critical dimensions
critical dimensions
(OP)
Critical dimensions on drawings have become an issue at my company and my question is: Is there a standard symbol or method of indicating specific dimensions on a drawing are critical to the design form, fit or function of a part to the supplier as well as incomming inspection?





RE: critical dimensions
They usta do this on some GE drawings.
RE: critical dimensions
RE: critical dimensions
Also, some CAD packages have built-in options that are used during 2D drawing creation to identify dimensions that needs to be inspected to. I know SolidWorks makes the option available to create a oblong bubble around dimensions that are for inspection use only. you could use something like this in conjuction with a note on your drawings to identify critical dims.
"The attempt and not the deed confounds us."
RE: critical dimensions
Each company chooses it's own marking for critical dimensions.
E.g. a triangle, or a romboid with a C inside and a legend where its meaning is clearly stated: Dimensions with this marking are critical.
Also, indicating tolerances is pretty much indicative of criticality.
E.g. stating 2.000in +/- 0.050in
is totally different from
2.000 in +0.000in/-0.003in
This will be understood by any decent millwright.
HTH
Saludos.
a.
RE: critical dimensions
Choose any marking you want to mark a critical dimension. Then, in the general notes, define that symbol. For example, we use a triangle with a solid square in the middle. In the general notes, we say "Where applied, dimensions marked symbol shall be validated for functional use."
RE: critical dimensions
If a dimension is critical it should be toleranced as so. One such method of doing this above that of general tolerancing is geometric tolerancing.
Take a look through BS308 if you require further information.
What it sound like you are trying to do is create your own method of identifying important dimensions which manufacturers are failing to meet.
Attack the root cause of the problem - are your designs incorrect (if so correct them) or are your manufacturers failing to manufacture corretly (if so either find another manufacturer or get them to sort the problem out).
GB (UK)
RE: critical dimensions
RE: critical dimensions
We too have this system working in our factory. The way we indicate critical dimensions is to surround the dimension with a rectangle, but instead of a flat line at each end we have semicircles, sort of pill shaped. In the note section we indicate that all dim. marked with ???? is a critical dimension etc etc etc..
Hope this helps you.