Assembly Delighters with SOLIDWORKS 2021

On every new release of SOLIDWORKS, we are always looking forward to those subtle but yet very useful changes that affect our everyday SOLIDWORKS life. We all know that SOLIDWORKS is always looking for great ways to increase your productivity and help you not just get to market faster, but smarter. What better subject to discuss a few of those new very valuable features than using Assemblies. Several great new features and functionality were introduced in SOLIDWORKS 2021. Some of the features are truly game changers but in this case, we will be discussing three Assembly Delighters.

One of the extremely necessary MUST DOs on any assembly created in 3D CAD is to check for interferences. SOLIDWORKS has had for a very long time the very useful Interference Detection Tool found under the Evaluate Tab while in assembly mode. I know that this tool has saved many projects from complete fabrication failures. So what else could be done to improve this fantastic functionality? Yes, you guessed it, Exporting Interference Detection Results!

SOLIDWORKS 2021 now offers the option to save these interferences out in a spreadsheet. You can even save a thumbnail for each of the interferences as it also contains the part groups that are interfering with each other.

This is a great new feature since it can be used and shared as a checklist of the items that might be intended interferences or to be able to make the proper design changes to correct these interferences. This document, if using a data management solution like our very own SOLIDWORKS PDM, can be also included in the project workflow and revised accordingly to keep a history of the changes and reason for such changes during the project.

Of course, being a csv or excel document, this can also be further edited to completely correspond your company’s requirements. What a great way to stay informed with critical assembly data!

Let us now talk about Assembly Performance. When working with assemblies, a large assembly might be one with 10 or 10,000 components depending on many possibilities such as file sizes of components, hardware, or file storage infrastructure. There are many options to help with opening and working with large assemblies, but one of the very helpful and common form is using Lightweight Mode. When a component is lightweight, only a subset of its model data is loaded in memory. The remaining model data is loaded on an as-needed basis. You can improve performance of large assemblies significantly by using lightweight components. Loading an assembly with lightweight components is faster than loading the same assembly with fully resolved components. Assemblies with lightweight components rebuild faster because less data is evaluated. Only components that are affected by changes that you make in the current editing session become fully resolved.

You can perform the following assembly operations on lightweight components without resolving them:

⦁ Add/remove mates
⦁ Edge/face/component selection
⦁ Assembly features
⦁ Measure
⦁ Section properties
⦁ Mass properties
⦁ Exploded views
⦁ Physical simulation
⦁ Dimensions
⦁ Interference detection
⦁ Collision detection
⦁ Annotations
⦁ Assembly reference geometry
⦁ Section views
⦁ Advanced component selection

When a component is lightweight, a feather appears on the component icon in the FeatureManager design tree.


To open an assembly or even an assembly drawing using lightweight mode:

Click Open  (Standard toolbar) or File > Open.


1. In the dialog box, select the assembly you want to open, and then in Mode, select Lightweight.
2. Click Open.

You can set a system option to open assemblies in lightweight mode by default. To enable automatic lightweight loading of components:

1. Click Options (Standard toolbar) or Tools > Options.
2. On the System Options tab, select Performance.
3. Under Assemblies, select Automatically load components lightweight.
4. Click OK.

If you have not been using Lightweight mode, we strongly suggest trying it and you will notice a difference in opening times right away.

What’s new about Lightweight Mode in SOLIDWORKS 2021? For assemblies now opened in lightweight mode, top-level components and subassemblies resolve automatically when you click to expand the item in the FeatureManager® design tree. Components in subassemblies remain in lightweight mode until you expand them.

This will be extremely useful and no reason why not to use the automatically load components option. Eliminating having to RMB click on each subassembly or component and selecting to set resolved to lightweight.

While on the subject of saving time while opening or closing files, working with configurations in 2021 is also much faster. You will notice that switching between configurations on files that have been saved as 2021 files will now be significantly faster.

Overall, SOLIDWORKS 2021 focused a lot on Performance, we recommend this Assembly Performance Video that provides additional details about what you might be missing out if you are not yet using SOLIDWORKS 2021 and working with assemblies or assembly drawings.


Juan Chapa

Juan Chapa has been using SolidWorks since 2006 and his background includes design and simulation in heavy machinery and food processing equipment. Juan worked as an Elite Application Engineer with a SolidWorks Valued Added Reseller for 12 years assisting customers with training, technical support, and implementation services. He joined the DASSAULT SYSTEMES SolidWorks team as an Industry Process Consultant in March of 2020. Juan resides in the Rio Grande Valley in the great state of Texas and specializes in 3DEXPERIENCE Works, Data Management, Simulation, and SOLIDWORKS Electrical.

Latest posts by Juan Chapa (see all)