Choosing the Right Process for Your Powder Production Line

Choosing the Right Process for Your Powder Production Line

Powder Production Line is a manufacturing process that creates metal components. It uses a range of processes to convert raw materials into a powder form, including the most common process, melt atomization.

Powder metallurgy offers superior dimensional accuracy. This allows for reduced machining needs and lowers the overall project cost.

Choosing a Process

When establishing a powder production line, choosing the right process is an important step. This is because the metal powder used for a particular application depends on its composition, properties and processing steps.

For instance, a metal powder produced for use in a Cold Spray machine will require a different raw material composition than a metal powder for a conventional sintering process. The same goes for the powder morphology and particle size distribution.

The shape index and aspect ratio of the powder particles are also important to understand, as they determine how the powder is able to be shaped. These characteristics are measured by comparing the particle shape to a perfect sphere.

The size of a powder particle is defined by its particle size distribution (PSD). There are many methods to measure PSD, including laser infraction, sieve pans and liquid suspension. The PSD provides the high, Powder Production Line median and low ranges of particle size composition for a given powder sample. This helps manufacturers to identify the most appropriate powder size for a particular application. The PSD is often used to qualify the quality of a powder.

Preparation

There are four different steps in the powder metallurgy process: preparation, mixing and blending, compacting and sintering. Each step requires specialized equipment to achieve positive results.

The first step in the process is to prepare the metal for use as powder. This can be done by chemical or atomization processes. In the chemical process, metal ore is crushed and mixed with carbon. This is then put through a furnace to create a reaction that reduces the oxygen and carbon content. This is then sieved to produce the powder.

Atomization is another popular way to make metal powders. This is usually accomplished by a jet of liquid metal intersected with high-speed streams of atomized water. This produces irregular sponge-like particles that are soft and easily compressible.

This technique also allows for a greater level of control over the density of a component. This is important because the density of a part can influence its strength, ductility and hardness. It can also make it easier to identify non-metallic inclusions and cross-contamination. The density of a part is measured by powder metallography, which can also be used to test for specific porosity.

Mixing and Blending

A good mix is a critical component of many powder-based processes. For example, metals processed into a powder form must be thoroughly mixed to prepare them for subsequent activities like compaction granulation. Failure to mix well can lead to agglomeration and segregation, which can result in poorly performing granulated products.

Most mixing operations are batch in nature. For example, a single mixer may be used to process multiple batches of ingredients in a day. Mixing systems are typically designed for a specific blend or mixture type, with blender design choices based on powder characteristics like flow properties and particle size.

For instance, shear-type mixers are effective for free-flowing powders but are not recommended for cohesive or viscous materials. For this reason, agitated and low-shear mixer designs are often chosen for blending cohesive or viscous materials. Using the right mixer can greatly reduce issues with powder degradation, heat buildup and segregation. PPS can help select the right blending equipment for your product and processing requirements. Moreover, we can also evaluate your plant and powder handling system to ensure that the blending process will work well with your existing or planned powder processing systems.

Sintering

After the green compact is formed into its final shape using a process called powder shaping, it’s time for sintering. This process takes the shaped powder and heats it to just below its melting point, which causes it to bond together without melting into a solid mass. It’s then held at that temperature for a predetermined length of time before it’s allowed to cool.

Sintering is used for a huge variety of manufacturing applications, from making spark plugs to ceramic capacitors to filling machinery shotgun shells and high-tech industrial components. There are even some materials that can’t be manufactured with any other method, such as metals with extremely high melting points like carbon, tungsten and tantalum.

There are several types of sintering processes, which all have their own advantages and disadvantages. For example, hot-press and plasma sintering help speed up the sintering process and produce denser materials than conventional methods, but they require specialized equipment. Other options include thermally activated solid state diffusion (TASSD) and reactive sintering. Linseis push rod dilatometers can be used to model these processes and optimize sintering atmospheres for both ceramics and metals.

Compaction

As part of the powder metallurgy process, compaction operations reduce the number of potential voids in the final product. In a typical system, a controlled amount of powder is fed into a precision die and compacted under pressure to create a form called a green compact. This compact has the same dimensions as the finished workpiece when ejected from the die and has sufficient strength for in-process handling and transport to a sintering furnace.

The green compacts are analyzed to determine their density and consistency. If variations in compact density exist, the resulting metal parts may exhibit shape distortion and areas of elevated stress after sintering. The compaction process can be improved with the addition of a self-diagnostic system that detects errors and alerts the operator to potential problems.

Powder metallurgy can create complex 3-dimensional shapes with close dimensional tolerances that are not possible with other metal forming processes. It is also environmentally friendly because it utilizes much less raw material than forging and metal casting. With more than 100 years of experience designing, manufacturing, and supplying mechanical powder compaction presses for use in the fabrication of powdered metal products, Gasbarre offers complete systems and worldwide support.

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