Critical vs Non-Critical Dimensioning
Critical vs Non-Critical Dimensioning
(OP)
Hey guys,
I am new here and I joined specifically to ask this question.
What is the standard for putting dimensions on a print? I am currently making prints for FAB parts and I dimension everything that would be needed to make a part. Here is an easy example: 1/4" thick bar that is a 2" x 4" rectangle with 1/2" radius on all four corners. So the main part of the print would indicate the part is 1/4" thick x 2" wide x 4" long and then have a 1/2" TYP. pointed to the corner radius.
Here is where the question comes in: Our new Quality Manager that was hired says we have to remove all dimensions he can't measure. He can't measure the radius on the corners so that dimension needs to be removed from the print. The 1/2" radius is not critical to the part but having a radius (instead of a point) is critical. So the critical part is just the overall dimensions (1/4" thick, 2" x 4"). What would be the correct method of noting something like this? Should I remove the radius dimension completely, like QA wants? Or can I indicate what is critical and needs to be checked, leaving the non-critical dimension as-is? What is the standard?
I use Solidworks 2012 for modeling and prints. If this is in the wrong area, please let me know. Thanks.
I am new here and I joined specifically to ask this question.
What is the standard for putting dimensions on a print? I am currently making prints for FAB parts and I dimension everything that would be needed to make a part. Here is an easy example: 1/4" thick bar that is a 2" x 4" rectangle with 1/2" radius on all four corners. So the main part of the print would indicate the part is 1/4" thick x 2" wide x 4" long and then have a 1/2" TYP. pointed to the corner radius.
Here is where the question comes in: Our new Quality Manager that was hired says we have to remove all dimensions he can't measure. He can't measure the radius on the corners so that dimension needs to be removed from the print. The 1/2" radius is not critical to the part but having a radius (instead of a point) is critical. So the critical part is just the overall dimensions (1/4" thick, 2" x 4"). What would be the correct method of noting something like this? Should I remove the radius dimension completely, like QA wants? Or can I indicate what is critical and needs to be checked, leaving the non-critical dimension as-is? What is the standard?
I use Solidworks 2012 for modeling and prints. If this is in the wrong area, please let me know. Thanks.






RE: Critical vs Non-Critical Dimensioning
A radius should be specified, otherwise you would have no recourse if either no radius was machined, nor if one was machined too large.
RE: Critical vs Non-Critical Dimensioning
1. The SW fix is to add an "Inspection Dimension" border around important dimensions. It is a button above the dimension text box, and can be found in 'dimension value property manager' portion of the Help section. The significance of this border may vary company to company, so quality needs to make sure they define a process for the symbol.
2. Make non-important Reference by adding () around the dimension. There is a button for it as well, located in the same place as the inspection dimension. Again Quality needs to define what "reference" means.
3. Do as your manager says
The most important thing is documentation of meanings of dimension symbols. will the critical dimensions be used for 1st article, 10pc incoming inspection, 100% inspection, etc? Same with regular dimensions without any symbols (like you have now); will anyone ever verify these dimensions, maybe only on 1st article inspection? Does a refererence dimension never get checked, if so why is it on the print?
These are just some of the questions you have to ask yourself when adding different 'levels' of dimensioning. I worked for a company that implemented 4 levels of inspection dimensions, regular dimensions, and reference dimensions...all with different meanings
RE: Critical vs Non-Critical Dimensioning
Your drawings have several "customers" or users. Each one has their own priorities. He is only one user among many.
Seriously though, if this isn't just a "turf war" thing with him, work with him to address his needs. All he's really asking is "which features do I need to verify and which ones can I ignore?" I'm sure you can work out some system that would identify those for him. Circles, squares, ovals, colors, etc. Maybe if the radius isn't important you can just replace the dimension with a note to remove sharp corners.
Does this mean that when he acquires new measurement tools that give him more capabilities, you need to go back thru all your drawings and add the "omitted" dimensions back? Hmm...
RE: Critical vs Non-Critical Dimensioning
-Dustin
Professional Engineer
Pretty good with SolidWorks
RE: Critical vs Non-Critical Dimensioning
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Critical vs Non-Critical Dimensioning
Regards,
Scott Baugh, CSWP
FAQ731-376: Eng-Tips.com Forum PoliciesBerry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader
www.scottjbaugh.com
RE: Critical vs Non-Critical Dimensioning
Alternately, how about a chamfer? Easier to measure, and (depending on your fabrication method) possibly easier to machine.
-handleman, CSWP (The new, easy test)
RE: Critical vs Non-Critical Dimensioning
RE: Critical vs Non-Critical Dimensioning
RE: Critical vs Non-Critical Dimensioning
Scott Baugh, CSWP
FAQ731-376: Eng-Tips.com Forum PoliciesBerry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader
www.scottjbaugh.com