Practices for handling cut-to-length parts with Creo and Windchill

[N-Pyn]

Hi everyone, 

Almost every design and manufacturing company uses some parts that are created by cutting some stock material (pipe, hose, aluminium extrusion, etc.) to a defined length without any other machining or other processing. Of course there is no need or sense in creating drawings for these kind of parts because the drawing would only tell what material to use and what length to cut it to.

At the moment our method for handling these is by first modeling the part in Creo with any way the engineer is used to and then creating a WTPart automatically during check-in.

Next the engineer goes to Windchill and adds a stock material WTPart to the structure of the new WTPart and sets the quantity of the BOM row to match with the length of the model. 

Here is an example of the resulting WTPart structure:

This is not a great method because if the length of the part is changed, it needs to be updated in multiple places: Model, part name and BOM row quantity. Also sometimes the engineer might forget to add the stock material item to the BOM.

What kind of workflows and practices do you have for handling these kinds of parts from Creo to Windchill and to ERP?

[Van_AG · Accepted solution]

Look at the bulk item components

https://support.ptc.com/help/creo/creo_pma/r11.0/usascii/index.html#page/assembly/asm/About_Bulk_Items.html

I think this is the best practice in the case

[N-Pyn]

I have thought about this also and it seems to be the most promising option at the moment.

I was thinking that I could create templates for the parts created from stock material which would have a LENGTH parameter driving the model length. Then when engineers add a copy of that template to the assembly, they would have to also add the bulk item of the stock material. And then define the quantity of the bulk item with a Parameter Sum of that LENGTH parameter of all those parts to get the total need of the stock material. Bulk item would be associated to the WTPart of the stock material and the part created from the stock material would not have any WTPart associated to it.

The cutting lengths of the materials would be described in the assembly BOM and the WTPart structure would only give the total material reservation of each used stock material.

The problem with this would be that it seems that it would only work with stock materials that are measured in meters. It seems that Creo->Windchill integration converts the usage quantity of the stock material to meters even though the default quantity unit of the associated WTPart is cm or mm. We would have to add some unit conversion logic to our integration platform because our ERP will give errors if we try to push quantities with wrong units through.

[BenLoosli]

Where I have worked in the past, every part going into an assembly had to have a part number. That also meant that the engineers had o design every part, even a simple tube at x.xx length. Some of those parts that were only length differences, we put into a family table that everyone could add to, but were told not to change any existing values. If you can live with bulk items, that is another way, but that does not allow the same 'part' to be used at different lengths in different assemblies. I prefer bulk items for things that are hard to quantify how much was used in any given assembly, like paint or grease.

[KenFarley]

I've done a good bit of stuff with 80/20 and Rexroth aluminum extrusions and this is exactly how we handled things, too. For a particular project and specific extrusion profile, I would start with a basic part and then add all the instances based on length, possible added features to handle different joining techniques, etc. If you set up the model parameters you can have things like the part description include a length specification, etc.

The only wrinkle I have seen is I guess Windchill does not play well with family table stuff. We don't have Windchill but this is something I've heard before.

[BenLoosli]

Windchill has no problems with family tables as long as you keep them simple and remember that you cannot delete any instances once created. At my last job, I had over 13,000 parts in my family tables all in Windchill. Some tables had over 1000 instances in them. I limited them to common hardware items, bolts, screws, washers, nuts, etc. that were very easy to build into a family table. Things like a bolt head, which is defined by the bolt nominal size, were put into relations, not the family table. The family table would be items that changed, bolt size, length, thread pitch, thread class and finish.

[N-Pyn]

I am very hesitant about instructing our users to start using family tables. I don't trust that they would not make some mistakes and cause problems that are really difficult and slow to fix. I have had to fix some family table errors in Windchill previously and it is not fun.

It's a can of worms I don't want to open. It's just easier to say to the engineers to never use family tables than let them use them in some cases and hope that the usage stays inside those limits.

[Dale_Rosema]

P/N: ####-####

We currently have a base number that defines the part, the first for digits of the number, a dash, then four digits that define the length.

e.g.

5020-2756 = a 2.25" diameter tube with (2) predefined holes at an overall length of 27.56".

They are all in a family table.

[N-Pyn]

That solution has two aspects that I do not like at all:
Part numbers encoded with information that can change and family tables.

[KenFarley]

The only time I will encode information in a part number is if it is necessary to specify a part which must be purchased. For example, SMC electronic components are always specified by part numbers that are a long string of letters and numbers that identify the base part, plus the numerous options available for it. You need the number to be encoded to properly specify the part.

Similarly, Carr Lane drill bushings and other tooling hardware are defined by a base part number plus a number that specifies the inner diameter of the component. You have to have that last number encoded in the part number in order to fully specify the thing.

But, those are special cases. Hardware related. I don't like encoded part numbers for things I'm creating. No matter what kind of scheme you think up, something always breaks it. Plus, if you realize you need to make something shorter or longer, instead of a simple revision change to the part, you need to "replace" it with a new part with a new number that reflects the new length.

[Catalina]

Hi @N-Pyn,

I wanted to see if you got the help you needed.

If so, please mark the appropriate reply as the Accepted Solution or please feel free to detail in a reply what has helped you and mark it as the Accepted Solution. It will help other members who may have the same question.

Of course, if you have more to share on your issue, please pursue the conversation.

Thanks,