Mass, with correct units, in Parts List 1

[potrero]

I know that this has been discussed before in several threads (such as thread561-199292), but I still am having difficulty getting the mass of a component to display correctly in the Parts List of a drawing.

I'd like to be able to use the $MASS attribute available when using the weight in Part->File->Properties->Weight (Update on Save). Following the conventional approach of assigning the attribute <W$=@$MASS> to a column in the Parts List, the result shows up in units of grams, not kg.

I've tried recommendations I've seen in other postings such as:

<W$=@$MASS/1000> which results in a blank (nothing displayed, even after I update the list)

and

<W$=@$MASS>/1000 which results in a strange string composed of the part mass in grams concatenated with what looks to be some form of a part ID and the text "/100".

I've also tried:

<W$=(@$MASS/1000)>
and
<W$=@($MASS/1000)>
and
<W$=@$(MASS/1000)>
all of which result in blank output.

So, any suggestions? Thank you.

 

[JohnRBaker]

What version of NX are you running?

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[potrero]

NX5.0.4

 

[potrero]

I'll try to write a more complete answer but for now, here's what I've found:

I don't know why the $MASS attribute comes into the drawing in grams even though the part is in KG, but that's the way it is. In order to have the Parts List show mass in KG, I had to do a couple of things:

After selecting the appropriate column in the Parts List, Edit Style and enable the interpretation of the cells "as formula". Then you can go back and enter
<W$=@$MASS>/1000
and the cells will calculate and display correctly. One also needs to set the decimal places to what is desired.

I learned a couple other useful things:

* To change the text size of the Parts List cells (ie: not just the header row, but all the cells) one selects each column and changes the text height to the desired value.

* For some reason, if you insert a row above/below the header, and you want to subsequently want to remove that row (which is now part of the header, not part of the parts list body), it seems that "delete" and "cut" don't do the job. To remove the extra row, I had to individually select each columnar pair in the header and do a "merge cells". Not sure if this is by design or not but the workaround seems work fine.

 

[JohnRBaker]

Attached is an example of another approach that you can use with NX 5 models. Open the 'Housing.prt' file and go to the Expression system and note the expressions for MASS and WEIGHT_Attribute. Then go to File -> Properties and note the Part Attribute for WEIGHT. Any change in the model will cause this attribute to update accordingly. Also note that using the expression system you can control what units this value is being recorded in.

Now open the drawing and note the Parts List column for WEIGHT. The value shown there is in Kg.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[potrero]

John,
Thanks for the example files and the description. Is the approach you demonstrated here considered to be the "best practice" method for handling weight in the parts list?

 

[JohnRBaker]

At the moment, yes. However, there is a project being worked on for NX 7 which will replace the underlying architecture for Attributes and as a result of that project we will be getting some additional tools for linking expressions and attributes which will make tasks such as adding the weight of a component to the Parts List a bit more direct and easy to accomplish, but for now this is probably the best and most efficient approach. BTW, my master modeling templates have these expressions and attributes predefined so that all I have to do after my model is complete is to added the Measurement expressions and copy the 'p' number for the MASS (MASS when working in Metric units or WEIGHT if in Imperial units) into the MASS expression and I'm done.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[potrero]

John,
For assemblies, then, do you select all assembly bodies in the associative Body Measurement? This measurement would then need to be manually updated if new components were added to the assembly, right?

 

[JohnRBaker]

Assemblies are a little trickier and more work needs to be done in other areas before reliable (in terms of keeping up with the changes to the assembly itself) mass property data can be captured for use as an attribute.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[cmacca]

This seems to be quiet a good method of getting the weight of a part to show up in a parts list when using master model. I did notice though that the weight didn't change after adding a hole to your example, I then realised that the body measurement in the part navigator (timestamp order on) needs to be at the end of the tree. I've read that NX6 does not have a feature tree as such, so will the body measurement always update after adding features without having to reorder? On the subject of NX6, how does it handle comands and functions that use the timestamp order ie fix at current timestamp.

nx5.0.4.1

 

[Xwheelguy]

cmacca,

NX6 gives you the OPTION of having a feature tree or no feature tree.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[velto]

John
Why when I used your example and did a hole on it, the weight did not update?

 

[potrero]

@velto - do you mean it didn't update on the drawing? Check to see if you updated the drawing sheet (right click on the Sheet>Update).

I noticed on a different part, using this "Measure Body" technique suggested by John, that the mass on the drawing sheet didn't auto-update until I manually updated the Sheet.

 

[JohnRBaker]

Make sure that the 'measure feature' came AFTER the 'hole feature' (you will probably have to move one or the other to make sure that the measure remains at the END/BOTTOM of the tree).

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[potrero]

John - could there be an option to have the Measure Body feature ALWAYS be at the bottom of the tree?

Could go a long way towards preventing simple screw-ups (since the INTENT of using the feature in this way is to always report the final mass...)

 

[JohnRBaker]

It's on our 'to do' list.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[potrero]

Great!

 

[moog2]

John,
In your example, housing.prt, is there a way you can round down the weight to display to only 1 or 2 decimal places ??

 

[JohnRBaker]

No, that's an issue that we just discussed the other day while we were going over the 'features' that we need in the new Attribute sub-system that we hope to have implemented for NX 7. At the moment there are no real formating tools, particularly when to comes to Part Attributes, but it's high on our list for the new project.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.