The paper presents selected results of KOBO extrusion process of circular profile ϕ10 mm from aluminum alloy 2099. The main aim of the performed research was to determine the influence of the oscillation frequency of a die on the magnitude of extrusion force. During the process such parameters, as extrusion force, rate of stem and frequency of die oscillation were recorded; oscillating angle of a die was constant and equal ±8°. The die oscillation frequency was changeable in performed tests in the range of 2 ÷ 7 Hz. The obtained results allowed to determine the relation between the maximum extrusion force and the die oscillation frequency during extrusion of aluminum 2099 alloy.

The paper focuses on the experimental analysis of mechanical characteristics of the KOBO process. Basing on the recorded force versus stem position, three stages of KOBO extrusion process were determined, i.e. initialization, stabilization and uniform extrusion. Points separating these stages are two inflection points of recorded diagram. The analysis of each stage was made basing on the results of force diagrams and literature data.