How can I verify the knife material when buying a commercial meat grinder?

Get the exact steel grade, heat treatment, and measured hardness in writing rather than accepting "food-grade stainless" as an answer; also pin down the edge angle, hole size, and the spare blade's part number and price. Run your own raw material through the assembled machine and watch for sinew wrapping, temperature rise, and discharge consistency. Record those results alongside the target slice thickness, then seal the tested blade and a meat sample so any later blade or recipe change can be judged against the same benchmark.