MIM Material Selection

[tfrap]

We are looking at Metal Injection Molding to replace a high volume complex machined part. The material currently being used is C-1117 that is carbonitrided to Rc 56-60, .009 to .010 in. deep. Using MIM we are considering 4140 or 4340 that would be fully hardened and stress relieved or tempered back to the Rc 56-60 range. Because of powder availability for MIM Carbonyl Iron has also been suggested and would require carbonitriding to produce the desired surface hardness. Any thoughts?

 

[TVP]

The maximum hardness that you can achieve with 0.40 C is 60 HRC, so you won't be doing much tempering if you want to stay in the 56-60 HRC range. Depending on the loading conditions and environment, you may want to stick with a surface hardening process like carbonitriding.

 

[metalpart]

There are a lot of other things to be taken into account beside hardness when choosing right material for MIM parts, such as maximum cross section, weight of part(raw material costs), tolerances to be met, type of mechanical stress to be applied, need of additional machining after sintering....
If you provide more information on general features of the part dimensions, weight, application) we could advise more detailed

metalpart

 

[Tuptus]

Have you considered traditional P/M?
Range of materials is much wider and though there are shape limitations very oftem they could be worked out in design stage and it is much cheaper.