About Chains
Chains consist of multiple edges or curves that are related, for example, by a common vertex or by tangency. You select these related edges or curves and place them into a group or chain. Chains enable you to efficiently perform modeling actions on all of the selected edges or curves in that chain or on multiple chains at one time.
You can construct chains and use them at any time (within a tool or before entering a tool) during your modeling session. Remember, anytime you want to construct a chain, you must first select a reference, and then press (and hold) SHIFT to activate the chain construction mode. Creo Parametric provides ToolTips, messages, and labels that act as a visual aid to guide you through the chain construction process.
To modify chains, you use the Chain dialog box. This dialog box contains a list of chains that you constructed using the active part and chain attributes and options.
Chain Types
You can create the following types of chains:
• Non-rule based
◦ One-by-One Chain—Chain of individual edges, curves, or composite curves that you select. You can also use a One-by-One chain if you want to model additional edges or curves along with other chains that you constructed. You usually create a One-by-One chain if the elements that you need to select are not part of the same feature, such as a datum curve, or if the elements exist across multiple features. Note that some applications may place other conditions on the resulting chain, such as tangency.
◦ Intent Chain—An intent chain is one that is defined and preserved by the event that created it rather than by the specific entities that it contains. For a simple extrusion with a section composed of entities forming a single closed loop, all the edges generated by the section define an intent chain. If you add or remove entities from the loop, the intent chain is automatically updated as well as any feature that references it.
For example, if you select the edges resulting from the intersection of two solid extrusions as an intent chain to create a round, then the intent chain and the round are automatically updated if you change the sections for the extrusions.
• Rule-based
◦ Partial Loop Chain—Chain that begins at a start-point, follows an edge, and ends at the end-point of the edge or curve segment that you select (also known as a From-To chain). You can construct a curve, surface, or quilt boundary Partial Loop chains.
◦ Tangent Chain—Chain defined by the selected item and the extent to which adjacent entities are tangent.
◦ Complete Loop Chain—Chain that contains an entire loop of curves or edges that binds the curve, quilt, or solid surface to which it belongs, or binds a portion of it as defined by two curves or two edges.
Although points and vertices are considered to be chains by some applications, this is an exception. Most tools discard points and vertices when transferred along with chains into the primary collector. You cannot explicitly convert points and vertices outside of a feature tool into chains, nor can they be extended or modified in any way as chains.