Since there are always all kinds of factors that cannot be completely controlled in the process of production, manufacturing specifications would allow certain tolerance on dimensions, or allow a small amount of subpar products, which is in fact an acknowledgement of the randomness of the production process.
Since there are always all kinds of factors that cannot be completely controlled in the process of production, manufacturing specifications would allow certain tolerance on dimensions, or allow a small amount of products to be subpar, which is in fact an acknowledgement of the randomness of the production process.