Tool acceptability isn't a 'standard' decision. Let's imagine the unthinkable occurs, and an accident takes place that involves a product you manufacture. Your company becomes the target of legal action, and before you know it, a plaintiff's lawyer has subpoenaed your quality records, including those relating to the instruments and gages used to verify the product.
CMM capabilities can be expanded with additional tools.
In a perfect world, or in a fully integrated manufacturing environment, metrology systems would be able to measure all necessary parameters in one pass, without error, and feed back results seamlessly to computer-integrated manufacturing networks, in the formats most useful for machine control and process management.
Prior to the introduction of automated image-analysis systems, lab operators often had to rely on expensive film-based methods of documenting and analyzing images.