Analyses and experiments of hydro-drawing of stainless steel microtubes

Cold drawing is commonly employed to manufacture metallic rods and tubes for achieving grain refinement and enhancing material strengths. However, in conventional cold drawing of micro-tubes, it is difficult to insert plugs or mandrels into the tube to control the thickness of the drawn tube. Hydro-drawing is an alternative effective compound-forming method. This study investigates the deformation behavior of SUS304 microtubes during hydro-drawing using the finite element analysis. A microtube with an initial outer diameter of 2.0[Formula: see text]mm and a wall thickness of 0.15[Formula: see text]mm is reduced to 1.0[Formula: see text]mm in diameter through three drawing passes. Drawing experiments are carried out using a newly developed hydro-drawing machine. Hydraulic oil is injected into the tube to prevent wall thickening. Heat treatment is applied to reduce the hardness of the tube to achieve lower drawing stress and less wall thickening. Experimental results are compared with finite element simulation results to validate the numerical model.