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SAE J460-2018: A Guide to Bearing and Bushing Alloy Compositions
Overview of the Standard
SAE J460-2018, stabilized in January 2018, specifies the chemical composition limits for various bearing and bushing alloys used in automotive and general engineering. The standard covers five tables: lead and tin-based alloys (Table 1), lead-based overlays (Table 2), copper-based alloys with steel backing (Table 3), copper-based cast alloys not bonded to steel (Table 4), and aluminum-based alloys (Table 5). Notably, it applies to finished bearings or linings, not intermediate stages, and all values not given as ranges are maxima.
🛠️ Stabilized Status: This standard has been declared stabilized, indicating mature technology with no anticipated changes. Users should verify continued suitability and consider newer alternatives.
Key Alloy Tables and Composition Highlights
The standard defines precise element ranges. The table below summarizes the alloy families and their primary constituents.
| Table | Alloy Type | Examples | Key Elements |
|---|---|---|---|
| 1 | Lead & Tin-Based | SAE 12, SAE 15 | Sn, Sb, Cu, Pb |
| 2 | Lead-Based Overlays | SAE 191, SAE 194 | Pb, Sn, In, Cu |
| 3 | Copper-Based (Steel Backed) | SAE 48, SAE 792 | Cu, Pb, Sn |
| 4 | Copper-Based (Cast) | SAE 791, UNS C93700 | Cu, Pb, Sn, Zn |
| 5 | Aluminum-Based | SAE 770, SAE 786 | Al, Sn, Si, Cu |
Design Insight: Alloy selection depends on application loads, speeds, and environment. For instance, SAE 16 (Table 1) uses a thin overlay on a sintered matrix for crankshaft bearings. Copper alloys in Table 3 are steel-backed for high-load use, while aluminum alloys offer lightweight and corrosion resistance.
⚠️ Common Mistake: Assuming all non-range values are not necessarily maxima. The scope explicitly states: “All values not given as ranges are maxima.” Also, note footnotes for allowed variations like Ni or Cr additions.
Frequently Asked Questions
What does it mean that SAE J460 is “stabilized”?
A stabilized standard indicates mature technology not likely to change. Users must verify continued suitability and consider newer technologies, but the compositions remain valid.
How do SAE 48 and SAE 49 differ?
SAE 48 (CuPb30) has higher lead (26-33% Pb) and lower tin (0.5% max). SAE 49 (CuPb24Sn) has 21-27% Pb and 0.6-2.0% Sn, offering different mechanical properties. Variants allow up to 2.8% Sn.
What should engineers consider when using lead-based overlays?
Overlays in Table 2 are typically thin layers (0.025-0.125 mm) for applications like crankshaft bearings. Impurity limits (Total Others: 0.5%) are critical, and ISO equivalents exist for some.
Are there ISO equivalents for all SAE designations?
Standard includes ISO equivalents for many alloys, but not all. Engineers should cross-reference specific element ranges, especially when sourcing globally.
