Advantages of Powder Metallurgy (PM) and How It Compares To Other Manufacturing Methods

• A unique or complex shape that would be impossible, costly, or impracticable to manufacture using other metal forming technologies.
• Part-to-part reproducibility and repeatability with tight dimensional requirements over moderate to high volume applications.
• Long-term reliability in critical applications.
• Controlled porosity for self-lubrication
• Unique requirements that may be solved with the appropriate material selection and processing strategies.
• Specific strength, wear resistance, and surface finish requirements.
• Cost competitive through reduced material losses and eliminating or minimizing secondary operations such as machining.

Casting is the process where molten metal is injected into a mold and allowed to harden to form the part. The materials used are normally non-ferrous, primarily aluminum, magnesium, and zinc alloys.

The decision to use a specific metal forming technology is dependent on part complexity, specific mechanical requirements and application, production volume and part life, and cost consideration.

Advantages of the selection of Powder Metallurgy over Die Casting include:

• Design flexibility utilizing casting is limited by the need for draft angles, parting line considerations, and wall thickness, whereas the powder metal process allows for complex shapes and intricate features, and, when appropriate, controlled porosity.
• The need for specific production volumes and part life are both excellent using the die-casting process or the powder metallurgy process; however, powder metal provides better material utilization, as there is very little waste generated.
• The investment in the die and the tools in the Die Casting process can be expensive, whereas the cost of the tools used in powder metal can range from very inexpensive to expensive depending on the part geometry, the material used, and size.

Forging is the process of producing metal parts through mechanical deformation using compressive forces where the part is shaped without removing or adding material. Almost any type of metal or combination of metals can be forged. Selecting the correct material depends on the part's requirements in its application. The most common materials are stainless steel, titanium, carbon steels, and other metal alloys.

The decision to use a specific metal forming technology is dependent on part complexity, specific mechanical requirements and application, production volume and part life, and cost consideration.

Advantages of the selection of Powder Metallurgy over Forging include:

• Design flexibility utilizing forging is limited by the size of the press, and the ability to produce simple shapes, whereas the powder metal process allows for complex shapes and intricate features, and, when appropriate, controlled porosity.
• The need for specific production volumes and part life are both excellent using the forging process or the powder metallurgy process; however, PM provides better material utilization, as there is very little waste generated. Forging, although producing a strong final part, typically requires machining to provide an appealing finished product.
• The capital investment is significant in the forging process for the die and the press. Additionally, labor, tooling, and material costs may need to be considered. The cost of the tools used in powder metal can range from very inexpensive to expensive depending on the part geometry, material used, and size.

Stamping is the process of producing metal parts by pressing or punching metal sheet (or coiled metal) with a stamping press using a tool and die to form the part. Almost any type of metal or combination of metals can be forged. The selection of materials to use in this process is determined by the application, formability, welding requirements, corrosion resistance, strength, and cost.  The most common materials are aluminum, stainless steel, carbon steels, and copper and brass.

Advantages of the selection of Powder Metallurgy over Stamping include:

• Design considerations utilizing the stamping process include knowledge about how the metal will be deformed, as well as required radii, angles, and dimensional requirements. The powder metal process allows for complex shapes and intricate features not normally available through stamping.
• High-volume production is suitable for stamping and powder metal processes; however, stamping produces a considerable amount of excess material (scrap), where PM provides better material utilization, as there is very little waste generated. 
• The capital investment/ as well as high set-up costs are significant in the stamping process as stamping dies are expensive and increase in cost as the part becomes more complex. The cost of the stamping machines can also be costly, which further impacts the overall cost of production. The cost of the tools used in powder metal can range from very inexpensive to expensive depending on the part geometry, material used, and size.

Machining is a general term that covers many processes to remove material from a solid metal blank to produce the desired part. Examples of common machining processes are CNC turning, laser cutting, water jet cutting, and milling. The decision to use the machining process and the material selected depends on the finished part's complexity, the application's dimensional and tolerance requirements, and the volume and timeframe needed to manufacture the finished component. Depending on the above considerations, materials used in the machining process include aluminum, brass, bronze, copper, carbon steel, stainless steel, tool steel, alloys, and in some cases, plastics.

As part of producing a finished part, a machining process is often used in combination with powder metallurgy, forging, die casting, and stamping. It is often considered a secondary operation to those metal-forming technologies.

Advantages of the selection of Powder Metallurgy over Machining include:

• Powder metallurgy allows for complex shapes and intricate detail in a less costly manner, as there is minimal waste and better material utilization. However, a machined part may have superior dimensional accuracy, tighter tolerance, and improved surface finishes. 
• Depending on the machining process selected, cutting tools are expensive, and the lead times are often long. The ability to meet high production volumes with a machining process is limited by the machining process selected.