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.
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.
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
We actually didn't want to underestimate mass of an assembly or part so we went the other way and increased the default density by several orders of magnitude so it would be obvious that some parts still needed materials assigned (i.e. 276771 g/cm^3). It works great to identify which parts have been overlooked, especially when looking in Assembly Visualization where you can see the list of all parts and sort highest mass to lowest!
Yeah, much better to have a part weight 1000x too much than to accidentally omit it from the weight budget.
Ahhh, the density of water. We use imperial units so I did not make that connection. Thanks for the input everyone.