Sintered Bronze is not like a standard metal. It starts its life as a powder, it hardened, and then oil is added to its pores. It is used to operate many of the machines used today. Everything from a bushing for electric motors for items like a household blender to parts of assemblies in airplanes. Sintered Bronze parts are everywhere and help make the world turn, slide, and move.
What makes AMS-4805-E (previous designation SAE841) parts unique; is they start as a powder and are intentionally sintered to create porosity in the part. This porosity allows the parts to retain oil and wick that oil when in use. But it also means that you need to take care when machining these parts, so that they maintain their physical and mechanical properties.
Sintered Bronze can also be used to make custom parts and structural parts. Before there was 3D printing, there was Powder Metal Casting. And many parts used in Automotive and Yard Machines use structural parts because they are cost advantageous as opposed to machining those same parts from a sand casting, centrifugal casting, or continuous cast bar.
| Copper | Iron | Tin | Carbon/Graphite | Other |
|---|---|---|---|---|
| Balance | 1.0 Max | 9.5 - 10.5 | 0.3 Max | 1.0 Max |
| Property | Sintered Bronze (SAE 841) (CT-1000-K26) |
|---|---|
| Density (g/cm3) | 6.4 - 6.8 |
| Porosity (% by volume) | 19 Min. |
| App. Rockwell Hardness as Sintered (Ref. Only) | H-45 |
| L-Strength Constant | 26,500 |
Machining Sintered Bronze Parts
Machining must be done in a manner to preserve or enhance the physical and mechanical properties of the material. All efforts must be taken to maintain the porosity and avoid the closure of the surface microporosity. It is highly recommended that you use Carbide insert, dead sharp tools with the proper feed and speed rates. We do not recommend using Reaming tools as they typically smear/close the pores.
Cored and Solid Bars are available, but, when possible, start with a near net blank. This will allow at least one surface to remain untouched and the porosity maintained.
As another note, all oil impregnated parts should be reoiled after machining.
| Material | Speed (SFM) | Feed Rate (IPM) | Tool Nose Radius (Dim "R") |
|---|---|---|---|
| Sintered Bronze | 500 | .002" - .006" | .003" - .015" |
Sintered Bronze Parts Lubrication
Sintered Bronze can be used with many commercially available oils. As a standard, a high grade 100 viscosity, non-detergent, turbine oil is used, unless instructed. This turbine oil has an operational range from -10°F to +200°F. As mentioned, there are many custom oils also available for food grade and military applications (ie MIL-PRF-6085D, MIL-PRF-7808H, MIL-PRF-17331-H). Other options are also available.
Sintered Bronze Storage
Sintered Bronze must be stored in a non-absorbing container. So, you cannot store these in cardboard, cloth, or a paper product. Generations ago, this meant all sintered bronze parts were stored in steel contains, which was heavy and cumbersome. With the proliferation of plastics, storage in a plastic bag is common practice today. Over time oil will wick away from the part, regardless of the storage medium. It is recommended that you reoil the parts after long term storage.
Sintered Bronze Shaft Material Recommendations
The shaft of the mating part should be made from SAE 1137 or SAE 1141. Other steels containing at least 0.4% carbon may also be used. Hard Chromium plating is recommended if corrosion is a concern. The shaft should have an RMS between 4RMS to 10RMS. If you are going to use a stainless-steel shaft, then we will want to use a specialty or synthetic oil to prevent premature wear.
Sintered Bronze Surface Finish
Sintered Bronze Bar, Cored Bar, and Plates are oversized to finish to the dimensions noted. Sleeve and Flange bushings have an appearance of 63 RMS but are actually 125RMS.