How To Make Your Graphite Oilless Bushing More Self-Lubricating?

In the realm of machinery and industrial applications, the quest for optimal performance often leads to innovations in materials and design. One such innovation gaining prominence is the use of graphite oilless bushings. These components play a crucial role in ensuring smooth operations, but the key lies in harnessing their self-lubricating capabilities effectively.

1. Choosing the Right Copper Material for Graphite Oilless Bushing

When it comes to self-lubricating bushings, not all copper materials are created equal. High-strength brass, aluminum bronze, and tin bronze are among the top choices. Each comes with its unique advantages and considerations. High-strength brass offers a cost-effective solution, while aluminum bronze and tin bronze provide enhanced performance at a higher cost.

Oil-Free Brass Bushings Used In Rolling Mills

High Strength Brass Bushing Material: ZCuZn25Al6Fe3Mn3 Alloy

The chemical formula for high-strength brass is ZCuZn25Al6Fe3Mn3, with approximately 65% copper and 24% zinc. The presence of zinc significantly enhances the alloy’s strength, hardness, and corrosion resistance.

Pressure Processing Characteristics:

High strength brass exhibits excellent plasticity, allowing it to withstand both cold and hot processing. However, during hot processing, such as forging, it may experience intermediate temperature brittleness. The specific temperature range for this phenomenon varies with the zinc content and typically occurs between 200 to 700°C. Therefore, it is advisable to maintain processing temperatures above 700°C to avoid this issue.

Mechanical Properties:

The mechanical properties of high strength brass vary with the zinc content. In the case of α-brass, as the zinc content increases, both the tensile strength (σb) and elongation (δ) continually rise. However, copper-zinc alloys with zinc content exceeding 45% have limited practical value. The standard high strength brass boasts a Brinell hardness (HB) greater than 200, compressive strength exceeding 600 MPa, and elongation greater than 10%.

Application Areas:

Due to its remarkable wear resistance, high strength, large hardness, and strong resistance to chemical corrosion, high strength brass finds applications in diverse industries. Common uses include the manufacturing of sheets, bars, rods, pipes, and cast components. Its machining properties make it a preferred material for various industrial applications where durability and reliability are crucial.

2. Selecting the Ideal Graphite Material

Contrary to popular belief, the graphite used in self-lubricating bushings is not “purely natural.” It is a product of meticulous craftsmanship involving the combination of graphite powder, polytetrafluoroethylene (PTFE) powder, and talc powder. The fineness of the graphite powder and the density of the pressing process significantly impact the final product’s performance.

3.Design Considerations for Maximum Lubrication

The design of self-lubricating bushings involves a delicate balance. The size of the graphite should match the inner diameter of the bushing, ensuring an efficient lubrication process. Additionally, the optimal percentage of graphite coverage on the inner surface is around 20%, striking the perfect equilibrium between lubrication and structural integrity.

4.Arrangement of Graphite for Different Motion Types

It’s a common misconception that a few drilled holes in the copper bushing filled with graphite will automatically result in self-lubrication. The reality is more nuanced, and the arrangement of graphite depends on the type of motion the bushing will experience. Rotational and linear movements require distinct graphite layouts, and one-size-fits-all solutions seldom live up to expectations.

Environmental Impact and Sustainability

Beyond the immediate benefits of self-lubricating bushings, it’s crucial to examine their broader impact on the environment. Reduced friction leads to lower energy consumption, aligning with the global push for sustainable manufacturing practices. Choosing self-lubricating solutions isn’t just a practical decision; it’s a step towards a greener, more sustainable future.