Synchronous Technology (ST) has been around for four versions now and people are still a little unsure of how and when to use it.
With Solid Edge ST1 and ST2, users were forced into using either totally Synchronous or Ordered (Traditional) modes and, I believe, that this limited the use of synchronous technology to items that were purely prismatic. Solid Edge ST3 introduced the mixed mode and this is where the uptake of ST became a feasible option for a lot of users.
The more I use synchronous technology, the more I appreciate how powerful this technology is. Working on models designed by someone else is always hard work, in that you have to understand how the model was created before you can make any changes to it. Furthermore, making a change on a history based model is always fraught with the danger of subsequent features falling over and dimensions losing their connection to the geometry they are linked to. This all takes time and our modern day workload doesn’t always allow us to “fix up” these little errors that creep in. Over time, a model that has been tweaked will eventually become unusable and so we end up having to re-create it from scratch. Furthermore, when designing in a history based methodology, you need to carefully consider how features are constructed, gazing into crystal balls to determine how a model may change, and building the model to suit.
ST removes the need to understand how a model is generated, as we can just go in and make the necessary changes. Building the model also requires less forethought, as you are not constrained by the creation process to make changes, you can just select the features/faces and change the size, position or rotation.
For example, in an ordered model, this boss was created on a parallel plane, taken from the top base reference plane. Consider the workflow required to change this to rotate it by 45°. The first thing you will need to do is to create the plane that it will sit on. You could just create an angled plane from the base reference planes and project it through the part, but only if the feature has been created in the tree before the cylinder bore has been created. If not, then you need to create an angled plane before repositioning the boss on a parallel plane from the newly created angled plane. Once the boss has been rotated, you may find that the hole has not moved with it, and so you would need to fix this up also. As you can see, the process can become quite lengthy.
In ST, we can fence select the geometry, position the steering wheel on the end face and rotate the three features together, making sure that certain lives rules are switched off (Lock to Base reference, Maintain coplanar faces and maintain coplanar axes).
The essence of using ST is in the understanding of what the technology is trying to do and making sure the Live Rules are adjusted to suit your requirements.
As I stated earlier, ST is a feasible option in most cases, but we have to understand that ST is working with faces and not all situations lend itself to easy manipulation via this means. There are still some situations where modelling is still better (at this stage, although Siemens sound as though they are planning to extend the reach of ST even further in ST5 and 6) in ordered mode. This is the beauty of the way Siemens have implemented Solid Edge since ST3, providing the ability of having mixed modes of operation.
A case study involves creating inter-connecting rounds. While this is a capability of ST, modification becomes near impossible because ST is unable distinguish between faces and, as such, cannot solve the transformation.
The solution in this case is to do the principal modelling in ST and then switch to Ordered mode to apply the rounds. As reasoning engineers, we should be able to see that applying rounds to an area such as this is going to create a lot of inter-connecting faces. When the rest of the model has been created, right mouse click on the synchronous banner in the pathfinder and select Transition to Ordered. The Rounds can now be created using the old history based method. The reason this works is that the ordered based features are suppressed while synchronous edits are made and then reapplied at the end of the edit.