Powder Compacting Equipment Information
Powder compacting equipment shapes powders as part of a forming process as well as to compress a wide range of materials into compact shapes for transportation and ease of handling. Compaction is done for a variety of reasons, including:
To produce uniform blends or mixtures
To produce a uniform particle size range
To control dust
To adjust flow properties
To control bulk density
To control particle hardness
To improve solution or dispersion rates
Although there are several configurations of powder compactors, listed below, the basic concept is to force fine powders between two counter rotating rollers. As the powder flows through the region of maximum pressure, the material is formed into a solid compact or sheet.
There are seven main configurations of powder compacting equipment (although custom varieties are available). These types are defined either by the shape of the product they produce or the technology used to process materials.
When selecting a powder compactor it is important to consider the volume of material that will need to be compacted. The greater the downward force, the larger the volume of material that can be compacted. This efficiency is a function of its feed system and the method by which downward force is generated.
The diameter/width capacity describes the maximum internal diameter of the die cavity that can be used in tableting presses. For isostatic presses, the internal diameter of the chamber determines the diameter or width capacity. For briquetting presses, the roll diameter is stated here, since the cavity can vary dynamically. Depth/fill capacity is the maximum internal length of the die cavity that can be used in the uniaxial or tableting press. For isostatic presses, the internal length of the chamber determines the diameter or width capacity. On briquetting presses, the spacing range of rolls determines the thickness range of compacted sheet.
Other specifications to consider include the maximum operating force, which describes the force required to reach the desired density during part production, and maximum operating pressure, which also describes the force required to reach desired density but varies with material and part geometry.
If the powder compactor will be used in a high-volume production facility the bulk production rate should be noted depending on the number of kilograms per hour that can be processed through the equipment.
Materials compressed by powder compacting equipment include powdered metals, ceramics, carbides, composites, pharmaceuticals, carbon/graphite, ferrites, explosives, chemicals, foods, nuclear fuel, or other materials. Metal or ceramic powder compacts require additional processing such as sintering or forging to provide a finished part.
Materials with a low bulk density tend to hold air entrained internally and thus will resist the precompression that is required in order to pass through the rolls.
Self-diagnostic systems provide continuous monitoring of the progress and functionality of the compaction process. If an error occurs, the operator will receive a warning, the machine will stop at the end of the current cycle, or the machine will be stopped immediately. Errors can be recorded for later investigation.
Communications/remote control allows the powder compaction equipment to be supplied with a networking capability such as Ethernet for monitoring and operation from a remote location or central control station. This feature might include a camera for visual monitoring of the process.
A robotic interface allows the press to be integrated with a robot for automated loading of powder media or extraction of finished parts.
A vacuum can be added to the system when compaction is made difficult by a material with a low bulk density. Vacuums can increase capacity of a powder compactor.
Automation allows for process control and data monitoring.
Powder compactors must adhere to several standards, including ANSI B11.16 to ensure proper design and functionality. BS EN ISO 4492 is used for the determination of dimensional changes associated with compacting and sintering for metallic powders.