How many Ω should the ground resistance of PCBA-related equipment be controlled?

Dear experts, I would like to ask: The equipment that produces PCBA products (such as printing presses, SMT machines, reflux furnaces, AOI, wave soldering furnaces, etc.), their grounding resistance should be controlled within how many Ω? Is there a standard basis or explanation?

There is a standard practice, SP10.1 that may help with machines. It describes several methods on how to evaluate equipment. This is an old standard practice and will be incorporated into SP17.1 or a new standard practice 17.X. It is recommended that all metal parts in the machine that comes into contact with ESDS items be grounded at 1 ohm or less but it is not a requirement of any standard.

I typically aim for <1E9 ohms max, specially if it is a worksurface. Additionally, I try to limit the surface resistance whenever possible from 1E6 to 1E8 ohms to prevent critical contacts. I recommend reviewing SP17.1 sections 6 and 7 to help you with non-standard evaluations.