Casting models and machining models

[asecker]

Hi,


I was interested to know what kind of techniques people use to model castings and then the machined versions of the cast part.


I tend to use family tables. I create all the machining details as surfaces as close to the beginning of the model as I can. I then create the casting model around these surfaces (but not necessarily referenced to them). I then solidify the model. I then use the solidify command to cut away all the machining detail. I then group all these cuts together and create a family table. Its then just a matter of turning these cut features off to create the casting instance to send to the foundry and turning them on in the machining instance to send to our machine shop.


Is this a technique other people use or is there a better one. I've seen inheritance and merge features used also.


Cheers,


Adam

 

[dr_gallup]

I like the merge better because it enforces the separation cast & machined parts. Particularly if you are machining several parts from one casting.

The family table thing works well but you have to make sure that all the features end up in the right parts. When I do it by family table, I take the opposite approach, I create the casting first then every feature in the machined part removes material.

 

[design-engine]

I teach people to use any number of top down modeling techniques like dr-gallup suggests.

It maybe better to take it another step and publish the geometry as well. I would suggests a copy geometry and a naming convention like:

part_number.prt.1 < the generic part
part_number_machined.prt.1 < the machined part. This part looks at the publish geometry of 'part-number.prt.1'
Edited by: design-engine

 

[SRINIVASANIYER1]

Long time back I had posted an article on the same subject here in mcadcentral at...
http://www.mcadcentral.com/proe/forum/forum_posts.asp?TID=36 605&KW=inheritance+feature
The file is no more available for download.

The procedure was to use the Inheretance feature instead of Family tables or publish geometry.

I shall see where I can get it.

 

[Jacoolo]

inheretance feature requires AAX extension if I remember right. That is first.

Second - they produce a lot off tricky external references which could - not must - cause a lot of problems in PDM software - expect a lot off ghost object while fetching models driven by inheritance features.

At the end I would favourite merge or Copy Geometry from other model.... The last one has this advantage it lets You choose exactly what do You want from rough part model. Merge will take all, even layers!

 

[asecker]

Hi,


I am using Intralink so ghost objects are something I'd obviously like to avoid.


Dr_gallup mentioned something which appliesto the component I'm working on at the moment. I'm working on an engine camshaft coverand I will use the same casting to machine a RH camshaft cover and a LH camshaft cover. Maybe using family tables will be too confusing?


The merge/published geometry method sounds interesting. Could anyone explain in more detail how to use it? Note that I currently have one model containing all the machining and cast features so I'm at the point where I need to decide which way to jump.


Many thanks,


Adam

 

[Jacoolo]

well your current approach tends to produce a lot of extra work to maintain every change regarding such model in order. I do not envy you to work with such geometry.

Instead, I would make first a rough part model, which contains only casting geometry. This is simple as long you have prepared drawings or any other resource of such geometry. If you are working on prototype device, then it is normal machined geometry comes first and rough second.

But, let`s assume rough part geometry exists. Then you name this model with a same number but extra digit, let say "R". Now make a new, blank model in Pro/E with extension, let say "M". In this new blank model make as following:

*go to Colors and appearence > choose Red color for whole Part

*Insert > shared Data > Copy Geometry > open target rough part model. Choose any surface, PPM > Solid surfaces. If necessary copy required datums, axes, etc > then OK.

*switch Quilt in filter selector > pick copied geoemtry > Edit > Solidify

*go to Color&appearence > choose grey color > pick a surface > PPM > solid surfaces > Apply color to it

now You can perform all necessary machining cuts. All removed geometry will be automaticaly displayed with red color.



Edited by: muadib3d

 

[SRINIVASANIYER1]

Has anyone tried the neutral file (.neu) route? One can save the machined or cast component as a .neu file and then build the machined component over it. I read somewhere that with ATB, the link is maintained. Need to try. Only with any changes to the Casting model, one may have to save a .neu file so as to reflect the changes in the machined part.

PTC recommends "inheritance feature". Yes, inheritence feature requires AAX.

 

[Jacoolo]

Srini

all is fine regarding nuetral format as long You accept lack of associative link in between.

Second - small round in casting part, will produce gaps in neutral format.

Third - neutral format like *.step are text file, very big, if the contained geometry consits of many small surface.

Fourth - you double - at least - data count in your pdm environemnt:

*org casting file

*neutral format casting file

*machined part

I know that some firms used to use assembly to make machining cutsm because these are only solid features you can make at assembly level

so it was like adding casting part as component and then making all these cut on assembly level.

 

[asecker]

muadib3d,


I can understand the advantage of using the merge/published geometry method as described but having the machining features and castingfeatures in one modelappears to be very useful as you don't need to go backwards and forwards between models.


Could I group the machining surfaces at the end of the model and use published geometry to call them into the machining model? Is this what Bart was talking about?


Thanks,


Adam

 

[asecker]

Hi,


I've been looking at the insert > shared data > merge option this afternoon as it seems like the way to go.


Can anyone help though? If I change the name of a datum plane in the referenced part (my casting) it doesn't update in the merge feature within my machining model. I've tried un-ticking and then ticking the copy datums option under references but I can't get the name to update. Feature updates come through fine. Am I doing something wrong?


Thanks,


Adam

 

[SRINIVASANIYER1]

OK....
I could get hold of the file. Have a look at it. I shall be happy to receive comments.

2011-03-06_021055_2008-03-27_034131_Designing_Cast_and_Machi ned_component_using_Inheritance_feature.zip

 

[asecker]

Srini,


Many thanks for finding the file.


I guess a merge would work just as well? Other than being able to see the whole model tree, what advantagesdoesusing theinheritance feature haveoverjust using a merge when used in this casting/machining model application.


If I find it useful to model the machined surfaces within the casting model do you think it's acceptable to select thesesurfaces in the machining model and use the solidy command to remove material?In other words, the only features I would have inmy machining model would be solidify features?


Thanks,


Adam

 

[SRINIVASANIYER1]

I guess a merge would work just as well? Other than being able to see the whole model tree, what advantagesdoesusing theinheritance feature haveoverjust using a merge when used in this casting/machining model application.

The answer to your question as it comes from the horse's mouth...
https://www.ptc.com/appserver/cs/view/solution.jsp?n=110817
https://www.ptc.com/appserver/cs/view/solution.jsp?n=108255

As for the ghost objects another link...
Ghost Objects

Edited by: SRINIVASANIYER1

 

[asecker]

Srini,


Unfortunately our company doesn't have a current maintenance agreement

Is there any other way you could forward the info.


Many thanks,


Adam

 

[SRINIVASANIYER1]

PM me your email ID.

 

[asecker]

Hi,

Following comments received from my initial post I've been using the inheritance feature option to create my machining model from a casting.

All seems to be going ok but it seems a fairly slow method.

If I want a new maching feature I like to be able to just place the surface where I need it. Using the inheritance feature I have to then go back to my casting model and place cast material to support the feature. Then I have to go back to the maching model, update the inheritance feature and check wall clearances. If it's not quite right I then have to go back to the casting model......

Basically, all this going backwards and forwards seems really slow. I can't help but think I should have stuck with the family table method. Maybe I can improve my method tho?

Any comments would be gratefully received.

 

[SRINIVASANIYER1]

For me, the inheritance is the preferred way.That way I ensure that both casting and the machined components are designed correctly.
You can add the machining feature in a new location in the Machined model, provided you have material there, which will come only from the casting. We prepare DIFFERENT drawings for Casting and Machining. While the casting drawing goes to the pattern maker, the machined version goes to the Machinist.
As for going back and forth, I believe you can add features in the inheritance model within the realm of Machined Model. I will have to check this though.

I use the same method for Fabrication and Machining.

 

[dr_gallup]

I guess a merge would work just as well? Other than being able to see the whole model tree, what advantagesdoesusing theinheritance feature haveoverjust using a merge when used in this casting/machining model application.

The answer to your question as it comes from the horse's mouth...
https://www.ptc.com/appserver/cs/view/solution.jsp?n=110817
https://www.ptc.com/appserver/cs/view/solution.jsp?n=108255

As for the ghost objects another link...
Ghost Objects

Description

-----------------

Why Use Inheritance Features?





Alternate Technique

-----------------

See Resolution Below





Resolution

-----------------

Inheritance Features are very similar in nature to merge features and
copy geom, only with increased access to the copied feature information.
An Inheritance Feature allows a one-way associate merge of geometry and
feature data from one part to another. Inheritance Features are
always created by referencing existing parts. An Inheritance Feature
begins with all of its geometry and data identical to the part from
which it is derived, however without changing the Base Model, the
Inheritance Feature can contain different dimensional values and statues
for features.



****



Inheritance Features can be used in place of Family Tables.



Instead of creating a family of instances, each of which includes
characteristics for the whole family, a inheritance feature can be made,
which is a generic "base" object, with additional "action items"
applied to its features. These actions could be anything from modifying
dimensions to suppressing features, etc.



Inheritance features will avoid the problem of revision bumping on base
(generic) models, and "sibling" derived objects (meaning two objects
stemming from the same base model) since they do not have to carry the
weight of each other's unique characteristics.



****



Inheritance features can be used in Place of Copy Geom.



Inheritance features will allow a direct reference to a top-level
skeleton, with access to all of its features. An Inheritance feature
would be used when many elements of the top skeleton are needed; an
External Copy Geom method would be used for smaller-scale needs.
Further, Inheritance Features allow full access to the feature
information, where Copy Geoms and External Copy Geoms do not.

**************************

The part in red is why I don't use inheritance. You can change it all around in your downstream model and the parent never changes. So if you think you can successfully make the machined part from the casting you could be in for a big surprise when the machinist brings you a part with a lot of holes in it where you wanted metal.

 

[asecker]

Dr Gallup,

Thankyou for your comments. You seem to be suggesting that its easy to make the inheritance feature different to the base model by accident though. If you try to alter a dimension in the inheritance feature Pro/E seems to give you ample opportunity to make the correct decision.

My intention in starting the thread was to discover the quickest and most robust way of modelling a casting and machined model.

From the responses, I think if I was modelling a casting which was only to be used to create one machined part I would use family tables. I could then throw the majority of my machined surfaces in at the start of the model and build my casting around them as surfaces. I'd then solidy the casting quilt at the end and then use the machined surfaces to cut material away using the solidify command at the end. I could group all these machining cuts and then use a family table to create the casting and machined model as separate parts. This would prevent having to go backwards and fowards between models and would save lots of modelling time. Updating inheritance feaures seems to take a long time!

Maybe if I was using one casting to create more than one machined model family tables would get a little complicated though? Perhaps then I should use either merge or an inheritance feature?

It would be great if we could come up with a fool proof method for what must be a fairly common modelling requirement.

Thanks, Adam.