What metals are we talking about? What is the weight range of the castings?

For Aluminum alloy (and zinc thought that's probably not relevant) you could consider rubber plaster molding (also goes by variations on that name) such as I've got before from these folks: http://aljcast.com/

Have you considered 3D printing of moulds and cores?

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

Making SLS wax masters is one proven option, as is the SLA hollow plastic master process.

Proud Member of the Reality-Based Community..

To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?

arunmrao, Ennomotive is looking for alternative Investment Casting processes, not sand-casting options.

Proud Member of the Reality-Based Community..

To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?

Lost wax casting is also called investment casting. One possible alternative is lost foam casting, also called evaporative pattern casting. Here are some links for more information:

http://www.brp-castings.com/

http://www.generalaluminum.com/capabilities-lost-f...

http://www.e-smarrt.org/FinalReports/Task3_8_MfgAd...

https://www.mercalloy.com/mercury-castings/

http://www.americanfoamcast.com/lostFoam.asp

http://www.foamcast.in/uploads/4/5/2/1/4521329/foa...

Impact extrusion or forging

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

Some parts there is no substitution of any casting process except lost wax. An example is hot section turbine blades. Air foil shape tolerances and smooth surfaces and extremely complex and tight tolerance cores and super alloy materials requiring vacuum melt and pour. There is no substitute.

Part tolerance is one of the major reasons to use investment castings. You will have to machine more details if the tolerances are tight.

Lost foam casting is investment casting except the investment part is foam part.

Look at your parts being cast using lost wax and review part tolerances and features. Permanent mold casting or die casting are possibilities if the volumes are high enough and the materails are strong enough.

Machine the part from solid is the complexity is not great.

Good Luck

Thanks a lot KENAT, arunmrao, capnhook, TVP, ornerynorsk and BillPSU
for putting so much thought in it, and sharing your knowledge!