Questions on Deep Draw Vac Forming 1

[KENAT]

We are working on a product that includes some vacuum formed parts. They are fairly deep draw, the one I'm concerned with right now is about 12" or slightly more draw. We need to maintain reasonable thickness on the parts.

We had a vendor lined up, that did some good prototypes from this aspect, they used .187 start material and on the formed parts the thickest material was around .12 while the thinnest was around .09. So fairly consistent thickness, thinnest material was about 75% of the thickest.

However these parts were a bit too flimsy so we decided to look for .25 start material. We also had to change vendor due to problems with the first company on just about every other aspect of the project.

The new company supplied some first units yesterday. First off they ignored the drawing and made some of the units from .187" material. Then they rushed a sample to us made from .25" material.

All the samples showed severe thinning - in the order of the thinnest parts being only 35% the thickness of the thickest parts.

They are now being, shall we say, awkward about agreeing to improve on this.

Does this sound like something they should be able to improve on and get to a minimum thickness comparable to parts from our first vendor?

On the proto parts starting at .187 material thickness we were getting around .09-.11 in the thinner regions. So with .25" start Material were hoping to get around .11"-.14" formed thickness at the thinnest parts. The sample actually had around .05"-.06" at the thinnest parts.

Thanks,

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[btrueblood]

"internal politics"

Say no more. I've found liberal doses of Guiness to be effective treatment for that malady.

 

[KENAT]

Well, as much as I might like to drown some of our purchasing management and their plant manager I'm not sure it's an option;-). Plus seems like a waist of Guinness when a sewage pond would work well enough.

On our side the politics is that Engineering are paying, and view this as a development not just production contract with an element of risk and that as such either a margin should have been in the original quote or there should be scope for reasonable adjustment of the price to cover extra effort required. Our purchasing dept has treated this like a production contract and wanted fixed firm price against my 80-90% complete drawing and still has that mentality.

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[btrueblood]

As the doctor said to the patient who told him he wasn't taking his suppositories because they tasted terrible..."you're applying it to the wrong end of the problem."

We have a similar problem here - sent our newly developed parts to a new supplier against my better judgement, and they came back with a lovely abrasive deburr done to the expensive 8 rms lathe-turned finish (ok, my fault - I should have specified a circular lay on my finish callout, and not expected the flagnote "lathe turn this surface" to be sufficient...like you said, 80% complete drawings).

 

[KENAT]

On the 80-90% complete drawing, our original plan was they'd work with us to flesh most of it out before making parts but for one reason or another that hasn't really happened. They're only 80-90% complete because I don't know enough about Vacuum Forming & Polyurethane Foam molding to complete them.

Funny thing is though, we offered them more money to cover the extra engineering effort earlier this afternoon and they declined, so I may have been wrong thinking that our purchasing driving too hard a bargain was a major part of the problem.

Seems like we now have a plan to resolve the issue. Although, as it's very similar to the plan we had Thursday of last week, which didn't pan out, I do have some concerns.

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[patprimmer]

I strongly support the concept of about 90% complete drawing until an acceptable working part is made, then make the drawing match the part proven to work.

On jobs breaking new ground, even less complete drawings and on ho hum been there done that many times jobs, maybe 100% complete, but still subject to revision if something unexpected happens..

Regards
Pat
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[HDS]

Can they compensate in some other way like stiffening it up with the foam more than the previous vendor did?

 

[KENAT]

Stiffening with foam isn't an option - the foam needs to be soft enough to create a seal as well as have some other properties for acoustic insulation. Doubler of any kind would be tricky too - especially as the foam tooling is already made.

That said, on the phone yesterday they claim to have addressed the issue. I tried to go down to see myself yesterday afternoon but they really didn't want me to visit. So they shipped a sample overnight. Unfortunately I'm not there today but my colleague will review it.

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[btrueblood]

"but they really didn't want me to visit"

WARNING! WARNING! Danger Will Robinson! Man does that attitude raise red flags for me...

Tell your colleague to scratch at a few internal corners with a sharp pointy thing, see if they did some quick bondo and paint patches...

 

[KENAT]

btrue, we have the same feeling - what are they hiding? I explicitly said I didn't want the red carpet treatment and could be in & out in 10 minutes or so if necessary, but they still didn't want me to go. I could have given them approval yesterday afternoon, instead of them having to wait until about 1/2 an hour ago for my colleague to do it after getting the sample. When we need parts on 17th I'd have thought saving almost a day would be a good thing.

The sample is just the front Vac formed piece, not painted etc, so I doubt they'd have been able to do the kind of thing you said.

My colleague sent me an email with some info on it - I missed him when I called. It doesn't quite meet the min/max thickness we asked them for earlier this week but does meet it where it matters most and the other area is pretty close. Most importantly it 'feels stiffer' which is pretty much the important thing.

Now there's the issue that the trimming at one point is a bit dodgy and what this might imply!

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[btrueblood]

Nice way to start your weekend, eh?

I got a nicer start...an assembly tech had the whole shop up in arms against me about refusing to rework some new parts...then he went on vacation yesterday with scant notice. I walked thru the rework with the rest of the shop (including the foreman who was out sick yesterday) this AM, and they all pretty much apologized sheepishly for yesterday's kerfuffle. Parts were reworked in under an hour (they don't have work right now, and are basically sweeping floors and polishing tools waiting for some more orders to come in...). The ass'y tech is pretty much on everybody's skit list now.

 

[KENAT]

Well the part I was initially concerned with does indeed look good.

In a significant change of heart today they asked if one of us could rush down today to look at paint samples!

We're arranging a courier to bring it here instead, but still a bit of a change from 'don't come anywhere near us' that I got Thursday.

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[patprimmer]

Maybe their confidence level is indicated by their inclination or not to offer hospitality.

Regards
Pat
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[KENAT]

Maybe. They also send an improved sample of the other vac formed part they're making for us with the courier and it looks really good.

They did admit they have problems with another tool, but seem to think they can still give us some finished parts on schedule.

The turn around in the last week or so has been enough to give us whip-lash!

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