Overview
EN ISO 2739:2012 is an internationally recognized standard developed by ISO/TC 119 "Powder metallurgy" that specifies a precise method for determining the radial crushing strength of sintered metal bushings. This standard applies to sintered metal parts shaped as hollow cylinders-commonly known as bushings-made from pure or alloyed metal powders. Updated to replace the 2010 edition, this version provides clear guidance on testing procedures, equipment requirements, and calculations for evaluating mechanical robustness under radial load.
Key Topics
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Scope and Applicability:
The standard is applicable to sintered bushings without flanges, notches, drilled holes, or keyways, whether oil-impregnated or not. It defines how to properly prepare and measure test specimens made from metal powders.
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Testing Principle:
Radial crushing strength is determined by applying a steadily increasing radial load to a hollow cylinder until fracture occurs or a maximum deformation of 10% of the diameter is reached.
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Apparatus Requirements:
- A pressing apparatus to apply radial load.
- A load measuring device accurate to 0.1% of full scale.
- Two flat, ground hardened steel loading plates, ensuring parallelism and sufficient size for the specimen.
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Measurement and Calculation:
Measurements of external diameter, internal diameter, length, and wall thickness are made under specified tolerances before testing. The radial crushing strength is calculated using the formula:
[
K = \frac{F}{2Le}(D - e)
]
where:
- (K) = radial crushing strength (N/mm²)
- (F) = maximum applied load at fracture (N)
- (L) = length of the cylinder (mm)
- (D) = external diameter (mm)
- (e) = cylinder wall thickness (mm)
This formula is valid when the wall thickness to diameter ratio (e/D) is less than 1/3.
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Precision and Repeatability:
The standard includes precision data to ensure reliable and reproducible results across different laboratories, citing repeatability and reproducibility values for specific materials.
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Test Reporting:
Detailed reporting requirements include the test reference, specimen identification, manufacturing details, oil impregnation status, machining, exact test results, and any factors potentially affecting accuracy.
Applications
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Quality Control in Powder Metallurgy:
EN ISO 2739:2012 is essential for manufacturers of sintered metal bushings to verify the mechanical integrity of their products, ensuring they meet strength requirements for industrial applications.
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Engineering Design Validation:
Engineers use radial crushing strength data to select appropriate sintered metal bushings for applications requiring resistance to radial compressive loads, such as in automotive, machinery, and aerospace components.
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Material Development:
Researchers and developers of new alloyed metal powders apply this standard to assess how modifications in metal composition or sintering parameters affect mechanical performance.
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Comparative Testing:
Enables standardized comparison of sintered metal materials between suppliers or production batches, supporting consistent product quality and regulatory compliance.
Related Standards
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ISO/TC 119 Series:
Covers a range of standards related to powder metallurgy testing methods and sampling procedures.
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MPIF Standard 55:
Provides additional guidance on radial crush strength testing, which this ISO standard references and incorporates for precision data.
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ISO 4498:
Specification for sintered bronze and iron bushings, often used in conjunction with mechanical testing standards to ensure overall product quality.
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ISO 6538:
Test methods for measuring hardness and mechanical properties of sintered metal powder components.
Keywords: EN ISO 2739:2012, sintered metal bushings, radial crushing strength, powder metallurgy testing, mechanical testing of metals, sintered powder metal parts, radial load testing, bushing durability, metal powder components, standardized testing methods
