The injection mold can simple divide into mold frame and cavity two components.
The mold frame of metal injection is completely same with plastic injection,the material of mold frame can refer to plastic injection mold to choose: usually, dynamic template, fixed mold, push plate can be 45 steel, its hardness is 180"250HBS. The
other plate material can use 45 steel or Q235 steel. For mold frame with very high precision, all of plate materials are use 45 steel, even if use Cr12 mini deformation mold steel, quench treatment.Guide column, guide sleeve can use T8A quench to
50''55HRC or 20 steel carburize 0.5''0.8mm thickness, quenched to 56''60HRC.
When injection mold is work, it usually need undertake 20''50MPa alternating load, and accompanied by alternating hot and cold temperature at the same time. In Ultra precision injection molding,the forming pressure used can even exceed
several times the normal service pressure. And its working life of injection mold usually have 150 thousand to 200 thousand times, thus, the mold should have enough strength and rigidity.
The cavity of metal injection mold is usually manufactured by 58''62HRC quenching, thus, it must be note its stress concentrations caused by sharp corners, grooved country, incisions and machining defects. Its defects will great decrease fatigue
strength of mold.
For cavity components, the material should consider wear resistance, quench shape stability, corrosion resistance and processing properties.Because metal injection material on the erosion of the mold is much more serious than the average
plastic,the wear resistance is the basic requests of using mass production metal injection mold cavity, it requested that the hardness of cavity is 58''62HRC.Because tool steel have a combination of strength, hardness, toughness, hardenability,
corrosion resistance and processing properties, is the cavity of choice for materials. The common material have ally mold steel,such as Cr12、Cr12MoV、Cr12MoV、Cr2Mn2SiWMoV、Cr6WV and high-speed steel W18CrV、W6Mo5Cr4V2 and so on.
The structure of injection mold is complex, usually use high-precision EDM, wire cutting etc.In injection temperature, the metal injection material will produce corrosive gas, it is a request for mold material.
In special case, such as samples or trial orders, in order to simplify process, Q235 steel, 45 steel.Alumium ally, Zn-Ni ally etc, it can used to manufacture some cavity,and it will great shorten development cycle of samples, but this molds are not used
by mass production.
In total, when we choose which mold, it should consider the quantities of parts, structure of parts,precision, machining process and technology, its complexity of heat treatment and material resources and so on respects.
