What are oil impregnated bronze bushings…

We get many calls regarding our oil impregnated bearing line. There seems to be some confusion with these products. This post should help you better understand oil impregnated bearings. These bearings are manufactured using the powdered metal process. This process ensures the uniform distribution of pores between the bronze particles which absorbs the oil by capillary action. In addition our bearings have a self-contained oil supply which provides a uniform protective film over the entire bearing surface.

Powdered Metal Process

There are several steps involved in how the powdered metal process works, but the end result can be a low-cost, high-quality powdered metal part. Listed below is the typical sintered metal casting process in order:

Blending – This is the process of combining metal powders or alloys together with lubricants to produce a homogeneous mix.

Briquetting – This process is where metal powders or alloys are compressed while restricted in a die, at pressures as low as 10 to 45 tons per square inch.

Sintering – Here each individual particle bonds into a mass. The parts are heated in a protective atmosphere furnace to a high relative temperature below the melting point of the particular metal or alloy.

Repressing – This is the final pressing of a sintered metal part to obtain proper size and physical properties.

Infiltrating – This process fills the pores of a sintered metal part with a metal or alloy of a lower melting point.

Impregnation – This process fills the pores of a sintered metal part with a lubricant.

Heat Treating – This is the heating of a sintered metal part in a protective atmosphere and then oil quenching the part. The results are usually improved strength and hardness.

Machining – If required powdered metal parts can be machined to obtain the desired shape before or after heat-treating is completed.

Sintered Bronze Flanged Bushing

Understanding the process required to manufacture oil impregnated bearings can help you understand the various limitations of the product. While oil impregnated bearings are not ideal for all situations, they are a great way to go if your requirements permit them. For more information on oil impregnated bearings and what will work for your project call one of our Sales Engineers at 800-875-3558 or by email at sales@nationalbronze.com

Small Oil Impregnated

How to order Bronze Bar Stock

There are a few basic points to know when ordering bronze bar stock. Understanding these points will make it easier when ordering your bronze requirements. Also knowing these rules will help eliminate costly mistakes and speed up your lead time on various jobs.
First and foremost is that there are many different types of bronze. Generally they are designated by a copper alloy number. The copper alloy number is usually preceded by a “C” or “CA”, as in C93200 or CA93200. The “CA” stands for copper alloy number, the number is designated by the Copper Development Association. Bronze can also be referred to by different trade names such as Wear rite 411. There are corresponding CA numbers that are equivalent to these trade names.

The second thing you should know when ordering bronze bar is that many of the types of bronze are cast slightly over sized. These sizes are listed by their nominal size. These types of bronze are made to be able to finish to their nominal size. For example if you are ordering a piece with a 4” outside diameter, the actual piece will be slightly oversized in order to finish to the 4 inch nominal size.

The final tip when ordering bronze is about how bronze tubing is listed. When ordering bronze tubing the inner diameter (ID) is listed before the outside diameter (OD). Many other metals are listed opposite of this with the OD first and either the wall thickness or ID second. Understanding these basic rules will help you with your future bronze ordering requirements. For any other questions feel free to contact any of our knowledgeable Sale Engineers at 800-875-3558 or by email at sales@nationalbronze.com