6 Replies Latest reply on Dec 14, 2015 6:04 PM by Mike Pogue

    Mass properties when no material is defined

    Loren Sackett

      When I make a part and then go to mass properties it gives me a weight.  Oftentimes this weight (mass) that SW tells me fails the sanity check.  Then I will check and find that no material is defined.

       

      Why does Solid Works spit out a weight when there is no material defined?  Is there a logical reason for it to use the density it does when there is no material defined?

       

      Part of me wishes that SW would throw out a warning when no material was defined rather than throwing out a random/wrong weight.  On the other hand, when I measure the weight of a big assembly, I don't want to have to worry about defining a material for every little bolt, nut and washer.

       

      What do you folks think about this?

        • Re: Mass properties when no material is defined
          Jerry Steiger

          Loren,

           

          I believe that the default material density for SolidWorks is 1 gm/cc. You can set up your part templates to have whatever density you like. Since a lot of our parts are Polycarbonate, I use a value of 1.20 gm.cc. I typically don't define a material, as the clear Polycarbonate appearance isn't good for most of our parts. When I work with other materials I have to remember to set the proper density, unless I go ahead and use a material.

           

          I guess the existing SW way of handling weights works OK for me.

           

          Jerry S.

          • Re: Mass properties when no material is defined
            Kieran Choy

            When no material is specified, the density is 1000kg/m^3 or 0.001g/mm^3 (sorry if you use imperial), which is about the same as water.

             

            If you want to set a default material, start a new blank part, assign the material of your choice (e.g. mild steel) and then Save As a part template. When you start new parts with this template your parts will already have the Mild Steel material (and density) applied.

             

            You can Shift-Select multiple parts in the Assembly Feature Tree and then right-click and apply a material to all of these parts.

             

            If you have SolidWorks Professional or Premium I think you can use Design Checker to ensure models have a material applied to them.

            • Re: Mass properties when no material is defined
              Rob McGivern

              As already stated, SW uses a default material density, even with material has not been added.

               

              My prefered approach would be.

               

              Open new part.

              Then > Tools > Options > Document Properties > Material Properties

              then add some more zeros to the default density.

               

              default is 0.001 kg/cm^3

              I use something like 0.000000001 kg/cm^3

               

              This means the part is much lighter. Then save this part out as a template.

               

              It's the designers job to check they have added material to all the parts. I like to check the weight is correct, but before doing so I will create a BOM with the material as a property. This way I know all the parts have material applied.

               

              Hope this helps

              • Re: Mass properties when no material is defined
                Loren Sackett

                Ahhh, the density of water.  We use imperial units so I did not make that connection.  Thanks for the input everyone.