[TheForge] investment casting

[northwoods]

I would like to have multiple copies of certain items reproduced through
investment casting. I have located a business which will cast what I need if
I supply the wax patterns. I can handle making the master patterns and the
silicone molds but have questions regarding casting the wax patterns. What I
am wondering is do I need a wax injection machine to inject the wax and have
it bubble free, or can I get away without one and just pour the wax? I can't
seem to find any web sites that give info on the process  I need which is to
make silicone molds so I can produce wax patterns to reproduce multiple
items, and not make a wax pattern and mold to cast one item like jewelry
makers often do

Thanks for any info,
T. Clark.