Incorrect mass (density) for assembly

[Anonymous]

Hello, 

I have an assembly with incorrect mass (density).It is abnormaly big. and the individual parts have correct mass (density). It is a weldment type. Can you please identify what causes this error? 

Thank you 

Tibor 

[mdavis22569]

I have a total on my mass as 228 kg. ..which is what I got when I added them up piece by piece

C003 is 85kg

C004 is 28kg

I did go to the manage tab and hit update mass though

[Anonymous]

I attach my I properties. Density for the assembly is totally incorrect (and density for individual parts is correct for mild steel) I dont know where the problem is. 

[mdavis22569]

Try refreshing the Mass, I did it on 14

Are you up to date on Updates/patches etc for Inventor?

 

[Anonymous]

Yes, I have the latest Update 5 for Inventor 2014. It is strange that we get two different i-properties for the same model. If I create a substitute for the same assembly, than I get the correct mass. 

[mdavis22569]

I don't have 2014 at work ... However make sure you don't have any overrides in the Material Library and they are all mark "as material" so the assembly isn't something different.

[Anonymous]

Thank you very much, I did not find any overrides in the library. I have already made the assembly without weldments and the weight is OK, so I will let it be. 

[mdavis22569]

There was a problem in 2014, but I thought Update 1 fixed this.

there were a few work arounds, but nothing that I would recommend using repeatly.  

However try replacing component 1 of the items with something that isn't in the file then change it back and see if it will set the weight to what it should be.

Sorry I couldn't help more without seeing the data set..

[J.Landry · Accepted solution]

I know this is a very old topic but it still comes to the top of the list when doing a search for this issue, so I thought I would include what I found to be the solution so that others will be able to reference it.

The root cause is that the volume iProperty has been overridden. By clearing the property and hitting update the real volume is recomputed and the correct density is shown.

 

I hope that this can help someone searching for this in the future.

[yesid_gomez_plata]

Man, that it is the solution I search for a long time. Your answer should be mark green. This problems is reported for many users in different ways and I suspect non of them as same as me know that those values could be override, which is what the hand icon means.

Thanks a lot man!!!

[jeremy_guoin]

I'm also having an issue the the incorrect density in the assembly. But, none of the above fixed my issue. I've checked all the parts, which have the correct density of 8.0 kg/cm3. But, the assembly density is coming up as 5.599. Any other suggestions?

Thanks.

[johnsonshiue]

Hi Jeremy,

The assembly density is actually a computed density. Basically, it is the total mass (from parts), divided by the total volume. It isn't a material-style density.

Unless the assembly contains only one part or its instances, the assembly density will not be the same as the any material density. Please feel free to share an example that exhibits the behavior. The forum experts can help take a further look.

Many thanks!

[jeremy_guoin]

If the densities of all the parts in the assembly are the same, in my case 8.0 g/cm3, then the density of the assembly should also be 8.0 g/cm3. But, in my case Inventor is showing 5.599 g/cm3.

Any suggestions on what could be wrong?

Thanks.

[johnsonshiue]

Hi! I will need to see the files. Please share the files in zip here or send it to me directly johnson.shiue@autodesk.com.

Many thanks!

[J.Landry]

I see a lot of pipe flanges back there. Are there welds in the assembly? If so the volume and density of those is coming into play here and throwing the otherwise homogenous assembly density value off.