Supplier of Oil-impregnated Bronze Bearings and Powdered Metal Bearings, Offering Bronze Powdered Metal Material (Oil Impregnated).

Oil-impregnated bronze bearings, made from bronze powdered metal, begin their production journey through a pressing process, which is often the stage where the initial significant challenges of powdered metallurgy (P/M) arise. This process involves shaping the powder into desired forms, a crucial phase known as compacting or pressing.

Compacting or pressing is categorized into two main methods:

1. Hot Pressing: This involves compacting powder at high temperatures, typically integrating compaction and sintering simultaneously. It’s a method often reserved for specific applications, such as manufacturing carbide-cutting tools.
2. Cold Pressing: This method can be subdivided further into:
   • Axial Pressing (Conventional Pressing): A standard method of pressing.
   • Isostatic Pressing: A technique where pressure is applied evenly from all directions to the metal powders.

Cold pressing involves exerting pressure on a column of loosely packed metal powders within a closed die to create a green compact, a preliminary shaped part before sintering. This technique is prevalent in P/M, responsible for producing the majority of parts.

During the pressing process, metal powders do not behave like liquids; they don’t transmit pressure uniformly in all directions when compressed in a die. The flow of the powders and the resulting compaction are influenced by various factors, including the powder’s characteristics such as particle size, shape, and composition.

Achieving uniform density throughout the compact is crucial for dimensional consistency during subsequent sintering. The required pressure for compaction varies with the type of metal powder, and excessive pressure can lead to issues like fractures in the compacted part.

Post-sintering, a sizing or repressing operation might be necessary to achieve precise dimensions, especially for parts where high accuracy is essential. This step involves repressing the part to adjust dimensions altered during sintering.

The compacting process in P/M involves feeding powder into a die, compacting it into shape by applying pressure, and then extracting the formed part. Early presses, adapted from pharmaceutical and small stamping presses, lacked the necessary rigidity and adjustability, limiting the quality and complexity of producible parts.

Modern pressing equipment, available in various tonnages and designs, offers enhanced rigidity and accuracy. The majority of P/M parts are compacted mechanically, with mechanical presses preferred for lower pressure ranges due to their speed advantage over hydraulic presses. The selection between mechanical and hydraulic presses largely depends on the required energy source for compaction.

Metal powder pressing is a key process in the field of powder metallurgy, where a powder is compressed uniaxially between two presses to form a green body. This method is fundamental for creating precision and highly accurate parts by pressing powdered metals and alloys into a rigid die under pressure. The process encompasses powder mixing, compacting, and sintering, where the compacted powder is heated to a temperature below its melting point to fuse the particles into a solid piece. This technique allows the production of complex shapes that are challenging to achieve with traditional metalworking methods!