What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
(OP)
I am a product engineer that makes drawings for parts that need to be vapor polished. In the past I have received parts that were spec’ed to be vapor polished, yet showed up not polished. The parts were buffed slightly so it was a bit hard to tell if they have been polished or not, this was the first time I had ordered the part, so it was hard to tell if it was polished or not. (Very small part, about the diameter of a BIC pen and a thickness of 0.053"). I used the parts thinking they were polished. Later to learn from the vendor they were not. This problem got sorted out, but in the future inspection will not be done by me, it will be done by a non-technical QA employee. How do I make sure they know what a polished part looks like? Give them a polished and a non-polished piece and allow them to do a visual comparison? My company is very small (I am 1 of 2 engineers) so we don't have a lot of cash for inspection equipment.
Thanks for any insight.
Thanks for any insight.





RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
-Dustin
Professional Engineer
Pretty good with SolidWorks
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
I hate working with vendors that make me have to think like this, but it is simply the truth. Maybe it is becuase we are small fish, so we need to use small fish vendors that are not as stellar as other companies that we simply can't afford.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
Include in your PO and contract paperwork an item which allows you to pick a testing lab of your choice, X number of random selected parts, you pick them, for verification and certification, at a fixed price to the supplier. Non-conformance has a significant penalty cost to the supplier. And, you have already arranged this inspection and testing, and its cost with the local lab of your choice.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
how critical to the performance of the part is the polishing ? how critical is the function of the part ? (if it fails, can it kill people?)
if you can't trust your vendors, get different vendors! if you have to work with them ('cause their your boss' buddies) get them to pay for 3rd party inspection. (how will the 3rd party inspection comfirm the polishing?)
Quando Omni Flunkus Moritati
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
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RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
how do you know if a surface is 128, 64, or 256 (surface roughness)?
Quando Omni Flunkus Moritati
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
My origional question was about how to spec out vapor polish and that the person inspecting parts is not an engineer. That question still stands. First are there people here that spec out polish of some kind and need to inspect their parts? If so how is this inspected?
I know I can use outside vendors to verify things, I will tell you right now that is 100% out of the question for how things are run here. Simply put, never ever going to happen. Cost and time is far to great. No parts have any potential to hurt anyone, ever. We always strive to look for new competent vendors, but what about if you have been using a vendor for 10 years with no issue and all of a sudden they make a mistake? You walk away? If that is how you work you will spend all you time looking for vendors, and not designing products. As for the company that messed up, no, they did not pay anything. That is not part of my job though, I do not deal with what happens after the failure, I just try and guarantee that they don't happen as best I can (practically for free). It is a whole differnt mind set when working for a fast moving small company, there is little time to do inspections and things like that. For example, when I make a drawing for a stainless steel probe that must be 316 to avoid rusting how do I verify that it is 316? I use a COC (Certificate of Compliance). That is all I can rely on, I do not have time of $ to send the parts out for verification.
Does no one else have these issues? All your companies have the capital to get evey part analyzed before use to ensure that it is truly the material you speced out? Same goes for plastics, how to confirm that White ABS is not actually White PVC. They look extreamly similar.
I guess that is my main point, how do others verify or feel confident about things that can not be checked???
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
i understand narrow margins and no time to check.
the person doing the inspection doesn't need to be an engineer, these days they only need to be able to read ! (CoC, tick; more along)
a lot of things look alike (different steel tempers and alloys, plastics, etc) ... there are no doubt tests for comfirming this type of plastic or that, etc; but you don't have time for that. you trust the CoC and that's the end of it.
remember everyone, and i mean Everyone, was caught out some years back with "bogus bolts" ... H11 bolts that didn't meet spec.
Quando Omni Flunkus Moritati
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
Mike Halloran
Pembroke Pines, FL, USA
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
I have had vendors polish things that were not supposed to be polished too, simply because they, and I quote "polish and anneal all acrylic parts". Just strange. Of course we can stop using them someday, but that is not my question, my question is how do you stop them during inspection the first time, not leave them after the damage is done.
Maybe there is no way, without spending $ and time. Just wanted to gauge the rest of you guys to see if there was perhaps something I was not thinking of.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
How to inspect that something has been made correctly: You specify vapor polish for a reason, right? There is something quantifiable that works correctly when the part is vapor polished and doesn't work correctly when the part is not vapor polished. So you perform an inspection to measure that quantifiable thing. You need to identify what that quantifiable thing is, then perhaps someone can suggest you to inspect for it.
Inspector is not an engineer: Then you write an inspection procedure at a level of detail appropriate for their level of education and train them on how to perform the procedure.
How to perform an inspection for free: Don't do an inspection.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
This is not the right question to ask.
Anything can be checked. Some things more easily than others.
What you want to ask is "How can I feel confident that things are made correctly so that I don't have to check each and every one?"
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
"how do others verify or feel confident about things that can not be checked???"
You don't, particularly if your supplier is not cooperative. It also doesn't matter how long you've used them. If they make a mistake, that's one thing. If they actually lie about it, you can elevate the problem through their management, but if there is no resolution, run away. There are enough good suppliers that can and will do a job as quoted, per drawing, for the same or less cost than one that ships unuseable items.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
This is one of the reasons you specify the results, not the process.
Specify how shiny and transparent your part must be. You do not care how they do it. Now, the thing is checkable.
--
JHG
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
So let me start at the top and give a little more detail since everything everyone has stated is quite obviouse to everyone else in here, as well as me.
Here we go:
The part is made from clear cast acrylic, is about 0.240" is diameter x 0.053" thick. It has some small features to it like ultrasonic energy directors, flash traps and a thru hole of 0.080". Looks a lot like the smallest pieces LEGO makes. During my prototype phase of my project I speced out Vapor Polish in my "Finish" box of my drawing. This is what I always do. I got the parts from a very trusted supplier that does good work. The got me the parts and I could not tell if they were polished or not seeing as how they were so small and I figured maybe it is hard to polish such a small part well. I used them and they worked. Later on after buying the parts again, this time my purchasing department used a vendor with a shorter lead time, the part parts showed up looking VERY clear. This was the first time I thought to myself. "Maybe the first lot I got was not polished". The polishing ended up making my parts weld slightly worse. The parts that were NOT made to the drawing actually worked better! So of course I changed my drawing, but that is not why I started this thread. What I wanted to know is that for something that is clearly subjective, like clarity in this instance, how do people spec things out? Of course there are ways to spec anything in the world, but I can't make this thing cost more than $2, and I only need to buy a couple hundred at a time. The part is small, and my company is not going to send the parts out for testing, we are also not going to buy expensive equipment to test for clarity. Those ideas are literally on another planet in terms of something a company like this would ever spend its money on. Also it not so critical that someone could ever get hurt or anything like that. It is litterally like making a LEGO that needs to be clear, (or actually not clear, due to the welding), not to any specific spec, just clear. We can't test this and I can't expect the QA person to know what the correct level of clear is. Can I? I have thought of setting up a part catalouge that shows how polished parts should look. This would give a gold standard, and if a part comes in not looking like the standard the lot can be failed, or engineering can be called to confirm the failure?
Anyways, I have gone on long enough. I have so much more to ask but feel like this example is maybe a bit too convoluted to get thru here. General consesuse seems to be test or find a new vendor, or to add a clarity spec. Something I can't even measure. Maybe the gold standard and training of the QA inspector is the way to go... or only way to go given the constraints I have...
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
i think it's a problem with out-sourcing ... it's hard to have the discussions about how a part is going to be used, what's better for the ultimate product ? with out-sourcing, the vendor gets the drwg and makes it; sure sometimes the vendor works with the prime to develop the part (but that often breaks down into squabbles over SoW and cost).
Quando Omni Flunkus Moritati
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
i think in your case the easiest way is to get a prototype part, a little trial and error, then say "build like that one". maybe let your QA keep the reference sample. if the parts do come polished, you could always scuff them on next stage of ass'y.
Quando Omni Flunkus Moritati
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
I suggest having samples sent to the vendor as well as keeping in your own inspection, drawing note something like.
FINISH: PART SHALL BE VAPOR POLISHED ON BOTH SIDES TO MATCH SAMPLE COUPON XXXXX. COMPARISON SHALL BE MADE AT 2X MAGNIFICATION IN A WELL LIT AREA.
As to your in house inspection I'd prefer to leave that off the drawing and record it either in your quality plan or your routing or some such - nail down any other points you can such as sampling rate.
I work at a place that is struggling with inspection and relatively low volumes etc. too and sometimes the practical measures that can easily be implemented are pretty limited. That's potentially OK, just don't kid yourself that they're anything more than getting a warm fuzzy feeling.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
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RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
- After talking over with some other departments and getting other opinions here, someone suggested a photo of the part on the drawing so that QA knows what something looks like. An enginner that works with me brought up metal platting and how QA never knows what "clear zinc chromate platting" looks like over not platted steel. The plating is just a general anticorrosion plating we have applied to out sheet metal parts to keep them from rusting over time. Nothing critical, sort of like plating you would have on your IKEA bed frame, you need something, but don't want to pay tons of money for checking, it just isn't that critical. The photo may be the best "cheap" idea at being able to show QA what a plated part looks like. Only do this for parts that have special not easily checkable features. Apprt from that, there is the "gold standard" sample idea, I would like to stay away from this simply due to the amount of parts we would need to catalouge.
Anyways, I think I have a fairly good idea as to what others may be doing and what my options are. Also learned that trying to describe a part and the way my company works is quite hard to describe over the internet. haha. I will make sure to start off all my future posts with "OK so can't afford just about anyting..." and go from there.
Thanks for the help eveyone.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
I think KENAT's suggestion of keeping masters on hand is good, provided these are properly stored and handled. Ive seen 10 or 20 year old "masters" on somebodies window sill that have yellowed and warped.
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RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
Visual comparison to a known good part is already pretty marginal in its usefulness for quality control, comparison to a photo is worse.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
With that said, I agree that "masters" are a good idea. We have thousands of parts that we machine, blow mold, injection mold, rubber transfer mold, sheet metal stamp, cicuit boards, and buy as stock items. Saying that we will have a place that can house one "master" of all these doesn't sound like a completely reasonable solution.
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
One, the QC item is altered and unusable parts become accepted
Two, production is short one item, but they know where a good one is...
Three, an 'extra' item is found in production, and discarded, because it wasn't needed
Four, the inspection item is moved to production and an incoming piece is substituted.
A photo is OK subject to a bunch of assumptions. If it was that easy everyone would do it.
Perhaps a drawing note refering to a controlled QC video that is used to teach inspectors is possible. The tough part is determining what the limits are at which you want to reject parts.
***
For appearance control the usual methods are to either spend a lot of money on inspection equipment or to qualify the process, and sometimes both. For example a weld callout goes on the drawing. The welder is typically required to create a weld of the same type, which is tested, for approval before creating deliverable welds. The inspector gives a visual on the welds to see that they appear to be the same as the qualified welds. Even then, welds may require dye-penetrant or x-ray inspection. Paint is another one - samples are done for gloss and adhesion and the process adhered to.
Here's a strong article on why depending on visual inspection controls can be costly and why understanding process is critical to success: http://edn.com/design/analog/4427151/The-last-half...
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
So take a look at molding in one piece what is now an assembly.
Mike Halloran
Pembroke Pines, FL, USA
RE: What to put on a drawing that guarantees that your part is vapor polished? How to inspect?
2. Inspect using one of these. Link