Semiproduct with machining allowance

[mbonka]

Hello,

l really need some inspiration from our clever PTC community. l will describe my problem as simply as possible. See attached files, that l used to describe my problem.

1) Target:

Parameter ROZMER shows a semiproduct size that should be order from a shop and should be delivered to engineering shop.

A) ROZMER must include a machining allowance.

B) ROZMER must change if the part has been changed.

2) Present situation:

See attached files please. Note: Some relations are on feater level in 1st model tree feater. It works perfect until l need add some machining allowance.

If a part needs a machining allowance, than l have to delete/deactive a ROZMER relation and change ROZMER manually. It´s a big source of failures, because future part modification are not propagate to ROZMER. In result l will order a smaller/bigger semiproduct. ---> this is bad system solution.

3) Description:

Parameter ROZMER (eng translate = semiproduct) includes information about material size.

How l use parameter ROZMER? --- ROZMER is shown in BOM tables ---> table exported to TXT file ---> TXT file imported to excel ---> excel table exported as PDF ---> PDF send to shop as an order list.

4) Ordinary parts from our company:

- solid part - needs an X,Y,Z (weidht, height, thick) machining allowance

- sheetmetal parts - needs an X,Y (thick is everytime same) machining allowance

- beams - needs a lenght machining allowance

Most of semiproduct comes form CNC laser/water cut. From this reason l need a DXF/DWG file. This file HAS TO include a shape with machining allowance.

5) My ideas:

A) Put a machining allowance into relation ---> PROBLEM: Parameter ROZMER is correct, but DXF file is bad.

6) My problem questions:

- How to include machining allowance? This allowance should be reflected in drawing space (DXF/DWG files for cnc cut)

7) Generall questions:

- What is your machining allowance system / strategy?

- How do you export DXF/WWG files with machining allowance?

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[TomU]

I think what you're looking for are the bounding box dimensions of the model (plus some additional added for rough stock). Unfortunately these are not easy to retrieve. You will need to either do something with Model Check or create a custom program (J-Link, VB, etc.).

The only workaround I can think of is to create a solid surface copy of the model and use planes some arbitrary distance away to measure to this surface from each of the 6 directions. Simple math would produce the equivalent bounding box dimensions. Of course the problem with this approach is that you need to make sure any new features are always created prior to this surface copy.

[mbonka]

Sounds too comlicated.

l can´t imagine how present thise to my colleagues...

[mbonka]

Forgot about example parts.

See attachment please.

[dschenken]

Start with ROZMER sized initial feature and only allow cuts to remove material in the models.

For sheet metal, start with flat piece.

[TomU]

Agree! Treat the CAD model like the actual piece of material. No model "sculpting". (Adding and removing material over and over again.) Never add material after the first feature.

[TomD.inPDX]

Known as "raw material". If you must specify the raw material you will have to create a part that meets that specification so it can be ordered. It may or may not have a drawing. It will in all likelihood have a specification that controls the raw material.

The 1st level assembly (CAD assembly) will be the fabrication detail, which is always removing material. You can even do operations like welding by adding more materials (assembled parts) and also doing material removal operations at this level and subsequent levels. It is all about how much control you need as to how many levels you are creating on your bill of material.

Some raw materials will be ordered in standard length. These are considered "bulk materials" and planning needs to go into these as well... for instance, if you need an I-beam 4 feet long and your raw material comes in 10 foot lengths, you can can only get 2 pieces out of a 10 foot beam. What are you going to do with the 2 footer? Do you even need to acocunt for the 2 footer. Hopefully purchasing can get a 12 or 16 foot beam and your design can live with 3 foot 11 inches to maximize yields.

P.S. I don't do RAR files on principle.