High Strength Brass Bushing

Summary of High Strength Brass Bearings with Graphite

Chemical Composition

The chemical composition of C86500 Manganese Bronze is as follows:

• Copper (Cu): 55.00-60.00%
• Tin (Sn): 1%
• Lead (Pb): 0.4%
• Zinc (Zn): 36.00-42.00%
• Iron (Fe): 0.40-2.00%
• Nickel (Ni): 1.0%
• Aluminum (Al): 0.50-1.50%
• Manganese (Mn): 0.10-1.50%

High strength brass bearings embedded with graphite are engineered for high load, low-speed applications without requiring external lubrication. These bearings are particularly effective due to their high tensile brass composition (CuZn25Al6Fe3Mn3) and the incorporation of graphite as a solid lubricant. The main advantages include:

• Self-Lubrication: Graphite within the brass matrix reduces friction and wear, eliminating the need for external lubrication.
• High Load Capacity: Designed to support significant loads, suitable for heavy-duty machinery in continuous casting, mining, and injection molding.
• Temperature and Corrosion Resistance: These bearings perform well under extreme temperatures and in corrosive environments, making them ideal for the marine industry and port equipment.
• Reduced Maintenance: The self-lubricating nature minimizes maintenance, reducing downtime and operational costs.

Applications

• Marine Industry: Used in environments requiring corrosion resistance and minimal lubrication.
• Port Equipment: Ideal for heavy-duty applications due to their high load capacity.
• Continuous Casting Mills: Suitable for high-temperature and load conditions.
• Mining Machinery: Effective in demanding conditions due to their strength and wear resistance.
• Injection Molding Machinery: The maintenance-free nature is beneficial for high-precision operations.

Impact of Maintenance-Free Feature

The self-lubricating property of these bearings significantly lowers maintenance requirements, which in turn reduces operational costs by decreasing downtime and minimizing labor involved in upkeep.

Suitability for Marine Environments

Yes, high strength brass bearings with graphite are suitable for marine environments. Their corrosion resistance and self-lubricating properties make them ideal for this application, ensuring durability and consistent performance under challenging conditions.

High-Strength Brass

Chemical Formula: ZCuZn25Al6Fe3Mn3

Mechanical Properties: The mechanical properties vary depending on the zinc content. It has good plasticity and can withstand both hot and cold processing.

Overview

High-strength brass is a type of special brass composed of multiple elements, such as aluminum, lead, tin, manganese, nickel, iron, and silicon. It is known for its excellent wear resistance, high strength, hardness, and strong resistance to chemical corrosion. Additionally, it has superior machinability. This brass is often manufactured into sheets, strips, bars, tubes, and cast parts.

Chemical Composition

High-strength brass has a chemical formula of ZCuZn25Al6Fe3Mn3, containing approximately 65% copper and 24% zinc. Zinc improves the strength, hardness, and corrosion resistance of brass. Brass has three types of microstructures at room temperature, depending on the zinc content. Brass with less than 35% zinc has a single-phase α solid solution microstructure, known as α brass.

Processing Properties

High-strength brass possesses good plasticity, allowing it to undergo both hot and cold processing. However, during forging and other hot processing methods, it can exhibit intermediate temperature brittleness, which varies with the zinc content, typically occurring between 200°C and 700°C. Therefore, the processing temperature should be above 700°C.

Mechanical Properties

The mechanical properties of high-strength brass vary with the zinc content. For α brass, both the tensile strength (σb) and elongation (δ) increase with higher zinc content. Copper-zinc alloys with more than 45% zinc have no practical value. Standard high-strength brass has a Brinell hardness (HB) greater than 200, compressive strength over 600 MPa, and an elongation greater than 10%.

Historical Development

The term “brass” first appeared in the Western Han dynasty, in texts like Dongfang Shuo’s “Shenyi Jing.” The exact type of copper alloy referred to is still uncertain. References to “green copper” and “yellow copper” in historical texts referred to ore colors and smelted products rather than specific copper-zinc or copper-tin alloys. By the Ming dynasty, “brass” specifically referred to copper-zinc alloys. The production of brass coins began later than other copper alloys due to the difficulty in obtaining metallic zinc. Zinc oxide reduces to metallic zinc at high temperatures, but it exists as vapor and reoxidizes when cooled, requiring special condensation equipment.

Archaeological findings show that early brass objects with zinc content over 20% were unintentionally obtained from copper-zinc ores. In the Shang and Zhou dynasties, the zinc content in copper objects was typically low. Some coins from the Western Han period contained zinc, but these were exceptions and likely resulted from using copper-zinc ores.

Applications

High-strength brass is widely used in making bushings and bearings. Solid lubricated oil-free bearings, made from high-strength brass, feature a matrix embedded with ordered cylindrical polymer fillers, such as graphite, molybdenum disulfide, PTFE, and lubricating oil. These bearings combine the high load capacity of brass with the reduced friction of non-metallic materials, achieving oil-free lubrication and significantly improving friction and wear performance. They offer advantages like good machinability, high precision, strong load capacity, and excellent wear resistance. Applications include joints in construction machinery, such as excavators, mining shovels, rotary drills, concrete pump trucks, rock drilling machinery, winches, port cranes, metallurgy machinery, continuous casting machinery, water conservancy machinery, conveying machinery, rolling mills, bottle blowers, crosshead locking differentials, tire vulcanizers, trailer balance beams, and vacuum switches.