluminum oxide coatings provides aluminum with a natural decorative appearance and increased resistance to corrosion and abrasion. Normally between .0001" to .001"; thick, sulfuric anodizing lends itself readily to clear and color work, as the coating is more transparent than other types of anodizing. In addition, it serves as a base for color absorption to create decorative finishes. Dyes can be deposited into the pores of the anodized layer and then sealed. The result is a highly desirable, rich, intense, permanent color finish.

Aluminum can be anodized and dyed to match a given decor or to assimilate a particular metal.

The Anodizing Process

Anodizing entails the immersion of an aluminum part in an electrolyte where an electric current is passed through the part. The surface is converted to aluminum oxide — one of the hardest substances known.

Proper formation of aluminum oxide coatings provides aluminum with a natural decorative appearance and increased resistance to corrosion and abrasion. In addition, it serves as a base for color absorption to create decorative finishes.

Sealing

The final treatment of clear or dyed anodized aluminum is sealing to close the pores of the aluminum oxide and render the coating non-absorptive. Sealing is accomplished by immersion in deionized water containing either nickel acetate, nickel fluoride, sodium dichromate or near boiling ionized water (water chemically distilled to a high degree of purity).

Sealing hard coat yields:

  • Increased Corrosion Resistance
  • Better Lubricity
  • Better Light Fastness
  • Better Weather Fastness

Alloys And Castings: The Effects on Anodizing Processes

Each alloy anodizes differently because alloy metals change the conductivity of the part and cause it to form aluminum oxide, either faster or slower. All aluminum can be anodized, but some alloys work better than others. Castings tend to give the anodizer the most problems because of the porosity in the castings and alloying materials used.

Properties

Sulfuric anodizing has superb dielectric strength, good abrasion resistance, and excellent corrosion resistance. Type II anodizing is mostly used for decorative anodizing as it lends itself to the dying of light and dark colors, depending on the coating thickness. Where a colorless film is important, as for ornamental purposes or reflectors, Type II anodizing is used. There are some disadvantages to consider when contemplating the sulfuric acid process. The following types of parts should be avoided due to the corrosion nature of sulfuric acid: assembled parts, parts containing welds, joints, and recesses in which the anodizing solution may be retained.

Dye Anodizing

Proper formation of aluminum oxide coatings provides aluminum with a natural decorative appearance and increased resistance to corrosion and abrasion. Normally between .0001" to .001" thick, sulfuric anodizing lends itself readily to clear and color work, as the coating is more transparent than other types of anodizing. In addition, it serves as a base for color absorption to create decorative finishes. Dyes can be deposited into the pores of the anodized layer and then sealed. The result is a highly desirable, rich, intense, permanent color finish.

Aluminum can be anodized and dyed to match a given decor or to assimilate a particular metal.

Hard Anodizing (Type III Anodizing - also referred to as Hardcoat Anodizing)

  • MIL-A-8625 Type III, Class 1 & 2

Hardcoat anodizing exceeds wear characteristics of other hard coatings such as electroless nickel, hardchrome, and ceramic.

The hardcoat anodizing process produces superior hardness and denseness — when a part is hardcoated, it increases the micro finish 2-5 times, depending on the alloy.

  • Unmatched wear properties
  • Coatings wear as well as or better than hardened steels (HRC values of 70) as judged by Suga and Taber Wear tests.
  • Can achieve salt spray resistance in excess of 1000 hours.
  • Good for salvage work of parts with critical dimensional specifications.
  • Can achieve very tight tolerances.
  • High dielectric strength to 2000VDC.
  • Heat dissipation

Taber abrasion testing shows that hardcoat exceeds wear characteristics of other hard coatings such as electroless nickel, hardchrome, and ceramic.

Some industrial applications of hardcoat anodizing include highly intricate parts such as pistons, anti-lock brake assemblies, pump components, valves, sliding parts, insulation plates and transmission parts. Some retail applications for hardcoat anodizing and Sulfuric anodizing include cookware, bike rims, locks and levels.

Salvage Through Hardcoating

The use of hardcoat for salvage operations has proven very successful. Parts rejected because of bores that have been machined oversized are being hardcoated and honed to become acceptable parts. Wrought and cast alloys both lend themselves to salvage operations, but the hardcoat thickness that can be applied is governed by the alloy of the salvage part. Salvage through hardcoat pays off. A prime example is in the aircraft industry, where parts costing thousands of dollars to machine are being salvaged by hardcoating the oversized bores.

The final appearance of a hardcoated surface depends on the alloy and thickness of the coating. The color of an undyed finish can range from gray to black and various shades of bronze can be produced. If close tolerances aren't a factor, Bright Dip will improve the appearance of the finish.

Alloys and Castings: The Effects on Hardcoat Anodizing Processes

The final appearance of a hardcoated surface depends on the alloy and thickness of the coating. The color of an undyed finish can range from gray to black and various shades of bronze can be produced. If close tolerances aren't a factor, Bright Dip will improve the appearance of the finish.

Over 200 aluminum alloys, each with up to eight different tempers or hardness values, are available. Each alloy and temper displays unique characteristics with respect to anodic films that can be formed.

Metal Finishing Services

Surface Techniques, Inc.
1545 Blalock Road
Houston, Texas 77080

Phone: (713) 932 - 8050
Fax: (713) 932 - 1932

Hours:
Monday-Friday 8:00am-2:30pm