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Reasons for casting production mold damage and preventive measures

Font Size: [Big][Mid][Small] 2014-8-21    Views: 936    
One, resulting in the production of die casting causes of damage: in casting production, the most common form of mold damage is crack, crack. Stress is the main cause mold damage. Thermal, mechanical, chemical, operational impact are generated source of stress, including mechanical and thermal stresses, the stress generated in: (a) in a mold manufacturing process, rough forging quality problems. Some molds produce only a few hundred pieces to crack, and the crack has developed rapidly. There may be forged only guaranteed when the dimensions, and steel in dendrites, carbide inclusions, shrinkage, bubbles and other defects osteoporosis processing method is extended along the stretch, the formation of flow lines, which flow lines for the future the final deformation hardening, cracking, using the process of brittle fracture, failure tends to great impact. 2, cutting stress at the time of turning, milling, planing and other final processing to produce, and this stress can be eliminated by intermediate annealing. 3, produced when grinding hardened steel grinding stress, frictional heat generated during grinding, resulting in softening layer, decarbonization layer, reducing the thermal fatigue strength, easily lead to hot cracking, early cracks. After grinding for h13 steel, can be taken heated to 510-570 ℃, with one hour per 25mm thickness of insulation stress relief annealing. 4, EDM stress. Mold surface layer of rich white light collector elements and dielectric elements, hard and brittle, this layer will crack itself, there is stress. EDM should use high frequencies, so that the white layer to minimize polishing methods must be removed and tempering, tempering tempering temperature at three. (B) the mold improper heat treatment process, the mold can cause cracking and premature retirement, especially using only quenched, without quenching, and then the surface nitriding process after thousands die casting surface cracking and times will appear cracking. Quenching the steel to produce stress is the result of thermal stresses during cooling phase change of the tissue superimposed stress, the stress is caused by the deformation hardening, cracking reason, the solid must be tempered to eliminate stress. (C) In the production process of a casting mold temperature in pre-production mold should be preheated to a certain temperature, otherwise the chilled liquid metal filling when the high temperature, the inner and outer layers result in mold temperature gradient increases, the formation of thermal stress, so mold surface cracking, even cracking. In the production process, the mold temperature rising, when the mold temperature overheating prone stick mode, the motion caused by failure of the mold part surface damage. Cooling temperature control system should be set up to keep the mold operating temperature within a certain range.
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