Understanding Sleeve Bearings

So many bearings, so little time! We’ve previously written about different types of bearings and how bearings work, but today we’re going to hone in on one specific type of bearing we manufacture at Atlas Bronze: the sleeve bearing.

What Are Sleeve Bearings?

Sleeve bearings may come in a different form than other kinds of bearings, but they have the same purpose: to reduce friction between two or more moving parts. Bearings bear the load and force of one moving part on another, allowing both simple and complex machines to run smoothly, preventing wear and tear from friction.

As their name suggests, sleeve bearings are quite literally sleeves made of plastic, metal, or fiber-reinforced composite material. Sleeve bearings slide between two moving parts, absorbing friction and reducing both noise and vibration. 

Sleeve Bearing Basics

A sleeve bearing that’s made with metal is typically comprised of steel, bronze, graphite, or brass. As discussed above, polymer plastic and composite sleeve bearings are an option as well, but their use is limited to specific applications, while metal bearings are more widely used. Any material used to make sleeve bearings must be durable, low friction, resistant to corrosion, and able to withstand high temperatures.

To further reduce friction, some sleeve bearings come complete with lubricant plugs to ensure smooth motion between parts. Another option is an oil-impregnated bronze sleeve bearing, a unique solution that releases oil when under pressure, then absorbs it back into tiny pores when the pressure is released.

It should also be mentioned that sleeve bearings are sometimes marketed as bushings, plain bearings, or journal bearings. No matter what name they go by, their purpose and design is the same.

When to Use Sleeve Bearings

Of all bearing types, sleeve bearings are one of the more affordable options. They’re also easier to maintain and install. Choose sleeve bearings for any application in which you want to reduce noise, friction, and vibration in a cost-effective manner.

Sleeve bearings differ from ball bearings in that they have a higher load capacity thanks to their larger contact area. While the force exerted on a ball bearing is applied to the single point where the bearing is in contact with a surface, sleeve bearings are wider, giving them increased shock load resistance and capacity.

Sleeve Bearing Design

There are a few different sleeve bearing designs to choose from, each suited to different applications. The most common types of sleeve bearings are flanged sleeve bearings and cylindrical sleeve bearings. Cylindrical bearings are exactly what they sound like––straight cylinders with the same diameters throughout and flush inside the housing. A flanged sleeve bearing is a cylinder with a flange at the end. This provides a bearing surface for axial loads.

Learn More About Atlas Bronze Sleeve Bearings

To learn more about ordering high-quality sleeve bearings from Atlas Bronze, contact us at 1-800-478-0887. Our sales team offers customers unparalleled support and knowledge, and we’re committed to working with you to find the best products to suit your needs.

Should I Choose Bronze or Brass for My Application?

Our customers use bronze and brass for many different purposes. Whether it's industrial uses like parts for factories and machinery or consumer goods like jewelry and home appliances, you want to make an educated decision about which alloy is best for your application.

Bronze is typically made with a combination of copper and aluminum, tin, or magnesium, while brass uses copper as the base, which is then combined with zinc. But other than the metals used to make these alloys, what is the difference between brass and bronze?

Here's what to consider when deciding between bronze or brass for your application.

Strength

One of the first factors to think about is the strength you need for your application. For industrial purposes, like machinery, you will likely want to choose a stronger alloy. If you're fabricating pieces for consumer use, strength may not be as important as other factors like appearance and resistance to corrosion. When brass and bronze are cold worked, their tensile strength increases; you can also increase the tensile strength of brass by adding a higher percentage of zinc.

The tensile strength of brass is 53 Ksi (365 Mpa) when annealed and 88 Ksi (607 Mpa) when cold-rolled tempered. When annealed, phosphor bronze has a tensile strength of 50 Ksi (345 Mpa), while cold-rolled tempered brass comes in at 92 Ksi (635 Mpa).
Formability

Another important question to ask is what you're going to be doing with the alloy you purchase. Will it need to be formed? How will it be worked? When it comes to brass, the percentage of zinc present in the alloy impacts its formability. A lower amount of zinc gives brass good hot working capabilities, but makes it harder to cold work. On the other hand, with a higher amount of zinc, brass is more ductile when worked at room temperature.
Corrosion and Wear

Durability and resistance to corrosion are two other factors to think about. If your alloy will be used in water or in a humid environment, tin brass is an excellent choice. For a material that resists both wear and corrosion, we suggest aluminum bronze cast alloys or silicon bronze.
Conductivity

For industrial applications, you may need to find an alloy that conducts electrical currents or thermal heat. In this case, you should evaluate the material’s International Annealed Copper Standard, or IACS, value for conductivity. A higher number means higher conductivity.
Aesthetics

When you are using an alloy to manufacture consumer goods, you will want to think about appearance as well as the other factors discussed above. What do you want the end-product to look like? Brass comes in a range of colors, from yellows to reds, while bronze is available in white, rich browns, and shades of gold. When treated with chemicals or heat, you can obtain a patina too, which may be desirable for jewelry and sculptures.

Talk to Our Brass and Bronze Experts

Before making any decision, it's best to consult with an expert. Our skilled metallurgists can help you choose the right alloy for your application. Give us a call at 1-800-478-0887.

How Brass Is Made

An alloy of copper and zinc, brass is typically a muted gold color, though this may be affected by the amount of zinc in the alloy. It is often confused with bronze, which is an alloy of copper and tin. Brass is reasonably hard, strong, and malleable. It is an excellent heat conductor and imparts excellent acoustic properties to musical instruments. Brass is somewhat corrosion resistant, and it can be made more so through the addition of iron, silicon, aluminum, and/or manganese to the alloy.

Besides musical instruments, brass is often used for piping and tubing, architectural trim, boat hardware, screws, and such low-friction applications as zippers, gears, doorknobs and locks, valves, and ammunition. It is not prone to sparking, making it an excellent choice for tools and fittings that will be used around explosive gases.

The Manufacturing Process

Brass stock is available in a variety of different forms, depending on the final product that will be made. For example, brass pipes and tubes are made by extruding rectangular billets of hot brass through a die, while brass screws are cut from a piece of brass rod. Therefore, the exact manufacturing process will vary depending on the form of brass stock that is being created. Still, the majority of the process is the same until the final steps.

Steps to Manufacturing Brass Sheet

Brass sheet is a flat, rectangular piece of brass that can be cut into strips. It is a very common raw material, and its manufacturing process is an excellent representation of how all brass is made:


Step 1 – Melting: The first step is to melt the copper alloy at a temperature of approximately 1050 C. Additional zinc may be added to account for vaporization during melting. If other materials will be included, such as iron or manganese, they are added in this step.


Step 2 – Molding: The molten metal is then poured into molds measuring 8 inches x 18 inches x 10 feet and cooled into cakes.


Step 3 – Storage: The cooled cakes are removed from the molds and stored near the rolling area until needed.


Step 4 - Reheating: The cake is reheated in a furnace to the appropriate temperature, which will vary based on the desired final properties of the brass stock.


Step 5 - Hot rolling: The heated cake is fed through opposing steel rollers to increase its width and reduce its thickness to 0.5 inch or less.


Step 6 – Scalping: A milling machine known as a scalper removes a thin slice from each outer face of the brass to remove oxides that developed from exposure to the air while the brass was hot.


Step 7 – Annealing: In a process known as annealing, the brass is reheated in a furnace filled with nitrogen or another neutral gas to restore ductility, or the ability to stretch. The exact temperature varies, but it is much lower than the original reheating temperature.


Step 8 – Cold rolling: The brass is fed through another set of rollers, reducing its thickness to approximately 0.1 inch. This cold rolling process increases hardness and strength by deforming the grain, or internal structure, of the brass.

Steps 7 and 8 may be repeated one or more times to achieve the desired final properties.

Optional Steps

Step 9 – Stripping: If desired, the brass sheet may be passed through a cutting machine to create strips. Each strip is typically cleaned in an acid bath and then rinsed.


Step 10 – Finish rolling: The brass sheet or strip may be cold rolled once more to tighten tolerances and improve the smoothness of the surface.

Ready to Start?

Atlas Bronze is a leading U.S. distributor of bronze, copper, brass, iron, and more. Contact us today at 1-800-478-0887 to place an order or learn about our custom products.