Your professional pro engineer modeling field it is highly possible that you may be working with similar kinds of components again and again, or may be you are using some of the features very frequently. You should, as a efficient modeling practice, adopt the use of UDF.
By creating UDF you will actually copy all or some of the required modeling data like, dimension, relations and necessary references to a file with your given name and .gph extension. Now when you call this UDF it will ask the references for placement.
Types of UDF
Depending on the method of creation of UDF, it could be classified in following two categories:
1. Subordinate UDF
2. Stand alone UDF
The part from which the UDF is being created determines the dimensions of the subordinate UDF. Whenever the dimensions of the reference part are being changed the same is reflected in the UDF. However after placing the UDF in independent mode, if you change the dimensions of the UDF, it will not be reflected in the UDF library. Means subordinate UDF could be modified after its placement provided you have placed it by clicking the independent option.
Standalone UDF will copy all the reference and relation data from the reference part. And as the name suggest, even if you change dimensions of the reference part, the same will not get reflected in the created UDF.
You can copy the original/reference part while creating UDF in pro engineer, the benefit of this is; you can see the relations and dimensions in that part. The part will be stored after adding _gp with the reference part name.
Creation of UDF
First of all you need to clearly decide the reference part and the features for UDF. While choosing feature for UDF, please remember that, the features which could not be assembly level feature (like round etc.), cannot be used in assembly. So, long and short of it is, if you are in process of defining an UDF and you want to use this UDF for assembly, then you should limited your features by extrusion.
You need to follow the following way for creating a UDF from a part:
It will ask for the name of the UDF, You need to give a meaningful name as the same name will be referred for placing the UDF.
You have to choose the type (subordinate or standalone); the UDF creation dialogue box will open and asks for the feature or components (in case you are creating UDF from assembly). You will be required to specify the placement reference as well. Please be sure to give meaningful names for the placement reference as the same will be required later when you will use the UDF.