Spheroidization/lubrication

Powder preparation for pressing consists of four phases homogenization blending precompaction and granulation and spheroidization and lubrication. 

Spheroidization and lubrication—In the first step, the entire bicone is tumbled to spheroidize the powder granules through abrasion and the adhesion of fine powder particles, further improving the powder flow behavior. In some processes, a lubricant is also added to enhance the flowability of the powder during future handling steps. 

Reducing particle interaction by spheroidization, an increase in the average size, or the addition of lubricants such as poly(vinyl alcohol) (PVA) or poly(ethylene glycol) (PEG). 

The housing elements, rotor, and stator are of spheroidal graphite iron or of material that is resistant to cavitation and corrosion. The shaft is of high-quality, heat-treatable steel and the shaft extensions are normally finished to DIN standards although other arrangements are possible. Oil is used as a lubricant for the bearings and radial-lip-type shaft seals or labyrinth seals are normally fitted. Mechanical end-face seals can be provided. 

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