User Defined Features vs Family Tables

[J_E_Hyde]

I could use some help understanding the differences between User Defined Features and Family Tables, working in Creo 10, how you choose which to use when trying to standardize/parameterize a particular component or feature, and why you would use a User Defined Feature that contains (or otherwise references) a Family Table or vice versa. 

Here is my current understanding of the differences:

• User Defined Features
  • Created from features in a part file, may or may not maintain references to it (subordinate/standalone)
  • Creates a .gph file
  • Used with a series of defined prompts that relate to feature parameters (dimensions etc) and placement in the model using it
  • Instances as a body or a modification to a body
• Family Tables
  • Based around a generic ancestor part file
  • Creates additional part files as you create instances
  • Used by assembling instances of the relevant part file
  • Instances as a part

[KenFarley]

User Defined Features, as far as my usage goes, are completely unrelated to Family Tables.

A family table is used to specify different versions of a part or assembly, where you want to vary dimensions, exclude or include specific features, etc.

A user defined feature is the grouping together of operations to perform a tedious or complicated bit of geometry creation. For example, I've used this in the past to repeat the sequence of operations necessary to create a custom hole normal to a surface, located with a point in 3D space. I grouped all the features needed to "build" one hole (define axis through point normal to surface, make plane thru point normal to axis, etc.) and saved them as a user defined feature. The UDF was then available to build the remaining 80 or so holes in the part.

Others may have different uses of the UDF that I haven't experienced, but this is how I understand them.

I only use UDFs when I absolutely have to, because defining them is somewhat of a challenge - you have to be very careful about making sure your required geometry entities is minimal and robust.

[tbraxton]

I would describe the differences at a high level to be the following.

UDFs are a group of features that can be reused by adding them to a model when required.

Family tables are used to create parametric variations of a generic instance of a model.

Building useful (easily placed into a model) UDFs requires a high degree of proficiency with Creo. Creating family tables is easy but one can create a mess if they are not well planned. There are known Windchill issues with family tables as well. Parent/child relationships can become convoluted with the use of either method.

It depends on how you want to manage design intent and reuse of design data within Creo. There can be overlap between the two options in terms of functionality but one or the other would become preferred based on the specific application. Given a design problem one would usually become the preferred method rather quickly based on the design intent definition and the reuse requirements.

Note that Creo does support UDF family tables. I have never had cause to use one, but I can conceive of scenarios where they would be useful. If you are new to Creo I would not jump directly into the use of a UDF family table for any real work. You should have a good understanding of UDFs and family tables before combining them.

To Create or Modify a UDF Family Table

I would also point out that with the introduction of multibody functionality in Creo 7 and the ability of copy geometry to reference a body adds another option that overlaps heavily with UDF functionality. You can now copy a body bringing in complex geometry without the reference/regeneration overhead associated with a UDF. I have leveraged this functionality to copy geometry into designs more quickly than a UDF with the same geometry. This method also enables the toggle of parent child dependency to the source file if needed. In the target file there is no direct access to the features used to create the imported geometry so this may be considered a limitation vs a UDF. 

[Chris3]

We use UDF Family tables for things like D-SUB punch outs.

I agree with everything that has been said. Just to throw another wrinkle into the mix, Creo 12 now allows you to store sketches / feature values with presets.