Analysis of methods to improve service life of molds (3)

Reasonable formulation of forging specifications for die steel

Mold materials for making home appliance plastic parts are mostly high-carbon, high-alloy steels, and there are defects such as composition segregation, tissue segregation, and carbide segregation exist in varying degrees, which cannot be directly used for molding. At the same time, shape and size of raw materials used are difficult to match with module, forging is an indispensable means of obtaining required internal organization and performance, reducing amount of machining. Through forging can effectively improve carbide segregation of tool steel, and generally can reduce carbide segregation level 2 after forging, up to level 3.
Die steel generally has poor thermal conductivity, and heating speed must be slow and uniform. Large forgings generally use preheating or step heating to control heating speed. Position of steel in furnace should be appropriate, and sometimes it should be repeatedly turned over so as to make heat as uniform as possible. In order to maximize breaking and uniform carbide, it is necessary to adopt a deformation process in which pier is thick, long and repeated repeatedly, and finally, like kneading dough, it is turned up and down, front and back, left and right, so that internal deformation is sufficient and uniform. After billet is forged, it should be slowly cooled with furnace or cooled in a hot ash box. However, for Cr12 steel, if it is slowly cooled after forging, it is easy to precipitate network carbide on grain boundary, thus affecting quality of blank. Therefore, it should be quickly cooled to about 700℃, then pit cold or into furnace slow cooling. Forgings should minimize number of forging fires to control oxidation and decarburization of billet.

Select a reasonable mold heat treatment process

There are many ways to improve performance of mold to produce excellent medical products plastic parts. Use of new heat treatment technology is a cost-effective and effective way. Mold heat treatment process mainly includes matrix strengthening and surface strengthening treatment; strengthening and toughening of matrix is to strengthen toughness and strength of matrix, reduce occurrence of fracture and deformation. Surface strengthening is mainly to increase wear resistance, corrosion resistance and lubrication properties of surface.

(source:https://www.hthc-tech.com/analysis-of-methods-to-improve-service-life-of-molds-3/)