Doc ECF 2002 External_References

created by: Eckart Köhler

Design in ContextExternal References

Speaker: Eckart Köhler and Thomas Bach


Part instanceA Part can be used more than one time in a Product. Nevertheless the Part model isstored only once. The system handles Part positions and links on Product level. Therepresentations of the Parts are named instances.

Design in context

Design in context is the methodology of designing inside of a Product structure.

Product

Product

Part Instance

Part Document

PublicationPublication is the capability to give a name to a geometrical element of a Part. New Parts can be positioned and/or designed using published Elements, avoiding direct access to geometry and independently of the product structure. Publication is a method to workwithin “design in context”.


External References

General 01


The following options should be selected before the start:





modifications in thereference Part will implyan automatic update of the contextual links





1) Open the Product „ExternalReferences.CATProduct“

2) Activate Part Body of PLM_0114 by double click.

3) Select the plane as shown below and activate the sketcher.


4) Select the red geometry as shown in the picture. These lines are from thePart „PLM_0115_2 Fertigteil“.

5) Select function „Project 3D Elements“.The selected geometry will be projectedon the sketch plane of the Part PLM_0114.


Also the icon in the tree changes from yellow to green.

Take a look at the tree of Part PLM_0114 - a new folder withthe name External References was created automatically byCATIA.The green point of the curve icon indicates that the link issynchronized.


6) Close the sketch profil as shown below.

7) Repeat the steps 4 to 6 on the othergroove.


8. Create a pad. The First Limit should be up to plane.

Select this plane as limitation plane.


9. The result looks like this:

Each external reference can beisolated or deactivated by thecontextual menue.


Repeat the steps 1 to 9.


External References

General 02


Product level (Icon (gear symbol) in front of a part instance)

Part level

keine externen Links no external link

Link zu einem element ist aktualisiert Linked element is updated

externe Links: Kontextbauteil ist in seiner Erzeugungsumgebung geöffnet external link; contextual part is opened in the creation environment

Link zu einem element ist nicht aktualisiert Linked element is not updated

externe Links: Kontextbauteil ist nicht in seiner Erzeugungsumgebung geöffnet external links; contextual part is not opened in the creation environment

Element nicht mit Link versehen oder Link unterbrochen element not linked or link broken Referenz Element nicht geladen Referenz element not loaded

Link zu einem „published“ element ist aktualisiert Link to published element updated

Link zu einem „published“ element ist nicht aktualisiert Link to a published element not updated

Detect and analyze links

R8/R9


10. Change into Part „PLM_0115_2 Fertigteil“ bydouble clicking the face as shown below.Once more and the pocket definiton panel appears.

The parameter of the sketch can beedited directly by clicking the singlevalues - without opening the sketch.


11. Change parameter length 60mm to 62mm (double clickPocket.3). Also the parameter 2.5mm to 4.5mm (double clickPocket.4).

After leaving to pockets definition panels by clicking ok, thegeometry colour of „PLM_0115_2 Fertigteil“ turns to red. Press update button. After that, the geometry of „PLM_0115_2 Fertigteil“ turns to gray, but the colour of PLM_0114 turns to red, because thechanges of PLM_0115 ... causes a change of PLM_0114.


12. Update the Part PLM_0115... . The result looks likethis:

Before updating the Part PLM_0114 check the result in the geometry (red circles).


12. Update the Part PLM_0114. The result looks likethis:

The geometry of Part PLM_0114 changes, because of the used External References.


13. Activate PLM_0114

14. Select the function Edit/Links:

The External References are listed in this spreadsheet. To see the pointed documents, switch to „Pointeddocuments“.




External References

Loop design between geometryand constraints


2) Select the two faces as shown below:

1) Open Product „External References_1.CATProduct“ and activate Assembly Design workbench if required.

3) Select function „offset constraint“.The following message appears:


CATIA doesn‘t create an assembly constraint, if a geometricaldependency already exists BUT this limitation is limited to thedirection/axis in which the geometrical dependency (by ExternalReferences) was created.

4) Select the two faces as shown below:

5) Select function „offset constraint“.The following panel appears:


Now CATIA can create an assembly constraint, because there is no geometrical limitation in this direction/axis.

6) Change the offset value to 20 mm. The position of Part PLM_0114 will be changed.


7) Select the following face and double click on it to activate thePart PLM_0115 ... .

8) Activate the sketcher on this face.


9) Select the function „Project 3D Elements“.

10) Move the cursor over thegeometry of Part PLM_0114 - a blacksign appears.


CATIA cannot create a second „reverse“ dependency from Part PLM_0114 to Part PLM_0115..., because it already exists a dependency from Part PLM_0115... to Part PLM_0114.


Open the file/desk function, to see the following picture:

External_References_1.CATProduct

PLM_0114_1.CATPart

PLM_0105_2_Fertigteil_1.CATPart

PLM_0106_2_Fertigteil_1.CATPart

*

MetricThinPitch.txt

MetricThickPitch.txt

In the tree you can see, that PLM_0115_2 Fertigteil_1 is a child of PLM_0114_1. Than PLM_0114 cannot also be a child of PLM_0115... (as in real live also).




External References

General 03


11) Exit the sketcher.

12) Select the face and double click on it.

13) Activate sketch function


14) Select geometry as shown below and the function„Project 3D Elements“

15) Create a pocket with the depth of 1mm.


16) Create a chamfer with the lenght.1 = 1mm and the angle 45deg.

The result should look like this:

17) Repeat the steps 12 to 16 on the hole of the othergroove.


18) Activate the main Product.

19) Edit the offset - newvalue = 30mm

20) Check the result. The two newholes in Part ... 114 have a newposition - also the chamfersmoved with the holes.




External References

General 04


Weeks later its not easy to remember which external referencepoints the which Part or geometry. You can avoid this by using theparent children command.

a) Open the folder „ExternalReferences“ of the Part ...0114

b) select curve.43

c) press right mouse button and select „parent children“.


The following panel appears:

The message:Curve.43 has a parent edge which is located in Part PLM_0105_2_Fertigteil_1.CATPart and a child, which is inside theactive Part with the name Setch.42.

Activate the edge and press the right mouse button- select reframe on and the curve is highlighted in the 3D workspace- select center graph, to visualize the corresponding feature in the tree


As we have seen by the last command, hole.14 is the parent of curve.43.

21) Activate Part PLM_0105... and select hole.14 in tree.

22) center the tree, that the External References are visible(be sure that hole.14 is still selected)

23) Press delete on thekeyboard. An update isrequested - update Part PLM_105....


24) After the update of Part PLM_105... the Product looks like this:

The icons of the External Referenceshas been changed.The icons of the curves 26 to 42 arered which means, that they have to be synchronized (which happensautomatically after the update of Part PLM_0114...).

The icon of curve.43 is different. This symbol indicates, that thereference is lost - in this casebecause of the hole.14, we deletedin the last step.


25) Activate Part PLM_0114... and update it. The followingmessage appears:

Curve.43 is now whithout any connection to a parent geometry. But the children(pocket.14 and chamfer.14 - check by parent/children) are still connected.To reconnect the curve with a new external reference do the following:a) create a new hole in Part PLM_0105... with a thread M3 inside and the optionup to next.b) activate Part PLM_0114...c) create a new external reference. An easy way to do so is to create a point on the selected new curve, which should be the new external reference. After that, delete the point and the new external reference is in the Part.d) select curve.43 and activate by right mouse button the replace command -select the external reference which was created in step c).e) curve.43 can know be deleted.


The tree than looks like this:


26) Open a new Product an insert the existing Part PLM_0114_1.

The green wheel turns into brown. Thatmeans, this Part is a contextual Part, butit is inserted in a Product which is not the„base“ contextual environment.

Therefore this errormessage also appears:


To find the name and path of the „base“ contextual environmentdo the following:

a) activate PLM_0114_1

b) Select Edit/Links from the menue and change to pointeddocuments:


A child always knows its parent, even if they are located in otherPart/Product BUT a parent feature/geometry doesn‘t know itschildren, if they are not in the same Part.

Example:a) Open the Product „External References_2“b) Open the tree of the Part PLM_0114_2 and the folder ExternalReferencesc) Select curve.44 and select in the contextual menue theParent/Children command


d) Parent of curve.44 is one edge of the Part PLM_0105_2 Fertigteil.

e) Select the edge in the panel an press right mouse button/centergraph - hole.18 of the Part PLM_0105_2 Fertigteil is highlighted.

f) close window, double click on hole.18 and select in thecontextual menue the Parent/Children command - hole.18 knowsnothing about its child curve.44.


- repeat the steps 21 to 26

- check the hints and tips


External References

Reference linksand

Instance links


The difference between an instance link and a reference link will beexplained on the following example:

1) Open the Parts „Reference link_PLM_0105“ and „Referencelink_PLM_0114“. HINT: These Parts are opened without a Product.

Reference links


2) Activate the Part Body of the Part „Reference link_PLM_0105“, select Sketch.40 of Pocket.3 and press right mouse button/copy.

3) Activate the Part Body of the Part „Reference link_PLM_0114“, and press right mouse button/paste special. Select the option „asresult with link“.

Reference links


CATIA has inserted the sketch.40 of the Part „Referencelink_PLM_0105“ with a reference link.Check the icon of the inserted sketch - the green point indicates, that a link exists.

Reference links


4) Create a pad as shown below.

Reference links


5) Select Window/tile horizontaly.Activate the Part Body of the Part „Reference link_PLM_0105“, select Sketch.40 of Pocket.3 and edit the parameter with the value60mm to 62mm and exit the sketch.

Reference links


Both geomtries turns to red

6) Update both PartsThe groove in Part PLM_0105 and the padin the other Part changes because of thereference link.

Reference links




Using a reference link results in a geometricalParent/Children dependency between two Parts BUT thepositions of these Parts in an assembly have no effect on this kind of links.

Reference links


Instance links

1) Open the Product „External_References_2“. This is the Productwe created already.Remember, the geometrical dependencies between thegrooves/pads and the holes were created in the Productenvironment.


2) Double click on the face below:

3) Change 62mm to 60mm and press ok.Update the complete Product.

The gemetrical dependencybetween both Parts is still alive.

Instance links


4) Now select the instantiation of PLM_105... in the tree:

5) Select the compass and place it on the Part PLM_0105.... The compass turns to green.

Instance links


6) Move the compass (Part) -2mm in x-direction as shownbelow and update the Product. HINT: To do so activate the contextual menue of the compass.

We have just changed the relative position of the Parts to another with the effect, that the geometry changes in the childPart PLM_0115... .

Result:

Instance links




Using a reference link results in a geometrical Parent/Childrendependency between two Parts.BUTThe position of the Parts in an assembly has no effect.

Reference links

Instance links

Using an instance link results in a geometrical Parent/Childrendependency between two Parts.ANDThe position of the Parts in an assembly has an effect.


In the examples of this chapter we have always created externalreferences which were based on edges, faces and vertexes.

Depending on the assembly that has to be created, it can beusefull to create a „Master Part“, that includes lines, points and surfaces, which drives other connected Parts.

The advantages of this method are:- clearly arranged structur within the assembly- problems with missing edges, faces or vertexes (caused by somespecific geometrical changes) can be avoided

The disadvantage is:- each driving geometry has to be transfered into the „Master Part“

Doc ECF 2002 External_References

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