It is recommended to use the Share functions in preference to the Copy functions for any parts and assemblies which are used more than once in a model. By sharing parts, you ensure that modifications made to one shared part are automatically reflected in all other shared instances of that part. This sharing of modifications applies not only to changes in the geometry of a part but also to changes in the base settings and other shareable attributes.

When sharing parts or assemblies, the largest proportion of data, particularly data concerned with the geometry of a part, is shared between all instances. Consequently, this shared data exists only once in memory. In addition, a small amount of data must also be duplicated for each shared item, for example, positioning data.

Consider a roller-guide assembly composed of four roller assemblies and a housing. Each roller assembly consists of the following parts:

If you make four copies of the roller assembly, saving them would generate the following 27 files with their associated data volume:

By sharing the retaining bolts and washers in the roller assembly, and sharing the roller assembly four times in the roller guide assembly, you would reduce the number of files (with a corresponding reduction in data) to 7, as follows:

This example shows that by sharing an assembly, and its subassemblies and parts, you require a fraction of the disk space that would be required for a copy of the assembly.

Shared assemblies share the same parts and information about the relationship between the parts; for example, positioning of parts within the assembly. Changing one of the shared assemblies, changing the relationships between the parts, or changing a part in one of the assemblies will change the other assemblies accordingly. On the other hand, the location of a shared part or assembly itself can be changed without affecting the other shares. This is because top-level information (including part color), unique to each instance of a shared part, is not shared. You are free to use shared parts or assemblies within other assemblies.

Occasionally, you may want to change "instance" information (such as positioning or color) for one part in a shared assembly without changing the corresponding parts in the other shared assemblies. This is not possible with normal assembly sharing because the part instances occur only once (they are attached to the shared assembly's unique contents). However, you can create selective instances of components of shared assemblies to create unique instance information while retaining the common, unique contents defined by the shared assembly.

Creo Elements/Direct Modeling allows you to create a sequence of shared duplicates with either a linear, radial, or user-defined offset. If you don't specify a new position for the shared duplicate, it is placed in exactly the same position as the original. You can always move the shared duplicate by selecting it in the Structure browser and using the repositioning functions in the Part & Assembly menu.

You can also unshare shared parts and assemblies at any time. By doing so, you break the relationships between them and create independent parts or assemblies. Any changes made to an unshared part are not transmitted to other parts or assemblies.

To summarize, the sharing of parts and assemblies provides the following advantages: