One comment I’ve seen about ASME suggests that it is geared towards fully detailing product definition. One trap that rookie designers and engineers will often fall into is over-specifying their parts by placing manufacturing process information on the drawing.
The new designer may do this because maybe a machine shop made the part wrong and was trying to work the rookie’s inexperience to weasel out of their responsibility. Maybe someone in Quality Control was confused by a drawing because they don’t have adequate blueprint reading skills, so they come to the new designer to ask that more information be spelled out on the drawing (when it is already fully specified). These are just a couple of examples. Often, new designers don’t know why manufacturing processes are not included on drawings, nor even that there exists standards that forbid it.
ASME Y14.5-2009 (and previous versions) states:
1.4(d)The drawing should define a part without specifying manufacturing methods. …However, in those instances where manufacturing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing.
It is usually pretty obvious when manufacturing methods are necessary to the engineering requirements, even to the individuals new to the field. Unless one is in particular industries, manufacturing methods are almost never required. A drawing should fully detail the final product without over specification.
ASME Y14.5-2009 adds as an example:
Thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched, or made by any other operation.
The manufacturer is responsible to provide a final product that complies with the drawing regardless to the processes they use. It is still important for designers to know the processes that will most likely be employed, so they know that the product is economically manufacturable. This does not mean that they should unnecessarily limit the manufacturer to particular processes.