Production process of stainless steel powder for metal injection molding

 

Date：[2014/3/13]
 

Metal injection molding technology of ceramic parts by powder injection forming technology development, is a near net shape technology of a novel powder metallurgy. The main production process technology of metal injection molding are as follows: the metal powder and binder, granulating -- -- -- -- -- injection molding degreasing sintering processing -- the end product of this technology is suitable for small size production performance of large quantities of high, complex shape of powder metallurgy parts, such as the Swiss watch industry for the production of watch parts.
In recent years, the momentum of rapid development of MIM technology, including the material system can be applied: Fe-Ni alloy, stainless steel, tool steel, alloy, hard alloy, titanium alloy, nickel base superalloys, intermetallics, alumina, zirconia. Technical requirements for micron metal powder injection molding, nearly spherical shape. In addition to the powder bulk density, tap density, powder ratio of length to diameter, angle of repose, particle size distribution also have certain requirements. The main method of metal injection molding powder production technology are: water atomization method, gas atomization, carbonyl. Powder grade stainless steel metal injection used are: 304L, 316L, 317L, 410L, 430L, 434L, 440A, 440C, 17-4PH etc..
For water atomization its production process:
Selection of stainless steel raw materials -- medium frequency induction furnace melting -- composition adjustment -- deoxidizing slag -- atomization quality detection screening -- -- -- packing the main equipments used are: intermediate frequency induction furnace, high pressure pump, closed the whole milling device, circulating water pool, screening and packaging equipment, testing equipment and so on.
The atomization its production process:
Selection of stainless steel raw materials -- medium frequency induction furnace melting -- composition adjustment -- deoxidizing slag -- atomization quality detection screening -- -- -- packing the main equipments used are: intermediate frequency induction furnace, nitrogen source and atomizing device, circulating water pool, screening and packaging equipment, testing equipment and so on.
Each method has its advantages and disadvantages: water atomization method is mainly the milling process, the efficiency is high, mass production economy, can make the powder with fine, but irregular shape, which is conducive to the conformal, but the adhesive is more, affect the accuracy. In addition, the formation water and metal oxide film with high temperature reaction sintering. Gas atomization method is the main method for producing metal powder injection molding technology, the production of powder is spherical, oxidation degree is low, the binder is less, good formability, but very fine powder yield was low, prices high, conformality, and binder in C, N, H, O has an effect on sintered body. Powder purity carbonyl method produces high, stable, with very fine size, it is most suitable for MIM, but only Fe, Ni powder, can not meet the requirements of species. In order to meet the requirements for powder metal injection molding, many milling company improved the above method, also the development of the micro atomization, atomization and milling method for laminar flow. It is usually the water atomized powder and atomized powder mixed use, the former improve the tap density of the latter to maintain the conformality. Water atomized powder used at present can sinter production relative density greater than 99%, so a large part using only water atomized powder, smaller parts using atomized powder.