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ptc-28486111-Visitor
1-Visitor
September 24, 2014
Solved

Dimensions edition

  • September 24, 2014
  • 1 reply
  • 1886 views

Good morning everybody,

I have a question about the managing of 3D models. We are a plastic industry company and we make our molds.

When we make a mold, we have a 3D model of plastic article in CREO, then We apply a Shrinkage and have parts of mold. Then manufacture all the mold parts, assemble and test until desired plastic parts.

Often the obtained plastic parts in the injection process does not coincide with the plastic article drawing but these plastic parts are good for our customers. In this moment, We edit manually the dimensions in the drawing and then our customer approve this specification drawing.

The problem is that the plastic article 3D model does not coincide with the drawing dimensions. Could you know about the best practice to manage this situation?

We think that our current practice is not good because We are losing the system (CREO)association and is difficult to manage the changes, We have problems for human carelessness.

We appreciate a lot your help.

Have a nice day.


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Best answer by TomD.inPDX

Maybe I overstepped one aspect. the shrunk model can be generated with Creo by applying a scale. You have to be a little careful about this, but for the most part, this will make the final part drawing more correct. Unfortunately, Scale is not a feature so you have to deal with some type of external reference model.

I suspect PTC has a means to deal with this in their mold extension. For the most part, your "master" part should be the final part and all adjustments are only done in the tool making models and process. In this case, when the mold has an unintentional deviation from the master part that is not going to be reworked, the master (final part) model and drawing should be updated to match the final part. Since you made this part in Creo, you should be able to update it accordingly using parametric means. Of course, this also updates all your tool models It is a fine dance, one that your company needs to establish guidelines for.

My consideration for the flexible modeling extension is more geared toward getting models in from outside.

There are people here that deal with this on a daily basis. I hope some of them can weigh in. I look at this from an engineering aspect more than a manufacturer's aspect. Your organization is doing both and somehow they need a process that will work in all instances. I can certainly see a place for the mold extension in your case. This may require some training from PTC to better understand how to utilize the extension effectively in this scenario.

1 reply

J
John.Pryal1-Visitor
1-Visitor
September 24, 2014

Hello, if i am understanding you correctly, it sounds as though you guys are manually creating your dimensions on your drawings instead of showing the driven dimensions used to create your parts. You cannot overwrite driven dimensions only manually created dimensions, & even doing this is bad practice. By overwriting dimensions you are inviting all sorts of problems, whereas, showing only driven dimensions ensures that model & drawing accurately represent one another. I appreciate that manually created dimensions need to be created in addition to the driven ones, but NEVER overwrite them.

John

T
TomD.inPDX17-Peridot
17-Peridot
September 24, 2014

I am going to suggest that the process is A) client provides model B) company creates mold (oversized to allow for shrinkage) C) Parts are not exactly to drawing and is given a deviation approval.

Now how to correct the models if the client is not reworking the drawings to the as-built model.

I'd say you have a great case for using the flexible modeling extension. I think this is one of the best use cases I can think of to justify this.

The only other alternative is to maintain a toolmaster model using a highly accurate 3D scanner on the tool cavities.

Is there a critical need for you to have an accurate model of the as-built parts? If the client is not willing to update their models, maybe it is not a serious issue. If the tool needs to be rebuilt or duplicated, are you again going to try to make it per the original print or are you going to try to make it to the new part? Did the client actually design things that are not "tool friendly" or did the client accept deviations based on tooling costs? This really gets into some really fundamental questions regarding business practice and the practices of the client.

P
ptc-28486111-VisitorAuthor
1-Visitor
September 24, 2014

Thanks a lot for your help Antonius,

Speaking about the flexible modeling extension, we do not have this license. To be clear on the subject, I explain the normal flow in our product development process:

1. We received initial idea of the customer.

2. We model the 3D plastic part.

3. After customer approval, we generate cavities in Tool design extension.

4. We generate drawings for manufacturing.

5. We manufacture and assemble the mold.

6. We tested the mold and adjust.

7. Pilot batch manufacture.

8. Finally we send samples of plastic article to customer with a drawing that match the samples.

The drawing should match the sample plastic parts but normally this drawing does not match of the initial model generated in step 2.

The mold cavities were manufactured with the model in step 2 but to generate the drawing in step 8 we "edit" the dimensions involved in the injection process and we have a "fake" drawing for our customer.

You are understand me?

Could flexible modeling extension help us to generate 2 models, one of these "the original" and the other "the modificated"? I dont know that extension, maybe Im triying using a family table with parent/child relations.

Thanks a lot for your help.

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