SURFACE TREATMENT METHOD FOR PLASTIC INJECTION MOLD USING PLASMA ION NITRIDING FOR OBTAINING SURFACES WITH HIGH HARDNESS BY FORMING MARTENSITE LAYER THROUGH LASER HEAT TREATMENT AND BY ION NITRIDING

摘要

PURPOSE: A surface treatment method for plastic injection mold using plasma ion nitriding is provided to treat surfaces of large plastic injection mold to have high hardness and high wear and fatigue resistance by a laser heat treatment and ion nitriding.;CONSTITUTION: A surface treatment method for plastic injection mold using plasma comprise a laser heat treatment step of treating surfaces of a plastic injection mold with laser heating source; a glow discharge step of activating the surface of plastic injection mold through a glow discharge treatment at nitrogen and hydrogen atmosphere by providing nitrogen and hydrogen into a vacuumized nitrate brazier; and a plasma ion nitriding step of putting the surface of plastic injection mold into the nitrate brazier for plasma ion nitriding. At the plasma heat treatment step, the ion nitriding is preformed in temperature of 470 deg. C, pressure of 200Pa, voltage of 650V, pulse ratio of 0.3 for 20 hours. At the laser heat treatment step, the ion nitriding is preformed in temperature of 950-1100 deg. C, and the heat treatment speed range of 2-6mm/sec. At the glow discharge step, the glow discharge is performed under the condition such that the ratio of nitrogen to hydrogen is 8 to 2, the pressure of the inside of the nitrate brazier is 70Pa, and the temperature is 350-500 deg. C.;COPYRIGHT KIPO 2013;[Reference numerals] (AA) Step of confirming configuration data; (BB) Step of setting a laser heat treatment condition; (CC) Step of laser heat treatment; (DD) Step of post-processing in laser heat treatment; (EE) Step of cleaning a surface; (FF) Step of glow discharge; (GG) Step of plasma ion-nitriding; (HH) Step of modifying surface profile