AMS2438 is a comprehensive standard outlining stringent requirements, control factors, and meticulous testing procedures for thin dense chrome plating. This standard ensures uniformity, durability, and quality of the plating components in industrial applications. The AMS2438 standard, while formulated under the SAE (Society of Automotive Engineers) Aerospace Material Specifications, is not exclusively limited to aerospace applications. Although it substantially influences aerospace industries, providing precise guidelines for chrome plating in aircraft components, it is equally applicable to other sectors, such as automotive, where high-performance and stringent quality control are imperative.

Control Factors:

Detailed specifications under this section ensure a comprehensive approach to quality control, including considerations for surface preparation, plating bath composition, and precise methods for determining plating thickness.

Processing & Testing Reports:

Processors must submit reports confirming adherence to specifications, successful execution of all required tests, and providing detailed information such as the lot number, part number, and quantity.

Multiple Testing Procedures:

AMS2438 mandates a variety of preproduction, acceptance, and periodic tests to ensure compliance with not only AMS2438 but its sub-specifications referenced. These tests are crucial for determining the endurance, uniformity, and reliability of the plated components.

• • Taber Abrasion Test: A precise procedure assesses wear characteristics, involving specific conditions, handling, measurement protocols, machine setup, execution, and calculation of the Taber Wear Index.
  • Adhesion Test: This is crucial for ensuring the plated layer’s bond strength to the substrate, with clear stipulations for procedural adherence and assessment.
  • Salt Fog Corrosion or Porosity Tests: Essential for determining the plated components’ ability to withstand corrosive environments, ensuring longevity and reliability.
  • Hydrogen Embrittlement Test: This is vital to ascertain the vulnerability of plated components to premature failure due to hydrogen incorporation during the plating process.

Resampling & Retesting Protocols:

In case of failure in any of the acceptance tests, the standard provides detailed guidelines for stripping, retreating, replating, and retesting of parts, ensuring compliance with quality and specifications.

Acceptance & Rejection Criteria:

Criteria for the acceptance or rejection of plated parts are outlined based on their adherence to specified requirements and approved modifications. Any deviations necessitate corrective actions and adherence to the defined protocol.

Dimensional Considerations & Plating Integrity:

The document specifies the implications of the plating process on product dimensions and emphasizes the importance of clear communication between the part fabricator and the plating processor to maintain dimensional integrity.

Delivery, Packaging & Documentation:

Ensuring the preservation of physical characteristics and properties during handling, packaging, and transportation is imperative, with explicit guidelines for compliance with applicable regulations and documentation including acknowledgment of AMS2438F in all quotations and purchase orders.

Conclusion

The AMS2438 standard acts as an extensive guide for thin dense chrome plating, emphasizing a plethora of testing procedures and control factors to assure the production of consistent, durable, and quality plated components. The standard encompasses a range of tests, strict acceptance and rejection criteria, detailed reporting, and stipulates guidelines for packaging and delivery, making it a comprehensive framework for maintaining the highest standards in thin dense chrome plating in industrial applications.

AMS2406, designed by SAE Aerospace Material Specifications (AMS), outlines the specifications for electrodeposited hard chromium plating. It has a broad range of applications, aimed at improving abrasion resistance, enhancing tool and die life, maintaining gauge accuracy, and reconditioning worn or undersized parts, though its use is not strictly limited to these functions. The current revision in effect is Rev. P (AMS2406P).

Requirements: This standard establishes rigid requirements for hard chromium plating, ensuring functional resilience and reliability of components, making it pivotal for industries such as aerospace.

Specifications & Details

Thickness & Hardness: It specifies the requisite thickness and hardness of the chromium deposits to meet stringent performance and durability standards.

Adhesion & Quality: It mandates adherence to exacting quality controls for coating adhesion and uniformity to ensure the deposition of smooth and cohesive layers that securely bond to the substrate.

Measurement Standards: It delineates the methodologies and acceptable limits for deposit thickness measurements, promising uniform and reliable applications across diverse components.

Special Provisions: It delineates the methodologies and acceptable limits for deposit thickness measurements, promising uniform and reliable applications across diverse components.

Various Test Requirements

AMS 2406 mandates the following tests to ascertain the adherence to the specified standards:
Thickness Test: To verify that the deposit thickness complies with the specified requirements.

Adhesion Test: To ensure the coating adheres securely to the substrate.

Hardness Test: To ascertain the hardness of the deposited chromium complies with the standard requirements.

Visual Inspection: To assess the uniformity and quality of the deposit.

Hydrogen Embrittlement Test: To ensure that the plating process does not introduce hydrogen that could make the part brittle and susceptible to premature failure.

Applications & Utility

This hard chromium plating standard is vital where high wear resistance, low friction, and anti-galling properties are required. It is commonly applied in aircraft landing gears, cylinder walls, and camshafts, securing their long-term performance and reliability.

Conclusion

AMS2406 acts as a thorough standard for electrodeposited hard chromium plate, focusing on the quality, durability, and adherence of the plating. It doesn’t distinguish between different classes or appearances but concentrates on functional attributes, acting as a crucial reference for industries aiming at high-quality and high-performance components. Its precision and adaptability make it a standard of choice across various industrial applications, ensuring components meet strict quality and functional standards.

AMS2460 is a standard specification by SAE Aerospace Material Specifications (AMS), defining requirements for electrodeposited chromium plating, commonly employed in aerospace, automotive, and commercial vehicles. The current active revision is Rev. B (AMS2460B), which supersedes AMS2460A, AMS-QQ-C-320. AMS-QQ-C-320 is equivalent to 2460, but more stringent than 2406.

AMS2460 outlines two main classes of chromium plating, each catering to diverse needs and applications:

Class 1: Corrosion Protective Plating

Objective: Primarily aims at corrosion protection, this class also emphasizes aesthetic appeal.

Appearance: Subdivides into two types of appearance – Type I offers a bright finish while Type II renders a satin finish.

Applications: Typically applicable for decorative purposes and where corrosion resistance is crucial, such as in automotive trims and fixtures.

Class 2: Engineering Plating

Objective: This class is synonymous with engineering or industrial chromium, focused on providing wear resistance, abrasion resistance, and improved frictional properties.

Appearance: Lacks the brightness of Class 1, emphasizing more on functional attributes than aesthetics.

Applications: Predominantly used where the functional attributes of the plating are paramount, like in industrial equipment and machinery components.

Details & Specifications

Class 1 Plating: Specifies nominal plating thickness and distinctive forms like Form R and Form MP/MC, detailing requirements like pore density and crack frequency, pertinent for applications necessitating oil or lubrication retention on the chrome surface.

Class 2 Plating: Details specifications on underplating, thickness, and designations like 2b, 2c, 2d, and 2e based on hardness and treatment prerequisites of the parts, ensuring meticulous compliance and optimal functional performance in varied environments.

Compliance & Standards Reference: Incorporates ARP4992 for processing solutions’ control and ASTM B374 for design definition and technical interpretation, providing comprehensive resolutions and clarity on standards compliance.

Conclusion

AMS2460B is a comprehensive guide that meticulously categorizes and details the processes and requirements for electrodeposition of chromium plating. It is integral for industries requiring precise specifications for corrosion resistance and engineering applications, ensuring the optimum balance between aesthetics and functionality.

The AMS 2403 specification provides a comprehensive guide for the electrodeposition of nickel, designed to enhance corrosion resistance and surface properties of various metals. This industry-standard document is pivotal for manufacturers and engineers seeking to apply a general-purpose nickel plating, balancing precision and quality in metal finishing processes.

Key Highlights of AMS 2430N Specification

Purpose & Application: AMS 2430 is crucial for achieving moderate corrosion and oxidation resistance on metal parts, distinguishing itself from other specifications like AMS 2438 (hard plate) and AMS 2424 (low-stress plate) based on stress requirements in plating processes.

Preparation & Process Guidelines

Stress Relief Treatment: For parts above 40 HRC, stress relief at specific temperatures (275°F for 5 to 10 hours for ≥ 55 HRC, 375°F for 4 hours minimum for <55 HRC) is necessary.

Surface Cleaning: Ensuring parts are free of contamination before immersion in the plating solution.

Electrodeposition: Nickel is deposited from a specified plating solution, with strict controls on additives to maintain the integrity of the plate and the base metal.

Temperature & Thickness Control: Specifies precise temperature ranges for stress relief and plating processes, ensuring adherence and quality.

Detailed thickness requirements for different applications, from minimal coverage of approximately 0.0001″ (flash plating) to substantial uniform thickness.

Quality Assurance: Emphasized rigorous inspection and testing protocols, including acceptance for thickness, periodic tests for heat resistance, corrosion resistance (ASTM B117), hydrogen embrittlement (ASTM F519), and pre-production tests.

Specifies the sampling procedures and testing methodologies to ensure compliance with the standard.

Delivery & Handling: Outlines procedures for handling, packaging, and preparing plated parts for shipment, maintaining the integrity of the plating.

Additional Information

Offers notes on manufacturing operations that may affect plating quality.

Advises on substrate condition and surface activation for optimal plating results.

Presents dimensions and properties in both inch/pound and SI units for global compatibility.

Conclusion

AMS2403 is a cornerstone document for nickel plating, ensuring superior corrosion resistance and surface properties. It is an invaluable reference for the metal plating industry, guiding engineers and manufacturers to meet high-quality standards and achieve the desired performance of plated components.

AMS 2404 is a detailed specification for electroless nickel plating, providing guidelines for nickel-phosphorus coatings on various substrates. This specification is critical for industries requiring high wear resistance, corrosion protection, and improved solderability, particularly in high-temperature applications up to 1000 °F (538 °C).

Key Features of AMS 2404:

Classification & Applications:

AMS 2404 classifies coatings into four classes, each with distinct post-plating thermal treatment criteria. These classes cater to a broad spectrum of industrial applications, ensuring versatility in usage.

Preparation & Stress Relief:

It emphasizes proper surface preparation, including detailed stress relief guidelines for different hardness levels of parts to bel plated. This ensures the longevity and durability of the coating.

Plating Procedure:

The specification covers the entire plating process, from surface preparation to chemical deposition of nickel-phosphorus and post-treatment processes such as hydrogen embrittlement relief and heat treatment for hardness or adhesion enhancement.

Minimum Thickness Requirement:

It outlines specific minimum thickness requirements for the nickel coating on different base alloys, ensuring the efficiency and effectiveness of the coating in various applications.

Quality Assurance & Testing:

AMS 2404 mandates rigorous testing and inspection protocols. It includes guidelines for acceptance, periodic, and preproduction tests, and detailed sampling procedures to ensure compliance with quality standards.

Handling & Packaging:

The specification includes recommendations on the handling and packaging of plated parts to maintain their integrity and properties.

Additional Guidelines:

It also offers guidance on part manufacturing operations, special surface preparation techniques, and advises on substrate condition for optimal plating results.

By adhering to the AMS 2404 specification, plating companies can guarantee high-quality, durable, and consistent electroless nickel plating for various industrial applications. This specification ensures superior plating standards, making it an indispensable resource for the metal plating industry.

ASTM B117 is a globally recognized standard developed by ASTM International, providing a method for the Salt Spray (Fog) Testing of coated and uncoated materials. The primary scope of this standard is to offer a controlled corrosive environment for testing the material’s or coating’s resistance to corrosion. This standardized test aids industries – particularly automotive, aerospace, and coating sectors – in evaluating a product’s longevity and robustness under severe conditions, ensuring quality and durability.

Requirements

The requirements of ASTM B117 entail maintaining a specific chamber temperature (35°C or 95°F), a 5% NaCl solution concentration and set orientations for sample placement. The test duration can vary based on the material’s inherent corrosion resistance, ranging from 24 hours to over 1000 hours. Post-testing, samples undergo an evaluation process for signs of rust, corrosion, or alterations in color and gloss. It’s crucial to note that the ASTM B117 test is comparative and accelerated, predicting performance but not providing an exact lifespan in real-world conditions.

In relation to ASTM B117, other corrosion testing standards may be considered based on specific requirements, such as ASTM G85 for modified salt spray testing or ISO 9227, the international equivalent of ASTM B117.

ASTM D4060, “Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser,” sets out a pivotal testing method within the thin dense chrome plating industry. The primary focus of this standard is determining the abrasion resistance of organic coatings, a factor paramount to assessing the durability of chrome platings.

Requirements

This method requires the coating specimen to be mounted on the Taber Abraser’s turntable, subjected to a defined abrasion process with two abrasive wheels. The specimen undergoes rotation under specified pressure, creating a standardized wear pattern. The abrasion resistance is typically evaluated by measuring the loss of weight after a set number of cycles, revealing the wear resistance of the coating.

Through the application of ASTM D4060, the thin dense chrome plating industry can quantitatively evaluate the robustness of chrome coatings under abrasive conditions.

The ASTM B650 Standard Specification for Electrodeposited Engineering Chromium Coatings on Ferrous Substrates is a detailed guideline for applying chromium coatings to ferrous alloy substrates, primarily for engineering applications. This standard specifies the requirements for these coatings, which are often referred to as functional or hard chromium due to their significant thickness compared to decorative chromium.

Key Aspects of ASTM B650

Scope of Application:

The specification is focused on ferrous alloys, which are used in various engineering applications. It covers the essential requirements for electrodeposited chromium coatings.

Purpose of the Coating:

The primary reasons for applying these chromium coatings include:

• • Increasing wear and abrasion resistance
  • Reducing static and kinetic friction
  • Minimizing galling or seizing in metal combinations
  • Improving corrosion resistance
  • Building up undersize or worn parts

Classification of Coatings:

The standard classifies the coatings based on their thickness:

• • Class 1: Coatings with a thickness ranging from 2.5 to 25 µm
  • Class 2: Coatings with a thickness greater than 25 µm

Safety and Health Practices:

While the standard outlines the technical requirements for chromium coatings, it also emphasized the importance of safety and health practices. It is the user’s responsibility to establish appropriate safety measures and to be aware of any regulatory limitations associated with the use of this standard.

Latest Revision: The most current revision of the ASTM B650 standard at the time of this information is Rev. 95 (ASTM B650-95).

This standard plays an essential role in ensuring the quality and consistency of chromium coatings in engineering applications, addressing both the technical aspects of the coatings and the safety concerns associated with their application.

The ASTM B578 Standard is a comprehensive guideline for testing the microhardness of metallic coatings, particularly those applied on various substrates through electroplating. This standard is instrumental in determining the hardness characteristics of these coatings, which is crucial for understanding their wear resistance, durability, and overall performance in various applications. Below is an overview of the ASTM B578 Standard Test Method for Microhardness of Electroplated Coatings.

Key Features of ASTM B578 Standard

Scope and Application:

The ASTM B578 standard outlines the method for measuring the micro indentation hardness of metallic coatings on different substrates. These coatings are typically applied through electroplating processes.

Methodology:

The hardness testing is performed using a Knoop indenter. The Knoop hardness test is a microhardness testing method that involves pressing diamond-shaped indenter into the coating surface under a specific load and measuring the resulting indentation to calculate hardness.

Test Loads:

The hardness measurements are carried out under specific test loads. The standard specifies two test loads: 0.245 N (25 gf) and 0.981 N (100 gf). These specified loads help in ensuring uniformity and comparability in the test results across different samples and testing environments.

Reporting:

The outcome of the hardness test is expressed as a Knoop hardness number (HK). This number is a quantifiable measure of the material’s resistance to deformation, providing valuable information about the coating’s quality and expected performance in practical applications.

Scope and Limitations:

While this standard effectively determines the hardness of metallic coatings, it does not address all safety concerns related to its use. It is the responsibility of the users to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Current Edition:

The most recent edition of this standard, as of the available information, is the 2021 edition (ASTM B578-2021).

This standard is essential for industries where the hardness of metallic coatings is a critical factor in the performance and longevity of the coated products. It ensures a standardized approach to testing, aiding in quality control and material selection processes.

The ASTM F519 standard outlines a mechanical test method for evaluating hydrogen embrittlement in steel during the coating process. This is crucial for understanding the potential impacts of coating and plating processes on steel’s susceptibility to hydrogen embrittlement.

Key Aspects of ASTM F519

Test Principle:

Test specimens undergo tensile testing to determine their notched fracture strength (NFS). The acceptance criterion is that the NFS of each specimen must be within 10 ksi (69N/mm²) of the mean value. Subsequently, at least four notched specimens from the same batch undergo a 200-hour sustained load test (SLT). During this test, specimens must sustain the load for 200 hours under specific conditions.

Specimen Requirements:

Mainly notched specimens are used. If the notch angle of 60° does not allow for plating/coating of the notch root, an angle of 90° ±1° may be used, but only with prior approval.

Types of Specimens:

Various types of specimens are utilized, including notched, round, tensile load specimens (standard size and oversized), notched specimens with a self-loading fixture, and notched C-Ring specimens.

Testing Software Requirements:

Specific testing software is used to meet the requirements of ASTM F519. This software facilitates the detection of test interruptions due to specimen breakage, allows simultaneous testing of multiple specimens from different batches, and provides an intuitive operation for performing the test and evaluating the results.

Interpretation of Test Results:

If none of the four specimens break during the test, the plating/coating process is evaluated as non-brittle. If one of the four specimens breaks within the 200-hour period, it’s replaced with an unnotched dummy specimen, and the test continues with additional criteria for evaluation. Pre-existing specimen defects can be considered a basis for test invalidation.

In summary, ASTM F519 provides a comprehensive methodology to assess the risk of hydrogen embrittlement in coated or plated steel, offering a standardized approach to ensure the reliability and safety of such materials in various applications.

The ASTM B733 standard sets out guidelines for electroless nickel-phosphorus coatings on metal products. The standard is common for various engineering applications. These coatings are a blend of nickel and phosphorus. The coatings are created through a chemical process where hypophosphite acts as a reducing agent. This process is unique as the nickel alloy itself helps sustain the reaction.

The standard categorizes these coatings based on their phosphorus content, impacting their properties and uses:

Type-I: No set phosphorus requirement.

Type-II: 1 to 3% phosphorus, ideal for electronics due to its solderability and electrical properties.

Type-III: 2 to 4% phosphorus, known for high hardness and used in wear-resistant applications.

Type-IV: 5 to 9% phosphorus, the preferred choice for general wear and corrosion resistance.

Type-V: Over 10% phosphorus, offering excellent resistance to salts and acids, fitting for beryllium and titanium parts, and becomes non-ferromagnetic above 11.2% phosphorus.

Coating Thickness:

Coating thickness is also a key aspect, defined by service conditions from SC0 (minimum 0.1 µm thickness) for basic protection and conductivity needs, to SC4 for extreme conditions requiring strong wear and corrosion resistance.

Moreover, the standard outlines heat-treatment classes post-coating to enhance adhesion and hardness. These vary from Class 1 with no heat treatment, to class 6 which includes specific heat treatments for materials like titanium alloys to improve coating adhesion.

ASTM B733 ensures that electroless nickel-phosphorus coatings meet consistent quality standards, vital for their diverse industrial uses.

The ASTM A967 Standard Specification provides guidelines for chemical passivation treatments of stainless steel parts. This specification is crucial for ensuring the quality and longevity of stainless steel components, especially in applications where corrosion resistance is critical.

Key Aspects of ASTM A967

Types of Treatments:

It covers various treatments, including immersion in nitric acid or citric acid solutions and electrochemical treatment. After treatment, parts must be rinsed to stop the chemical reactions on the surface and to ensure a clean and passive film formation on the stainless steel.

Scope and Recommendations:

The specification includes recommendations for descaling, cleaning, and passivation of stainless steel parts. It acknowledges the practices for mechanical and chemical treatments of stainless steel surfaces and provides guidelines on selecting appropriate treatments for different stainless steel grades.

Testing Procedures:

Several tests are prescribed to confirm the effectiveness of passivation. These include the Water Immersion Test, High Humidity Test, Salt Spray Test, Copper Sulfate Test, Potassium Ferricyanide-Nitric Acid Test, Damp Cloth Test, and Boiling Water Immersion Test. These tests are crucial for ensuring the removal of free iron and other exogenous matter.

This standard is essential in various industries for maintaining the quality and corrosion resistance of stainless steel parts through effective passivation.

MIL-C-26074, aka AMS-C-26074, is a military specification for electroless nickel plating, crucial in high-specification industries like aerospace and defense. This specification outlines four classes and three grades.

Classes and Post-Treatments:

The classes (1-4) specify procedural changes or post-treatments required.

• • Class 1: As plated, no subsequent heat treatment
  • Class 2: Heat treated for required hardness
  • Class 3: For non heat-treatable aluminum and beryllium alloys, improving nickel deposit adhesion
  • Class 4: For heat-treatable aluminum alloys, also to improve adhesion

Grades and Thickness:

• • Grade A: 1000 microinches, for aluminum-based alloys
  • Grade B: 500 microinches, for copper, nickel, cobalt, titanium, and beryllium
  • Grade C: 1500 microinches, for iron-based alloys

Benefits:

Electroless nickel plating offers qualities such as higher ductility, corrosion resistance, lubricity, wear resistance, and versatility compared to electrolytic nickel. It can bond with any metal substrate without thickness limits and has higher hardness and abrasion resistance.

Base Metals:

The specification is applicable to iron, copper, aluminum, nickel, cobalt, beryllium, titanium, and their alloys.

Underplating Restrictions:

Silver or copper plus silver cannot be used as an underplate. When gold is applied to copper-rich surfaces like brass or bronze, an anti-diffusion underplate like nickel should be used.

This specification is vital for ensuring the quality and consistency of electroless nickel plating in military and aerospace applications, providing guidelines for the coating process, thickness, and post-treatment procedures.

AMS-QQ-C-320 is a historical specification that established the technical requirements for electroplated chromium coatings on metal substrates. Commonly used in aerospace, defense, and industrial applications, it defined the performance characteristics, material properties, and quality assurance processes required for chromium-plated components.

Key Elements of AMS-QQ-C-320

Plating Classes:

Electrodeposited chromium plating is categorized into Class 1 for corrosion protections (with Type I – Bright and Type II – Satin finishes) and Class 2 for engineering applications focuses on wear resistance.

Performance Requirements:

The specification outlined strict criteria for hardness, adhesion, and corrosion resistance. Chromium coatings were required to withstand rigorous operational conditions, including exposure to harsh chemicals and high-friction environments.

Application Methods:

The standard detailed the electroplating process, including surface preparation, plating bath conditions, and post-plating treatments. These steps were essential to achieving consistent and durable coatings.

Inspection and Testing:

Quality assurance was a critical component of AMS-QQ-C-320. Inspection procedures included thickness measurement, adhesion tests, and microhardness evaluation to ensure compliance with specified requirements.

Material Compatibility

The specification addressed the application of chromium plating to various base materials, including steel, aluminum, and other alloys, ensuring that the coating adhered properly and enhanced the substrate’s properties.

Transition to New Standards:

AMS-QQ-C-320 has been superseded by newer specifications, such as AMS 2460, which incorporate advancements in materials science and modern manufacturing practices. These updated standards offer improved consistency and performance while addressing environmental and regulatory considerations.

Despite its supersession, AMS-QQ-C-320 remains relevant for legacy systems and components designed under its guidelines. Engineers and manufacturers often reference this specification to maintain compatibility with older equipment or to understand the historical basis of current standards.