NEEDLE FOR DOT PRINTER

PURPOSE:To enhance the anti-wear property and impact resistance of a needle, by applying solution heat-treatment to a marageing steel wire material obtained by containing an age-hardening element such as Ti or Al in an alloy comprising a specific amount of Ni, Co, Mo and Fe. CONSTITUTION:An age hardening element such as titanium or aluminum is contained in an alloy consisting of 10-20% of nickel, 8-20% of cobalt, 5-15% of molybdenum and the remainder of iron to prepare a marageing steel wire material. This steel wire material is subjected to solution heat-treatment at 800- 850 deg.C and the treated material is drawn into a fine wire by cold processing while twist correcting processing is applied to the fine wire to impact true linearity thereto and ageing treatment is further applied thereto to obtain a needle for a dot printer formed of a wire material having Vickers hardness of HV800 or more. The aforementioned correcting processing is performed, for example, by twisting a wire material with a length of 300mm. and a diameter of 0.3mm. 25 times from one end thereof in such a state that both ends thereof are fixedly held.