Watch your Weight!

Catalog items such as bearings, cylinders, electromotors, and gearboxes often get imported with incorrect mass values. Although the mass may be overridden as we import the model, it can still be incorrect. Here is a comparison between imported and actual mass for an SKF bearing:

model mass comparison

Using an item with the wrong mass in your assembly can lead to incorrect assembly mass, which in turn affects all upper-level assemblies. To compound the issue, the mass is typically displayed in the title block, which means that any associated drawings will also be incorrect.

For instance, I once overlooked verifying the weight of a lifting table model. The error wasn't just 1 kg or 10 kg - it was off by 600 kg! This meant that the lifting table weighed not 600 kg but 1200 kg. Unfortunately, this went unnoticed for some time. By the time we found the mistake, the lifting table model had already been used in approximately 20 other assemblies, all of which had already been released. As a result, we had to revise 20 models, 20 drawings, and a few Excel BOMs to correct the mistake.

As demonstrated, mass is a critical property that affects assemblies, drawings, and other documentation. When designing on a computer, we may have poor judgment of how large or heavy an item is, which can lead to such errors.

So, why is mass so important that we had to dedicate an entire blog post to it? Here are a few reasons why incorrect mass values can cause problems:

  • flawed design in case of mass optimization
  • inaccurate transport cost estimates
  • unreliable CAE results
  • incorrect transport and handling instructions

To minimize the likelihood of such errors, here's one idea:

  • When downloading a neutral file (step, iges,…) from the web, check the item's mass and include it in the filename as you save it. For example: “SKF bearing 6013-2RS1 0.45kg.step“

  • The mass will automatically transfer to the Solidworks file’s filename, eliminating the need for further website searches. For example: "SKF bearing 6013-2RS1 0.45kg.sldprt".

  • If you can't find the mass (which can happen), you can add a note to the filename such as "MASS MISSING" to indicate the need for verification before proceeding with the drawing release.

  • Once you are certain which catalog items you will use in your project, you can take the time to override the mass in Solidworks for those specific items. This way, you won't waste time overriding the values of unnecessary items.

  • This approach also gives you the possibility to compare the mass in the filename with the mass in the model as one of the final steps before you release the drawings. This can be done with or without PDM.

Correcting the mass of imported models is just one step towards creating accurate technical documentation. If you're interested in learning more about the Release Procedure Checklist we employ at JRP on a daily basis, feel free to contact us at or via LinkedIn.

About the Author

Barbara Jerin

Is the creator of this blog and author of the majority of blog posts.

Comments 1

  1. Hi Barbara,

    Good topic and one that I often encounter with customers.
    I have customers that create VERY large equipment which they have to perform seismic calculations therefore making it important to have an accurate mass. Although I’ve never considered or suggested they add the mass into the file name it’s not a bad idea. I like to include a weight field on the PDM data card, set the text as red and make it zero. This helps to make it easier to see if it’s been added to the model. But that is still something that has to be looked at to be noticed.


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