Miniaturized tube fixed plug drawing: Determination of the friction coefficients and drawing limit of 316 LVM stainless steel

Tube drawing with a fixed plug is investigated experimentally and numerically in order to optimise an industrial pass sequence. Tube drawings are performed on a laboratory drawing bench equipped with force, displacement and temperature sensors. The drawing limit of 316 LVM stainless steel (SS) tubes is determined by varying the plug position and the effect of lubricant is discussed. The numerical model relies on the precise die geometry measured using a contact method and on the mechanical behaviour of SS 316 LVM characterised by tensile tests between 20 °C and 200 °C on annealed tubes. The friction coefficients between tube and die and tube and plug are determined by FE modelling by comparing measured and simulated plug, die and drawing forces. The use of a solid lubricant together with the lubricating oil prevents stick and slip and lowers the friction coefficients. Friction is further decreased by preheating the die. The identified friction coefficients are discussed in terms of the classic Stribeck friction curves and lubrication is found to be in the hydrodynamic regime.