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Radii in plastic off-tool parts

Geneg

New member
Hi ProE people.
I wonder if anybody has a problem with getting slastic off-tool parts with sharp edges, while ProE part files have all the radii applied. Parts fail tests due to a breakage at sharp corners. Some of the radii can not be added later because of a parting line being already established without a R in consideration.

What do you do, how to deliver that important information to a tool maker (in <?:namespace prefix = st1 ns = "urn:schemas-microsoft-com:eek:ffice:smarttags" /><ST1:COUNTRY-REGIoN><ST1:pLACE>China</ST1:pLACE></ST1:COUNTRY-REGIoN>)?
Edited by: Geneg
 

burnsp

New member
Boy, that's really a wide open question but I think the answer is pretty basic. That feature should be clearly shown and properly dimensionedon whatever medium you used to transfer the design (drawing, part model,etc...). Additionally, it should have been discussed during a design/drawing review with manufacturing. Lastly it could be caught when inspecting the manufacturing prototypes, although with a mold this can be too late - maybe that's where you are.


Perhaps if you clarify your situation, others can also chime in with their .02.
 

Geneg

New member
Thanks for your reply.


We do deliver Pro/E part file and a drawing. Tool maker supresses all R for his tooling needs, and never brings them into tool. Thats creates aproblem. since we are in US and tool maker in China and probably do not speak English creates a disconnect.


I wonder what typical drawing notes will say regarding R on all sharp edges.
Edited by: Geneg
 

burnsp

New member
Sounds as if your problem is much larger than this one radii issue. If they can't speak/read english and your drawings have english notes - sounds like a losing proposition. It also sounds as if the problems need to be solved athigh management level - not between the design engineerand manufacturing engineer. If you're going to continue with this relationship, I would at least require FAI (first article inspeciton) for each different part before accepting or paying for any parts. This is SOP for most companies.
 

jeff4136

New member
Pardon me for asking, but: Is this "for real"?

It sounds almost like someone in Pakistan (or where ever) is just trying to make "China" look bad.
 

Geneg

New member
I am posting a problem that I have to deal with, being blamed for: no reason to make China look bad.
Edited by: Geneg
 

jrobi

New member
NOTE: ALL SHARP CORNERS ARE TO BE CONDITIONED


TO RX.XXMIN TO RX.XXMAX EXCEPT AS SPECIFICALLY NOTED. tHat is what i have done in the past with chinese molders. and, if there is a sharp corner to be maintened, provide a PLASTIC part drawing calling out the 'SHARP' corner, and also note on the tooling, 'THIS EDGE NO RADIUS'.
 

Huug

New member
When exchanging fully detailed and functional Pro/E parts, you got always to deal with the risk that the toolmaker modifies it. In this particular situation he deleted (suppressed?) the radii. He is right when he says (in chinese) that is easier for him, but you got to deal with the functionality of your part. And that is including radii.


Bad communication with toolmakers or other suppliers abroad is a common problem. When selecting a reliable, certifiedand english speaking partner, there's always the risk that they will source (some of) the moulds also, locally. I've seen mould drawings with logo's of complete unknown companies in the lower right corner. And I've got parts that were made of the preliminary files meant for quotation.



A strategy that one of our customers uses, is the "big-bang" approach. One meeting in China, one CD with the finalized parts. No preliminary parts, no quotation in advance, no revision drawings. Just the deal. Works fine. But you got to be sure the parts are "cavity ready", including all the parting lines, sprue locations, slides, drafts,rounds and so on.


Another method is to create neutral files, with just the dump geometry. So the toolmaker can't change anything. Or, you make a neutral file of that geometry that is functional, including the strictly needed radii, and ad all those other radii on that dump geometry, which he can suppress for his convenience.


Another approach can be to add those radii on your part that are convex. So the toolmaker can add the concave radii in the mould, eventuallyby hand. In the cavity they are convex, so they need only to remove steel from the mould. This is generally done after the first shots.


Huug
 

BMD

New member
I have design plastic injection molds for years and I suspect I know what your problem is.


When tool makers get your part files that do not contain the draft needed to create the tool they have to add it. If they are using another software what they have from you is dumb data. They need to fill in all the radii, add the needed draft, and add the radii back. It sounds like they don't put the radii back befor splitting the tool and generating cutter paths. If they are using ProE it sounds like they get in front of the radii and add the draft. Then they either leave the rounds supressed or tey don't bother to fix them when they fail, which they will do.


Try sending them models that are fully drafted and rounded so the file is moldable.


When I deal with dumb data part files the first thing I do is export a wire frame igs file and import it back in, putting it on a layer named wire_yymmdd. This gives me curvesfor reference to rebuild the part after drafting the part for moldability.


Steve
 

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