Re: How to Sanity Test the over-hyped BS claims made by 3D Printer vendors
FFS. You choose the method of manufacture that is most economical for the quantity of part you are producing. Injection moulding produces parts to incredible tolerances, and does so very cheaply - once you have invested in your tooling.
The major reasons one would use Additive manufacturing are:
1. Prototyping. Ten years ago, additive manufacturing was only ever referred to as 'Rapid Prototyping'.
2 Small production runs. CNC machining often sits in this space as well.
3. To produce parts that have a geometry that is difficult/impossible to manufacture by other means. Say you wanted a sponge-like shape made of aluminium - perhaps to use a catalyst substrate. You couldn't machine the inside, 'cos you couldn't get your cutting tool in there.
Your comments are akin to asking "How many components of your injection moulding machine are injection moulded?". Answer, next to sod-all. That doesn't invalidate injection moulding as a process.