SolidWorks 2011 Assemblies Bible - Matt Lombard [36]
Dissolving subassemblies
If you would like to get rid of a subassembly but want to keep its parts, then you can use the Dissolve Subassembly option through the RMB menu. This option has some of the same consequences of the Form New Subassembly Here option in that mates are moved from the subassembly to the upper-level assembly, and you may lose in-context relations and assembly features.
Organizing for performance
In SolidWorks, performance refers to speed. Subassemblies can contribute to speed-saving modeling techniques by segmenting the work that the software needs to do at any one time.
Solving mates
The mates that contribute to putting the pieces of an assembly together are solved at the top assembly level. Under normal circumstances, subassemblies are treated as static selections of parts that are welded together, and their mates are not solved at the same time that the top-level assemblies' mates are solved. This segmenting of the mates leads to improved performance by only solving one set of mates at a time.
Mates are usually solved as a single group unless there is a special situation, such as mates to in-context features, component pattern instances, or an assembly feature, all of which have already been described in this chapter. When one of these situations occurs, the mates have to be divided into separate groups or solved multiple times. This is done behind the scenes so that the user does not have to worry about it. Multiple rebuilds affect the user only in terms of rebuild times.
Using flexible subassemblies
When you put a subassembly into an upper-level assembly, the mates for the parts of the subassembly are not solved in the upper-level assembly. This means that if a subassembly is a mechanism, the mechanism does not allow Dynamic Assembly Motion in the upper-level assembly, and it is considered rigid. For example, in Figure 4.7, the front fork is a linkage mechanism, but it is also a subassembly. Without reassembling the parts of the fork in the upper-level assembly, you can allow the mates from the fork subassembly to be solved in the upper-level assembly by using the Solve As option in the Component Properties dialog box, shown in Figure 4.7. When you select the Flexible option, you enable the mates of this subassembly to be solved in the upper-level assembly, which allows the parts of the subassembly to move in the upper-level assembly. To access the Component Properties dialog box, right-click the subassembly and select Component Properties from the menu.
Flexible subassemblies have become more reliable and easier to use over the last several releases of SolidWorks. You should work with them or do some experimentation to see if they assist your modeling process. If you find they cause trouble in some situations, they are easy enough to deactivate.
Working with legacy data
If you have assemblies that were built in older versions of SolidWorks (such as SolidWorks 2001 and later), you should know that mates used to be split up into multiple mate groups, which represented the groupings that mates were solved in. This was forced by mating to the history-based features in the assembly FeatureManager. SolidWorks no longer displays mate groups, but the groups are still used in the background to solve mates. This is another change that SolidWorks has made to the software that simplifies the user's interaction with it, but it also makes it obvious that things are now happening behind the scenes that you can't control.
FIGURE 4.7
Creating a flexible subassembly
Organizing for the Bill of Materials
The Bill of Materials, or