Sintered Metal Parts
Sintered metal parts are solid metal products made through a powder metallurgy process that features a sintering step, as opposed to a metal injection molding step. Sintering presses metal powder into a coherent mass without altering its shape by heating it below its melting point.
Quick links to Sintered Metal Parts Information
Sintered metal parts are used in a wide variety of industries, including:
- Automotive Engineering
- Military and Defense
- Lawn and Garden
- Food and Beverage
- Computers
- Electronics
- Hardware
- Bearings
- Bushings
- Frangible Shotgun Shells or “Breaching Rounds”
- Steam Filters
- Structural Parts
All powder metallurgy processes begin with the creation of metal powder from solid metal stock shapes or bars. This may be achieved in a number of different ways, most commonly:
- Atomization
- Centrifugal Disintegration
- Chemical Decomposition
- Grinding
Atomization Process
Most often, manufacturers choose to convert solid metal into powder using atomization. This is because, by separating molten metals into separate particles that then freeze into solid form, this process can effectively process nearly all met while powdered. A pure metal may be enhanced with another metal to make an alloy or with lubricant additives.
- Once a metal is turned into powder, it goes on to the forming portion of the process. During this step, the powdered metal is poured into a mold cavity or a die prefabricated in the shape of the desired part.
- Once inside, the metal is compacted under large amounts of pressure at room temperature until it becomes a solid shape. Note that the exact amount of pressure applied to the metal determines the malleability of the finished piece.
- After the second step is complete, the metal mass is removed from the mold and placed inside an extremely hot furnace. This part of the process is known officially as sintering.
- During sintering, the particles of the metal fuse together but do not melt, as the furnace is not healthy to the metal’s melting point.
- The result of sintering is a strong, porous, and rigid metal piece.
Secondary Processes
After a part has been sintered, manufacturers may choose to alter it using secondary processes. One of the most common alterations of sintered metal parts is a change in porosity. This is because the porosity of a part determines both its gas and liquid flow levels. To alter porosity, manufacturers may use a few different sealing techniques, including:
- Impregnation with a Plastic or Oil Resin
- Steam Filtration or Infiltration with a Metal that has a Lower Melting Point
Other secondary processes that sintered parts may undergo include those related to:
- Heating
- Sizing
- Deburring
- Machining
Bushings and bearings in particular, as well as other parts with very close tolerances, often must go through secondary sizing procedures.
Sintered parts can be created using all sorts of metals, including:
- Aluminum
- Brass
- Bronze
- Copper
- Nickel
- Stainless Steel
- Titanium
Furthermore, some metals that have very high melting points cannot realistically be machined unless they are machined—examples of those metals are carbon, molybdenum, osmium, rhenium, tantalum, and tungsten.
Types of Sintering
In addition to metal sintering, there are a few other types of sintering.
- Liquid Phase Sintering
- Electric Current Assisted Sintering
- Electro Sinter Forging
- Spark Plasma Sintering
- Plastics Sintering
- Pressureless Sintering
- Microwave Sintering
Benefits of Sintering
There are a number of reasons to create solid metal powder parts through sintering.
- It can nearly universally be applied.
- Sintering produces very little waste, with approximately 97% of the original material used to create a part ends up in the finished part.
- It is Cost-effective, especially during the fabrication of high volumes of metal parts and/or costly metal material parts.
- The sintering and powder metallurgy processes allow manufacturers to produce parts with relatively close tolerances, even in large quantities.
- Sintered metal parts can be fabricated with high levels of repeatability.
- Sintered metal parts display high levels of both magnetism and porosity, the latter which naturally dampens sound.
- Sintered parts are durable and, often, cannot be produced using any other method.
To find out more about sintered metal parts and how they may serve your application, reach out to an experienced powdered metal part manufacturer. For the best advice, talk to one of those manufacturers listed on this page. All of the companies with which we partner are knowledgeable, reputable and ready to assist you in your endeavors.