316L Stainless Steel Powder Injection Molding Process

This paper studies the316L stainless steel powder which particle size D90is8.9um, D50is21.5um, D10is34um injection molding process. The binder is plastic system which is baseon paraffin, the polyethylene compoment in three groups of binders are20%,30%,40%.Powderparticle size distribution;binder compatibility;forming process;mixing process;degreasingprocess;the sintering process.were studied the results shows as follow:The content of60%of the powder loading is suitable for the precess.The higher contentof Polyethylene (HDPE) in the binder the lowerr flow rate of the feedstock;it has good fluiditywhen content of HDPE is20%and30%, little difference between the two, separation betweenpowder and binder is easy to happen; The fluidity decreased obviously when the content ofHDPE reached40%,separation between powder and binder is not easy to happen.There is little difference of the thermal properities between three binders. Similar thermaldebinding process could be adopted, the strength of the green parts is too low to resistdeformation, cracking durning thermal debing when the content of HDPE is20%and30%.Green parts without any defect can be got when the content of HDPE is40%after thermaldebinding.Defects produced by direct thermal debinding can be avoided effectively by Solventdegreasing+thermal debinding process.Most of the binder can be removed when the greenparts soak in the N-heptane at45℃for7h，then heat to350℃at the heating rate of2℃/min，keep the temperature of1h，then heat to550℃at the heating rate of1℃/min.Residual carcon in the green parts must be romove before stintering. Otherwise thesintering densification process would be impeded. Sintering temperature of1350℃andthen keep the temperature for1h is appropriate stinstering process.