Die-casting method using sintered material and a die-cast product manufactured thereby

Abstract

A die-casting method using a sintered material increases bonding strength between an insert and a casting portion. A die-cast product is manufactured using the die-casting method. The die-casting method includes an insert preparation step of preparing an insert having pores formed in a surface thereof by compacting iron-based powder and then sintering the compacted iron-based powder. The pores have a size of 100 μm or more and are distributed over the surface of the insert and the insert has a density of 6.4 to 6.9 g/cm 3 The method includes a die-casting step of placing the prepared insert inside a mold and injecting molten aluminum into the mold so as to perform casting while causing the molten aluminum to infiltrate into the pores formed in the surface of the insert.

What is claimed is: 
     
         1 . A die-casting method using a sintered material, the die-casting method comprising:
 an insert preparation step of preparing an insert having pores formed in a surface thereof by compacting iron-based powder and then sintering the compacted iron-based powder, wherein the pores have a size of 100 μm or more and are distributed over the surface of the insert and the insert has a density of 6.4 to 6.9 g/cm 3 ; and   a die-casting step of placing the prepared insert inside a mold and injecting molten aluminum into the mold so as to perform casting while causing the molten aluminum to infiltrate into the pores formed in the surface of the insert.   
     
     
         2 . The die-casting method of  claim 1 , further comprising, before the die-casting step,
 an insert-preheating step of preheating the insert prepared in the insert preparation step to a temperature of 300 to 450° C.   
     
     
         3 . The die-casting method of  claim 1 , further comprising, before the die-casting step,
 a molten aluminum preparation step of preparing the molten aluminum at a temperature of 600 to 750° C., and   a mold-preheating step of preheating the mold to a temperature of 200 to 250° C.   
     
     
         4 . The die-casting method of  claim 1 , wherein, in the die-casting step,
 a casting pressure is 600 to 1000 cm 3 ,   a gate speed is 40 to 60 m/sec,   an injection time is 0.05 to 0.15 sec, and   an injection rate is divided into a first section and a second section, wherein the injection rate in the first section is 0.5 to 1.5 m/sec, and the injection rate in the second section is 2 to 3 m/sec.   
     
     
         5 . A die-cast product comprising:
 an insert having pores formed in a surface thereof, the insert being formed of compacted and sintered iron-based powder; and   a casting portion of die-cast molten aluminum around the insert,   wherein the molten aluminum has infiltrated into the pores to a predetermined depth so as to form a bonding portion on the surface of the insert.   
     
     
         6 . The die-cast product of  claim 5 , wherein an area other than the bonding portion in the insert has a density of 6.4 to 6.9 g/cm 3 , and
 the bonding portion in the insert has a density of 6.7 to 7.1 g/cm 3 , a tensile strength of 400 MPa or more, and a hardness of HRB 70 or more.   
     
     
         7 . The die-cast product of  claim 5 , wherein a bonding strength between the insert and the casting portion is 100 MPa or more. 
     
     
         8 . The die-cast product of  claim 5 , wherein the die-cast product is a component of an internal combustion engine.