12 Replies Latest reply on Nov 14, 2018 3:28 AM by Marco Janssen

    Mass on PDM card does not match mass in Solidworks. Real life different again...

    John Wayman

      I have placed this in Modelling and Assemblies, despite the reference to PDM in the title, because I think the problem lies in my model, not in PDM.

      Unless you know different...

       

       

      I created a part in SW, and gave it all the usual Custom Properties

      Capture1.JPG

      I checked it into PDM and looked at its data card:

      Capture.JPG

       

      Imagine my surprise when I observed that it weighed 4 tonnes!

       

      I then looked at the Mass Properties in SW:

       

      Capture.JPG

      The sums don't seem to add up - 4908 cubic mm, density 0.01 g/cubic mm - that makes the reported mass in PDM seem very sensible.

      However, SW is reporting a mass of 38.78g.

      I immediately checked and, no, the mass properties are not overridden.

       

      I then did another quick check and, since the diameter is 25mm and the thickness is 10mm, that seems to me as if the reported volume is correct.

      The material is set to 304 stainless, which would make the density 7900kg/cubic m, or 0.079g/ cubic mm.

      Capture.JPG

      That should make the actual mass 785.4 x 0.079 = 38.78g, not 4908.7.

       

      What's going on?

      Where is the density value of 0.01 grams per cubic millimetre coming from?

      Can SW mass properties ever be trusted?

       

       

      File attached, for completeness.

       

      SW2018, SP4

       

      PDM Standard

       

       

      Cheers,

       

       

      John