Shim Finishes

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SPIROL controls quality, lead time and cost by performing most secondary finishing processes in-house. These processes include heat treating, grinding and lapping, high speed polishing, deburring, finishing, edge-bonding, passivating, bar coding, and a variety of part marking and packaging techniques. As a testament to our commitment to quality and our leadership position in the industry, SPIROL is Nadcap accredited to passivate Shims in-house per AC7108 Rev J, AC7108/4 Rev C, AC7108/12 Rev A. In addition, we have partnerships with ANAB accredited ISO/AS9100-certified companies to supplement our internal secondary processing and to support unique requirements. This enables us to provide the surface finishes listed below:

Alodine®

The Alodine® process is a chemical dipping process that administers a chromate coating on aluminum or aluminum alloy parts. Common Alodine® specifications that SPIROL has supplied are:1008 Temper #4.

  • MIL-C-5541
  • MIL-DTL-5541
  • MIL PRF-5541

Common examples of why a company would use an Alodine® Shim are:

  • For corrosion protection
  • To provide an adherent base for paint
  • For decorative purposes to provide a colored, bright surface.

Alodine Shims are available in different colors ranging from clear to iridescent gold and darker brown tints.

 

Anodized

Anodizing is a process where an oxide film is applied electrolytically to aluminum using an acid base. Common anodize specifications that SPIROL has supplied are:

  • AMS 2482
  • AMS 2468
  • AMS 2469
  • MIL-A-8625 type I
  • MIL-A-8625 type II, III
  • MIL-PRF-8625

Companies would use an anodized Shim for several reasons including to increase corrosion resistance, to increase paint adhesion, to allow subsequent plating, and to provide excellent wear and abrasion properties to the Shim. Anodizing is also done to provide a decorative finish for the Shim.

 

Black Oxide

Black oxide coating is a chemical dip process used primarily to color the part black. SPIROL has supplied Shims that have been black oxidized per the following specifications:

  • MIL-DTL-13924
  • MIL-C-13924
  • AMS 2485
  • ASTM D769
  • ISO 11408

Industries that often require black oxide Shims include: automotive, aerospace, military and defense, electronics, hand and power tools, and industrial. Black oxide is applied to enhance the appearance and functionality of metal parts and offer a durable, black finish that improves corrosion resistance, lubricity, and aesthetic appeal. Black oxide is also used to reduce light reflection of the metal Shim.

 

Cadmium Plated

Cadmium plating is a process that electrolytically deposits a bright, silvery-white, bluish-gray, or yellow-ish plating. Common cadmium plating specifications that SPIROL has supplied are:

  • AMS 2400
  • AMS-QQ-P-416
  • FED-QQ-P-416
  • QQ-P-416

Common industries that require cadmium plated Shims are aerospace, marine, transportation, electronics and consumer products because of the excellent protection to steel against corrosion, particularly in a salt atmosphere.

While cadmium plating was very popular a few decades ago, most new products or new revisions of existing products are protected by a different plating or coating due to its environmental and hazardous concerns. Therefore, you most often see cadmium plating on legacy items.

 

Chem Film

Chem film is a chemical dipping process to administer a chromate coating on aluminum or aluminum alloy parts. Alodine® and Iridite® are trade names of this process. Common finish specifications for chem film used on Shims are:

  • MIL-C-5541
  • MIL-DTL-5541
  • MIL PRF-5541

Industries that often require chem film Shims are aerospace, military and defense, electronics, maritime, and medical equipment. 

Examples of why a company would use a chem film Shim are:

  • For corrosion protection
  • To provide an adherent paint base
  • For decorative purposes to provide a colored, bright surface.

Chrome Plating

Chrome plating is an electroplating process that applies a thin layer of chromium to a metal Shim. Common chrome plating specifications for Shims are:

  • AMS 2406
  • ASTM B650
  • ASTM B456
  • QQ-C-320
  • MIL-C-20218
  • MIL-DTL-23422
  • SAE-AMS-QQ-C-320

One example of this plating option is hard chromium plating per AMS 2406 specified for Shims used in aerospace applications where there are established rigid requirements for abrasion resistance and reduced friction to extend the life of the Shim in extreme wear conditions.

 

Copper Plating

Copper plating is an electrochemical process where a thin layer of copper is deposited onto a metal surface using an electric current. SPIROL has supplied Shims with copper plating per the following specifications:

  • MIL-C-14550
  • ASTM B734
  • AMS 2418,

Industries that often require copper plated Shims are electronics, telecommunications, automotive, and aerospace. Copper plating provides corrosion resistance, enhanced conductivity, and improved adhesion for subsequent coatings.

 

Iridite®

Iridite® is a chemical dipping process that administers a chromate coating on aluminum or aluminum alloy parts. Common Iridate® specifications that SPIROL has supplied are:

  • MIL-C-5541
  • MIL-DTL-5541
  • MIL PRF-5541

Common examples of why a company would use an Iridite® Shim are for corrosion protection, providing an adherent paint base, or for decorative purposes to provide a colored, bright surface.

 

Mechanical Zinc (Mechanical Galvanized)

Mechanical zinc is a process that deposits a zinc coating on metal Shims using a tumbling action with glass beads and metal powder. The most common mechanical zinc specification for Shims is ASTM B695.

Mechanical zinc Shims are commonly used in the aerospace and automotive industries as it offers corrosion resistance and a uniform finish. 

 

Electroless Nickel Plate

Electroless nickel plate is a process that uses a chemical bath to deposit a nickel / phosphorous layer onto the metallic surface of the Shim. Common electroless nickel plating specifications for Shims are:

  • AMS 2404
  • ASTM B733
  • Mil-C-26074E

Electroless nickel plated Shims are used in a variety of industries including aerospace, automotive, manufacturing, electronics and medical due to its corrosion protection and wear resistance.

 

Passivation

Passivation is a chemical process that enhances the corrosion resistance of metals and alloys, particularly stainless steel, by removing surface contaminants and restoring a protective chromium oxide layer. Common passivation specifications for Shims include:

  • AMS2700
  • ASTM A967
  • QQ-P-35

Industries that often require passivation include aerospace, medical, food processing, electronics and automotive, ensuring the longevity and safety of critical components.

 SPIROL is Nadcap accredited to passivate Shims in-house per AC7108 Rev J, AC7108/4 Rev C, AC7108/12 Rev A.

 

Prime and Paint

Prime and paint is a process where priming is done to create a base or binder for subsequent painting. Common prime and paint specifications for Shims are:

  • MIL-PRF-23377
  • MIL-DTL-53022
  • MIL-DTL-46168
  • MIL-PRF-22750

Priming and painting of Shims is done primarily to provide additional corrosion resistance or simply for identification or decorative purposes. Two industries that require Shims that have been primed and painted are aerospace and military.

  

Silver Plate

Silver plating is a process in which base metals are coated with a layer of silver. SPIROL has supplied silver plated Shims per the following specifications:

  • AMS 2410
  • AMS 2412
  • ASTM B700
  • FED-QQ-S-365
  • MIL-QQ-S-365

Silver plating prevents parts from seizing or galling, especially in high-temperature or high-stress environments. Common industries that require silver plated Shims are aerospace and automotive. 

 

Zinc Phosphate

Zinc phosphate is a common coating added to metal Shims through either immersion or spraying a diluted solution of phosphoric acid and soluble zinc to the metal surface which causes a reaction that forms a bonded zinc phosphate coating. Common zinc phosphate specifications for Shims include:

  • AMS 2480
  • ASTM F1137
  • MIL-DTL-16232
  • TT-C-490
  • WSD-M3P35

Companies commonly use a zinc phosphate Shim because the coating acts as a barrier against environmental factors such as moisture and salt, which would otherwise accelerate corrosion. Metal Shims treated with zinc phosphate exhibit enhanced wear resistance making them suitable for heavy-duty applications.

 

Zinc Plating

Zinc plating is a surface finishing process where a thin layer of zinc is electrochemically deposited onto a metal surface. The most common zinc plating specification for Shims is ASTM B633.

Companies use zinc plated Shims to create a protective barrier against moisture and oxygen, preventing rust and extending the lifespan of the metal parts. If parts are heat treated to a hardness greater than RC38, they must be baked to effuse trapped hydrogen to help prevent hydrogen embrittlement.

 

 

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