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2 Archives of Foundry Engineering

2 2010

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The friction influence on stress in micro extrusion

100%

Piwnik J. , Mogielnicki K.

Archives of Foundry Engineering

2010

tom Vol. 10, iss. 1 spec.

451--454

Manufacturing of metallic parts by forming methods is industrially widespread due to high production rate, high accuracy, dimension’s and shape’s repeatability and good surface quality. The application of metal extrusion methods for the production of micro parts is possible, but there are some technological problems caused by small dimensions. Size effect is appearing. One of size effect symptom in micro extrusion, is a significant influence of rough contact between workpiece and tool while processing. In the case of rough contact without friction, material flows in the vicinity of the die surface. In order to explain more accurately a friction distribution in this area, the plastic wave friction model is proposed. This paper analyses specifications of a metal extrusion in micro scale. Using the friction model, a substitute friction shear factor mz and its influence on extrusion loading curves is determined in relationship to size of asperities.

Deformations in micro extrusion of metals

84%

Piwnik J. , Mogielnicki K.

Archives of Foundry Engineering

2010

tom Vol. 10, iss. 3 spec.

87--90

Production technologies of small dimensions metallic elements are known for a long time. They are produced by machining methods: turning, milling, polishing. Recently, methods for manufacturing small details by forming are developed – microforming. This process is characterized by the high dimensions accuracy and the surface smoothness of received items and the high production rate. When a forming process is scaled down to micro dimensions, the microstructure of the workpiece, the surface topology of the workpiece and that of the tooling remain unchanged. Size effect is appearing. This paper analyses specifications of a metal extrusion in micro scale. To determine the impact of the tool surface roughness on deformation process the numerical model of roughness as triangle wave were developed. In paper the influence of the wave presence on the material flow is described. Impact of the forming conditions on extrusion forces there is also characterized.